vector antenna analyzer fa-v a5 - box73.de€¦ · vector antenna analyzer fa-v a5 ver e 1.3...

Assembly and Operating Manual

Kit for an easy to usevector antenna analyzerfor use in the frequency range10 kHz to 600 MHz.

Vector Antenna AnalyzerFA-VA5

Ver E 1.3 2019. 08. 06

BX-245 • 1© Box 73 Amateurfunkservice GmbH 2019

Radio amateurs who build their own antennas appreciate the value of a vector antenna analyzer. This device ischaracterized by high accuracy, small dimensions and easy operation. It allows one-port measurements in the fre-quency range from 10 kHz to 600 MHz and has a USB port for connection to computers.

Vector Antenna Analyzer FA-VA5SUPPORT DEPARTMENT OF GERMAN HAM RADIO MAGAZINE “FUNKAMATEUR”

Experiments with antennas make up a sub-stantial part of the hobby for many radioamateurs. The measurement of standing wave ratio(SWR) and the determination of theimpedance values are inseparable. The SWR can be estimated when transmit-ting using a SWR meter, but more exten-sive and accurate data is obtained using anantenna analyzer. However, such instruments are often ex-pensive whilst cheaper devices often lackaccuracy. The FA-VA5 closes this gap. Itis the successor to the successful FA-VA4which was also developed by MichaelKnitter, DG5MK [1]. The VA5 is a full-featured, vector-measur-ing device with a frequency range of 10kHz to 600 MHz, (Table 1) offering com-pact dimensions and a USB port for con-nection to a computer.

Vectorial measurement means that, unlikea scalar instrument, not only the SWR ismeasured and displayed, but also the valueof the impedance, including the signedimaginary part. The so-called SOL (Short,Open and Load) compensation, originatesfrom professional instruments, and is usedfor the calibration of the device and pro-vides precise measurements in differentconfigurations.The FA-VA5's graphic display shows thecomplex impedance, standing wave ratio,complex reflection coefficient, capaci-tance and inductance. An audible SWR indication using thebuilt-in piezo buzzer is also available. Theanalyser kit consists of an SMD-pre-as-sembled printed circuit board, a graphicdisplay including backlight, and a USBmodule in a specially designed enclosure.The microcontroller on the board is al-

ready programmed. The USB connectionallows not only the interaction of the FA-VA5 with Vector Network Analyzer soft-ware installed on the computer (VNWAApplication – see the corresponding chap-ter in this manual) but also permitsfirmware updates by the VA5 user. TheVA5 Menu structure is easily understoodby newcomers provided you spend a littletime reading relevant instructions in thismanual. The VA5 kit includes SOL cali-bration elements, which are usable up toabout 100 MHz. A high-quality calibrationkit, covering a frequency range up to 600MHz, can be purchased at [1].

2 • BX-245 © Box 73 Amateurfunkservice GmbH 2019

Technical data

Table 1: Technical dataFrequency range 0.01 MHz … 600 MHz, (resolution: 1 Hz)Measuring range limits SWR ≤ 100, Z ≤ 1000 Ω*Measurement result full impedance value (resistance and reactance), including signAccuracy ≤ 2 % (0.01MHz ≤ f ≤ 200 MHz, Z < 1000 Ω)Dynamic range Mode Precise: 80 dB to 200 MHz, 50 dB 200 MHz … 600 MHzof Return Loss Mode Standard: 75 dB to 200 MHz, 45 dB 200 MHz … 500 MHz Fast mode: 70 dB to 200 MHz, 40 dB 200 MHz … 500 MHzFrequency stability 0.5 ppm (–30 °C … +85 °C)Signal processing 24-bit ADC, 16-bit DSP, 32-bit calculationPower supply 2 ¥ 1.5V AA batteryMeasuring input 50 Ω, BNCOutput signal Squarewave f = 1 MHz, RL = 50 Ω: P1 = 5.6 dBm (1st harmonic, fundamental) P3 = –4.0 dBm (3rd harmonic) P5 = –8.3 dBm (5th harmonic) f = 200 MHz, RL = 50 Ω: P1 = 4.5 dBm (1st harmonic, fundamental) P3 = –7.2 dBm (3rd harmonic) P5 = –15.3 dBm (5th harmonic)Current consumption 38 mA** (65 mA) at 1 MHz, 47 mA** (85 mA) at 200 MHz, Load resistance 50 Ω, lighting switched off, single frequency measurement ZCurrent real time clock 0.9 μADimensions 127 mm ¥ 86 mm ¥ 23 mm (L ¥W ¥ H)Mass 280 g incl. AA batteries* Measurements beyond that, but possible with less accuracy

** Mean, peak in parentheses

ImportantThis construction manual was createdwith great care. All hints and advice contained therein are important for a successful construction! The same applies to the order of the assembly steps.

Any revision of the FA-VA5 Assemblyand User manual will be published as a pdffile on www.box73.de. Please check thiswebsite regularly.

You'll also find videos on assembling andoperating the VA5 Antenna Analyzer oncethese are published.


The following tools are required for as-sembly:– temperature-controlled soldering iron

60 … 80 W with pencil soldering tip, – solder 0.5 ..1.0 mm with flux core– 100 W soldering iron with chisel-shaped

soldering tip, – PCB side cutter pliers– flat-nose pliers, – 3mm slot screwdriver,

– Phillips screwdriver, – two 1.5V AA batteries (Mignon) for

power supply.

Before fitting the board, the contents ofthe kit should be checked off against theparts list in the appendix.

n Assembly of the board The few remaining components to be sol-dered are fitted only on the SMD Com-ponent (top) side of the motherboard.The position of the individual parts isshown on the assembly plan (Fig. 2) Switch and USB Interface board First, the slide switch S1 is soldered to thetopside of the board. It should rest flushon the board with no space underneath, itsactuating knob must be horizontal with re-spect to the board surface (Fig. 3). Theeasiest way to achieve this is if only oneof the solder pins of the switch is solderedfirst. After that, the switch can still be eas-ily aligned while heating the solder joint.When the correct mounting position isfound, all pins and the two housing tagsare soldered. The USB Interface Board is to be soldereddirectly to the top side of the main boardwith the supplied mica washer inserted forisolation purposes. The washer must lieflat and be placed exactly between the cor-responding soldering surfaces (Fig. 4). The front edge of the USB socket thenprojects slightly beyond the main board toterminate flush with the housing shell. Tinone of the relevant solder pads of the mainboard first, then positioned the USB boardincluding mica washer and fix the USB as-

Fig. 1: View of assembled FA-VA5 – Powerswitched off

Building instructions


sembly with some solder. To see if every-thing fits properly, screw the motherboardwith four M3 screws in the housing lowershell and then fit on the upper shell. TheUSB socket must now sit exactly behindthe rectangular cut-out on the left side ofthe housing. If necessary, the accuracy offit can now be corrected relatively easily.If everything is correct then continue andsolder all 16 solder pads of the USBBoard to the main board.

Fig. 3: Slide switch soldered in the correctposition. 6-pin header is obsolet

Fig. 4: USB interface board correctly posi-tioned

Fig. 2: Assembly plan of the FA-VA5 with components to be fitted

1

2021

40 USB Module

Battery1.5 V

AA

Battery1.5 V

AAS2

S3

SG1

S4

X1DIS1

S1G1

G2


DisplayA graphic LCD display with integral LEDbacklight is used to display the measureddata. Both components are already delivered as-sembled as a unit and are only to be sol-dered in certain places. Caution: Makesure the display is flush with the LEDbacklight so that there is no gap, then pro-ceed to solder all six connections of thetwo three-pin display contacts on the backof the backlight (Fig. 5). Also solder thetwo outer connections of the 20-pin con-tact strip (Fig. 6). It is recommended to use a suitable baseunder the display during soldering in orderto fix it flush on the lighting unit.Caution: The protective film on the glasssurface of the display must first be re-moved before assembling the housing. If you forget this, you will see a blackline on the display that suggests theglass is damaged.

Fig. 5: Display with backlight; all six connections must be soldered on top of the backlightPCB

Fig. 6: View of the 20-pin contact strip of the display after assembly. Only the two outer pinsare soldered on top of the backlight PCB. Remove the protective film from the display bypulling the red tab.


Socket stripsThe three socket strips for contacting theLC display are fitted next. The pre-assem-bled display can be used conveniently as agauge for their orientation.

Caution: The lower edge of the plasticbody of the socket must have a uniformdistance of exactly 7 mm to the board, toensure that the display eventually sits atthe correct height above the main board. To achieve this, cut the cardboard strip(supplied in the kit) into four parts andplace it during soldering as shown inFig. 7. Before soldering the female con-nectors, put these strips on the pins of thedisplay. To do this, place it upside down

on the work surface and carefully slide thethree socket strips onto the display pins.Make sure the socket strips are flush withthe display board as the 20-pin strip isprone to bend slightly. Place the display together with the socketstrips on the board. Next the four card-board strips are inserted (Fig. 8) then turnover whole assembly so you can solder thefemale connectors on the underside of theboard.

The female connectors must be exactlyvertical after soldering. Push-button switch, piezo buzzer,battery holders and BNC socket The three push-buttons, the piezo buzzerand the battery holders are fitted and sol-dered next. Caution: All these components must bemounted so they sit tight on the mainboard. Remove the protective foil of the

Fig. 7: Four cardboard strips are used forsetting the distance between female con-nectors and the PCB.

Fig. 8: Main PCB view before soldering the female connectors of the LC display; The card-board strips must be pulled out after soldering, also the display is removed (unplugged)again before fitting the remaining components. 6-pin header for programming is obsolet


piezo buzzer and locate the positive termi-nal. Fit this component so the positive pinpoints in the direction of the battery holder. Next fit the battery holders, observing cor-rect polarity (Fig. 2). Caution: the springcontact is the negative pole. The solder ter-minals of the battery holders are made ofspring steel. Use suitably robust side-cut-ter-pliers to trim the excess length of theswitches, battery holder and buzzer termi-nals, making sure that these terminals donot touch the housing later.Finally, fit the BNC socket and solder onthe board. Again, this part must sit flush andbe aligned horizontally and at right anglesto the edge of the board. The two groundpins are to be soldered on the underside ofthe board with a 100 W soldering iron toensure the solder flows well in order toavoid cold solder joints. At the same time,the soldering time should be kept relativelyshort so that the insulation inside the socketis not damaged (Fig. 10). The thin terminalsshould also be cut after soldering in orderto avoid short circuits with the housing. Functional test and final AssemblyBefore installing the board into the hous-ing, a short functional test is required. Firstfit the three plastic caps on the push-but-tons and fit the previously assembled dis-play in the corresponding sockets. Ensure

the slide switch is set to the off position(Fig. 10), then insert two 1.5 V batterieswith the correct polarity and switch on thedevice with the slide switch. The start-up welcome message shouldnow appear briefly on the display, the FA-VA5 then switches to measuring mode. If the display remains blank, then all sol-der joints made in the previous steps must

be carefully checked and reworked if nec-essary. Once the functional test is complet-ed, move the slide switch back to the offposition and remove the batteries frombattery holders. The fully assembled boardis shown in Fig. 9. Installation in the enclosure First, the four rubber feet are inserted intothe lower shell of the enclosure. It is helpfulto pull with the flat-nose pliers on the thinrubber nipple on the inside and at the sametime to turn the rubber foot slightly. Thencut the protruding rubber nipples to 2 mmwith the side cutter (Fig. 11) so that theydo not touch the board later. The board is

Fig. 9: FA-VA5 Main Printed Circuit Board: fully assembled (6-pin header is obsolet)

Fig. 10: Slide switch in position Off


now inserted by sliding the BNC jack intothe housing lower shell and the four M3screws are screwed in at the corners of theboard and gently tightened. The BNCsocket must then be screwed together withthe toothed washer and nut and gentlytightened.To avoid mechanical stresses on the mainboard, the four fixing screws of the boardshould be loosened and tightened again,then do the same with the nut of the BNCsocket. Now insert the batteries observing correctpolarity. Next the housing cover is fittedand fastened with four M3 countersunkscrews. Finally, attach the Instrument type label tothe bottom of the housing! The FA-VA5 isnow ready for operation and can alreadybe used in uncalibrated mode. General notes on operation The FA-VA5 antenna analyzer can be usedas a measuring device immediately after

assembly. It then operates in uncalibratedmode and the displayed results are subjectto a higher error than is the case after acorrect calibration. The uncalibrated modecan always be selected later via the SetupMenu if, for example, there are doubtsabout the validity of the stored calibrationdata. n CautionsPlease note the FA-VA5 is a sensitive mea-suring device. No RF energy shouldreach the test socket to avoid destroyingthe components at the input! This couldhappen when transmitting with the anten-na connected in close proximity of theVA5. Likewise, static charges must bekept away from the test socket. Isolatedantenna structures must therefore be dis-charged by grounding them first. Rechargeable batteries should not beused in the FA-VA5 because there is noelectronic protection against over-dis-charge and there is no battery charging fa-cility in the instrument. Deep dischargemakes rechargeable batteries useless andcan even destroy them. Leaking batteriescan also cause damage.The FA-VA5 is designed to make opti-mum use of 1.5V alkaline cells. If the bat-tery voltage is less than 2.5 V at switch-on, the display will show a Battery LOW

warning. In order to achieve the longestpossible battery life, it is advisable to usethe display backlight only if it is other-wise impossible to read the display. Indaylight or outdoors the backlight is usu-ally not needed. A dimmed brightness set-ting will also help to save power. The number of measurements or displaycycles should be selected to produce a re-peat rate that is sufficient for the measure-ment in question. These parameters canbe changed in the Setup menu and have asignificant influence on the power con-sumption and thus on the life of the bat-teries. It is advisable that BNC plugs should beturned slightly back and forth after thebayonet catch engages to improve contactengagement. Otherwise, under certain cir-cumstances, “inexplicable” measuring er-rors may occur.

Fig. 11: Cut rubber feet after insertion intothe housing


Although the FA-VA5 has a relativelylarge range of functions, the operation isquite intuitive. Therefore, the followingguide has the character of a referencebook. However, the general operating in-structions in the previous section shouldalways be observed. The instrument can-not be destroyed by pressing buttons thewrong way, and at worst this will provideunexpected or erroneous measurement re-sults. Therefore, it is recommended thatless experienced users start-off by measur-ing some components with known values,then gradually explore the operation of theantenna analyzer by trying out differentmeasurement and display modes. If ambi-guity arises please consult this manual.For precise measurements, calibration(SOL compensation) is important. It istherefore detailed in this independent sec-tion of the functional description. The an-tenna analyzer works according to the fol-lowing principle: An internal oscillatorgenerates a signal with a specified fre-quency, which is routed via the BNC out-put socket of the device to a test object (forexample an antenna). Due to the electricalproperties of the test object, the test signalis changed in amplitude and phase. This

change is measured to determine theimpedance relative to known componentvalues either directly or through the reflec-tion coefficient (after calibration has beenperformed). All other values(e.g. SWR)are mathematically calculated from themeasured impedance by the built-in mi-crocontroller. n Controls and ConnectorsThe only measurement port on the analy-zer is the BNC connector. For operation, an on / off power switchand three press buttons are available. TheAnalyzer will always be in the previousmeasurement mode after power isswitched on as all parameters are savedwhen power is switched off. The three but-tons have different functions depending onthe selected measuring or operating mode. In general, a function is called up or a se-lection is made with the left push button.The centre and right buttons are used toreduce or increase numerical values or tomove through menu lists. A rapid change of numerical values (e.g.frequency values for multi-frequencymeasurements) can alternatively be ob-tained by pressing and holding the middle

or right buttons. At any time, the availablefunctions are displayed on the displayabove each of the buttons. A 2-second long press on the left buttoncalls up the menu mode in measuringmode. After that, the middle and right but-tons allow you to select a menu itemwhich can then be selected or activatedwith the left button. Other button functionsare explained in the following sections.This description refers to the firmwareversion 1.09.

Directions for use


Power Switch-onAfter switching-on power on the FA-VA5,a start-up message appears on the display,which includes the firmware version andthe current battery voltage. The factory default setting of the menu language isEnglish. The language can be changed toGerman by making following buttonpresses: Long 2-second press on Left Button: →Operating Mode → Centre button: press 7¥ → Setup→ 1 ¥ → Language→ 2 ¥ → German → left button →

.n Basic Calibration (SOL Compensation)

Each additional connector and cable af-fects the accuracy of the impedance mea-surement on the device under test (DUT).However, these unwanted errors can befully calibrated out by the Short OpenLoadmethod (abbreviated to SOL method). Three known calibration elements aremeasured instead of the test object. TheShort element applies a short circuit overthe BNC socket, the Open simulates anopen cable end and the Load element pro-vides a resistance equal to the systemimpedance (in our case 50 Ω). During cal-ibration, the software of the FA-VA5“measures” the reflections of a short cir-

cuit (0 Ohm = start of measurement scale)and of an open circuit (Infinity Ohms =end of measurement scale) as well as thereference value Z = 50 Ω at the input (=midpoint of scale). These values are thethree defined points of reflection. Due tothe physical properties (tolerances) of realcomponents, no absolutely exact valueswill prevail at the input hence the devia-tion must be detected and later eliminatedfrom the measurement result. The processof acquisition is called “Calibration”.Without calibration, the measurement re-sult would be subject to a relatively fixed,recurring and frequency-dependent error.During the master calibration, the actualinput impedance is automatically mea-sured at intervals of 100 kHz or 1 MHz forall three reflection defined cases, and thecalculated correction data is stored perma-nently in memory. The microcontrollersoftware retrieves and applies appropriatecorrection factors later whenever calculat-ing the measurement results. If the mea-suring frequency is between two calibra-tion points, then interpolation of thecorrection is performed. Three Calibration elements with accept-able accuracy up to about 100 MHz can beeasily made by yourself using three BNCcoaxial cable plugs (50 Ω). The Short,Open and Load elements supplied with

the FA-VA5 will provide acceptable accu-racy up to about 100 MHz. You can easilymake your own using three BNC coaxialcable plugs (50 Ω). To make the Short cal-ibration element, the inner conductor andplug housing are short-circuited, whilst inthe Open calibration element the pin ofthe inner remains unconnected (see attach-ment) and the Load element has a low-impedance 50 Ω SMD metal layer resistorsoldered between the inner conductor andthe housing of the plug.High Quality BNC calibration optionAn optional high-quality BNC calibrationset, which can be used up to 600 MHz isavailable from [1]. The load element ofthis calibration set is individually mea-sured for highest accuracy and the mea-sured data is provided in a printed instruc-tion leaflet. This data is then entered in theFA-VA5 Setup menu (see section Calibra-tion Set Data).The data supplied for the load elementconsists of: picosecond delay, ohms resis-tance, femtofarad parasitic capacitance,and nanohenry parasitic inductance. In addition the delay values for Short andOpen elements should be entered: this isalways – 41.66 ps for the open elementand always –113.52 ps for the Short ele-ment.


When using the optional High QualityCalibration set, all these values must beentered in Setup → Cal/Port Model Mas-ter and also in Cal/Port Model Actual. Once this data has been entered the mastercalibration has to be carried out. Note: When using the VNWA software,these individual values can be loaded viaa parameter file. The individual file can beaccessed via the link specified on the in-struction leaflet supplied with the Calibra-tion kit (CKF file). Loading and using theCKF file is described in the Help for the

VNWA software. After completion of thecalibration, the correction values are auto-matically stored in the analyzer so that thecorrect impedance is determined on sub-sequent measurements of the test object. n Basic CalibrationThree different calibration methods areavailable for each measurement mode ofthe analyzer:No CalibrationThis is the factory default condition, it canbe accessed through the menu by disablingthe calibration. This option can be enabledor disabled and is accessed via Operatingmode → Setup → SOL. Selecting... “Off”sets the “No Calibration mode”Current calibrationThis can be performed for single-frequen-cy mode (Fig. 13) as well as for multi-fre-quency (Fig. 14) and 5-band measurementmode. The process affects only the actual singlefrequency or the frequency range selectedand therefore completes very quickly. Cur-rent calibration makes it possible to quick-ly compensate for temporary changes inthe measurement setup or the parametersdue to temperature or other influences. Caution! Current calibration values are

lost when changing the frequency andwhen switching off the analyzer.

Fig. 12: The kit contains a set of calibrationelements for use in the frequency range up toabout 100 MHz, consisting of a 50 Ω Termina-tion from Telegärtner (centre) and two BNCcoaxial cable connector for making the Shortand Open reference elements (see text).

A set of Quality BNC calibration elements us-able up to at least 600 MHz including mea-surement data report is available under orderno. BX-245-SOL.

Fig. 13: Menu item for SOL compensation forthe actual frequency

Fig. 14: SOL compensation for the actual Fre-quencies for a multi-frequency measurement


Master calibrationIt is possible to permanently store SOLcalibration values for the entire measuringrange. The analyzer steps through the en-tire frequency range with the Short cali-bration element connected and stores themeasured values. The same process is re-peated for the Open and the Load ele-ments. It is recommended to perform theMaster Calibration once directly on eitherthe BNC connector, or at the end of a per-manently connected cable or a permanent-ly connected test setup as part of the ana-lyzer commissioning process. OnceMaster calibration has been performedmeasurements can be made at any timewithout new calibration. This Master calibration function can beaccessed via Operating mode → Setup →SOL All frequencies (Fig. 15). Master cal-ibration will be selected automaticallywhenever the current calibration becomesinvalid. Caution: Prior to starting Master Calibra-tion, do make sure that Cal/Port ModelMaster data for Load, Short and Open (ifavailable) is entered first in Setup, other-wise the Master Calibration will be invalid.Note: The Master Calibration processtakes about 20–25 minutes, but can becancelled if desired. In this case, however,inconsistent reference values may arise, so

this calibration should be repeated at theearliest opportunity. Which calibration method is actually beingused can be seen on the display. Thus, themaster calibration is used in Fig. 16 for theSWR measurement, recognizable by theabbreviation M to the right of the bargraph. After single-frequency calibration,there would be aC here (for Current SOL),whilst an uncalibrated measurement is in-dicated as a – (dash character) at this point. n FA-VA5 menu system: Use the left button to enter the menumode (long 2-second button press). Thenthere are choices according to Table 2(Fig. 17 … 19). Within the menu, use the

and buttons to move to the de-sired point and then select it with thebutton. A new submenu is indicated by asmall arrow > pointing to the right. Thecurrent selection is inverse and slightly in-dented. The system contains three types of menuitems: Measurement Modes, Functionsand Setup. The desired Measurement – Operatingmode can always be selected immediately.

Fig. 15: Starting point of the master calibration

Fig. 16: Master calibration used in this mea-surement


All functions, such as setting of the clocktime or the SOL compensation etc will goback to the menu from which the functionwas called by pressing Return. All set-tings, e.g. Backlight Mode or Display Up-date Cycle, can be selected directly in thecorresponding Setup menu.

Fig. 17: Operating mode, first part

Fig. 18: Operating mode, second part

Fig. 19: Operating modes, third part

Table 2: Selection options in FA-VA5 operating modeMenu item MeaningReturn Return to the previous measurement modeSingle frequency modes SWR, Impedance or Reflection coefficient measurement at current frequency, SWR measurement with sound signal, current calibration Multifrequency modes SWR, Impedance or Reflection coefficient measurement within a frequency range (multi-frequency measurement) in the single or cyclic run, 5-band SWR measurement, current calibrationFrequency generator RF generator modeLCR Meter Display of the measured value of Inductance, Capacitance, Resistance and Quality of connected components at a selected measuring frequencyClock Displays the call sign, the time and the dateUSB manual USB modeData From Memory Display and Deletion of Saved Measurements Results (Display Data) Recall and Deletion of stored Measurement Presets (Presets)Setup Enables the Setup menu (see Table 3)


n Measurement Options with theFA-VA5

The Operating mode allows you to selectthe most commonly used measurementand display settings in practice. Single Frequency MeasurementsThe Single Frequency Mode menu itemis the first of the operating mode selectionsand measures either SWR, impedance Z orreflection coefficient S. When selecting SWR measurement (Fig.20) the current measuring frequency(freq), the standing wave ratio (SWR), theresistance of the impedance (formula Z),the reactance of the impedance (+ j /- j)and the SWR are also displayed. In addition, the reference impedance forthe SWR calculation (here 50 Ω), the typeof calibration used (see section Basic Cal-ibration) and the impedance model (S orP, i.e. serial or parallel) are shown on theright edge of the display. The memory indicator S in the upper rightcorner of the display indicates that allchanged values have been stored in theEEPROM of the Analyzer. When measurement mode SWR1 FrequBuzzer is selected, the piezo buzzer pro-vides a beeping noise during the measure-ment as an acoustic aid, e.g. for antennatuning. As the SWR decreases, the faster

the beeps will sound, making it easy tohear when the lowest SWR is measured. The actual measuring frequency can beset using the three buttons. Use the leftbutton ( ) to select the point of thefrequency to be changed, indicated bythe underscore or position indicator.With the middle or right button,the value of the selected digit is reducedor increased. You may need to press andhold the button slightly longerthan usual to change the value. In the Impedance measurement (Fig.21), the bar graph is omitted comparedto the SWR measurement. Instead, theequivalent capacitance or inductance ofthe imaginary part for a serial or parallelreplacement element is displayed. When measuring the Reflection coeffi-cients (Fig. 22), the display shows thereal and imaginary part (S), the magni-tude and phase angle (phi), the reflectionloss (dB) and Matching Loss (dB). Within the Single Frequency Modesmenu item, Current calibration at the setfrequency is also possible at any time.After acquiring the reference values, theAnalyzer returns to the current measur-ing mode by selecting Return, if neces-sary.

Fig. 20: Single frequency measurement SWR

Fig. 22: Single frequency measurement of theReflection coefficient

Fig. 21: Single frequency measurement ofImpedance


Multifrequency measurementsThe Multi Frequency Modes menu itemallows the SWR to be measured on fivefrequency bands. There is also a Sweepmode to measure SWR, impedance Z andreflection coefficient S (multi-frequencymeasurement). The Sweep mode can beselected as a single or cyclic run. SWR measurement on fivefrequenciesIn SWR 5 Band mode (Fig. 23), five SWRvalues are displayed in the bar graph forfive different frequencies. The actual five frequencies can be enteredor changed in the Setup mode via menuitem 5 Band Frequencies. Fig. 25 showsan example of setting the frequency ƒ1. Itis analogous to setting the measuring fre-quency of the Analyzer in Single Frequen-cy Mode. Then press the button re-peatedly until the abbreviation isshown to the right of the frequency value.After pressing the or button, youcan move to ƒ2, ƒ3 etc. (see also sectionSetup). There is no further operating op-tion in this measuring mode. With thismeasurement mode, you can check andcapture the effects of changes made tomultiband antennas in one simple mea-surement. In addition to the use of mastercalibration, current calibration via the

menu item SOL 5 Band is also possiblefor this mode (Fig. 24). Prior to perform-ing Current calibration, however, the fiverequired measuring frequencies must havebeen selected first. Sweep modeThe Sweep mode (multi-frequency mea-surement) has three different sub-modes,which are selected via the left button andmarked with an icon in the upper left cor-ner of the display. The three sub-modes areindicated with characters <, > and MMode 1: this mode is indicated by charac-ter < and provides changing of the centrefrequency. The SWR is displayed abovethe frequency. In addition, a small rectan-gle on the SWR curve indicates the posi-tion of the marker (see sub-mode M). Thecentre vertical line corresponds to the in-dicated centre frequency (7300 kHz inFig. 26). The full frequency range extendsto the left and right according to the se-lected frequency range (here ± 2000 kHz).The middle and right buttons can be usedto reduce or increase the centre frequencyby 100 kHz. At the same time, a new mea-suring cycle over the specified frequencyrange is initiated each time the button ispressed.

Fig. 24: Additional current calibration optionfor the mode SWR 5 frequencies

Fig. 23: Simultaneous SWR measurementson 5 programmable frequencies

Fig. 25: Selection of frequency f1

© Box 73 Amateurfunkservice GmbH 2019

Mode 2: this mode is indicated by char-acter > and provides an overview ofmarker values and changing of the settingof the frequency span. Again the SWR isdisplayed above the centre frequency. Inaddition, the small rectangle on the SWRcurve indicates the position of the marker(see sub-mode M). Using the middle andright buttons, the frequency (sweep)range can be increased or decreased by afactor of 2 (within the available frequen-cy or measuring range see also Start Fre-quency Sweep in the section Setup). Atthe same time, a new measuring cycleover the selected frequency range is start-ed each time the button is pressed. Themeasured value at the marker frequencyis displayed on the bottom right of thedisplay (Fig. 26). Mode 3: this mode is indicated by charac-ter M (marker character) and provides aview and adjustment of marker valuesover the previous frequency span. The se-lected frequency of the marker and the as-sociated SWR is displayed (withoutboundary value limitation). The marker it-self is again shown as a small rectangle onthe SWR curve. Using the middle and theright button, the marker can now bemoved along the previous measurementcurve in a total of 100 steps (Fig. 27, seealso Auto SWR in the section Setup).

In contrast to modes < and >, pressing abutton does not trigger a new measuringcycle, but merely displays the changedmarker position including the correspond-ing measured value. The measured values obtained beforeswitching to mode M were “frozen” andcan now be “skimmed” using the marker.A new measured value acquisition takesplace again when switching to sub-modes1 or 2 indicated by < or >. The combina-tion of these three sub-modes thus makesit possible in a simple manner to “ap-proach” target frequency ranges duringmeasurements, to narrow them down andto query specific values at relevant points. For internal SOL compensation, the instru-

ment uses either the calibration valuesfrom the master calibration or or uses thecurrent calibration values generated via themenu item SOL Sweep. Prior to perform-ing this calibration, the centre frequencyand frequency span must be selected forthe current calibration to run correctly.

Fig. 26: Multi-frequency measurement of theSWR; the arrow on the top left, pointing tothe right shows that an increase or reductionof the frequency span range can be madeusing the plus or minus buttons.

Fig. 27: Multi-frequency measurement of theSWR; The current marker values are dis-played.

Fig. 28: Example of a multi-frequency mea-surement the impedance; using plus / minusbuttons the centre frequency of the spanarea changes, as indicated by the arrow onthe top left pointing towards the left side.

16 • BX-245


Multi-frequency measurements of theimpedance and the reflection coefficientare in principle similar as when measuringSWR. The same applies to the operationof the Analyzer (Fig. 28 … 30). In additionto the single pass, which is only triggered

again when a measuring parameter ischanged on the device, it is also possibleto select the cyclic measuring run (Con-tinuous Sweep run). This is automaticallyrestarted by the Analyzer again and again.Changes in the measured values are there-fore relatively quickly visible. The disad-vantage, however, is a higher power con-sumption of the device.

Fig. 29: Example of the multi-frequency mea-surement the impedance; the real and imag-inary parts are displayed next to the markerfrequency.

Fig. 30: Example of the multi-frequency mea-surement the reflection coefficient, the re-sult is a small Smith chart; the real and Imag-inary part and other calculated valuesare displayed below the marker frequency.

n Additional Operating modes

Frequency Generator

The FA-VA5 operates as a RF generatorwith a square wave output signal at theBNC socket after selecting the menu itemFrequency generator. Its peak outputvoltage is about 1 Vpp to 50 Ω. The actualsignal frequency is displayed (Fig. 31).The frequency setting is made using thethree buttons (choice of decimal point tobe changed with , decrease valuewith and increase value with ). LCR Meter The LCR Meter menu item is used to dis-play the results when measuring coils, capacitors and resistors at a chosen mea-suring frequency. This can be used to de-termine the suitability of passive compo-nents for HF circuits (Fig. 33).Simultaneous quality measurements re-quires careful calibration of the instrumentto obtain good accuracy.Clock (with Call Sign)When the menu item Clock is selected, theset call sign, date and time are shown inthe display (Fig. 32).

USB mode (manual switching)The menu item USB is also used for man-ual switching to USB mode (Fig. 34), seealso section Setup. Saved Views, Datasets and PresetsPreviously saved Screen views and/or Da-taset information can be selected here. Allmeasurement modes allow you to save ascreen snapshot of the current display view.To do this, briefly press the left and rightbuttons at the same time. In the subsequentscreen snapshot menu, one of ten memorylocations (#0…#9) can be set using themiddle and right-hand buttonsand selected using the left button.Previously saved views of the selectedmemory location will be overwritten. Thesame is possible on a total of 16 memorylocations for Dataset records. The lattercan be displayed in the view mode ortransferred to the PC via USB for docu-mentation purposes (see relevant section). Saving takes a few seconds because all thepixel data of the display contents are trans-ferred to the EEPROM.The same is possi-ble on a total of 16 memory locations forthe data of actual measurement results.The latter can be stored as a Dataset andrecalled later via USB and transferred tothe PC for documentation purposes (seecorresponding section).


Fig. 33: In the mode LCR meter, the FA-VA5displays the measured values in a large andclear representation.

Fig. 32: Callsign and time and date displayed

Fig. 31: Screen display when operating theFA-VA5 as an RF generator


Measurement values, saved as a Dataset,cannot be displayed on the FA-VA5 andError is shown instead.Up to five measurements modes (Presets)can also be saved in the same way. Forexample, it is possible to restore an impor-tant or frequently recurring measurementsetting quickly from a previously storedPreset after switching-on power to the de-vice without incurring a long delay or se-arch (Fig. 35).

If you need this for the current measure-ment mode, just save the mode using SaveData and Preset and later call this backup with Load Data and Preset.To see these views, select the menu itemData from Memory → Screen in opera-ting mode (Fig. 35). The correspondingdisplay memory can be selected with the

and buttons (Fig. 37). Unusedmemory locations are displayed empty.The left button allows you to returnto the previous measuring mode. To visu-ally distinguish from current measurementresults, a saved screen view is displayedwithin a frame (Fig. 38).To distinguish from current measurementresults, a saved Screen is shown within aframe (border) (Fig. 38). A short press onthe left button allows you to return to theprevious mode.

Fig. 34: Display after switching to the USBmode

Fig. 35: Access to saved Screens and Pre-sets

Fig. 36: Menu items for deleting storedScreens, Datasets and Measurement Presets.

Fig. 37: A saved screen display with times-tamp which can be re-called.

Fig. 38: A saved screenshot is displayed with-in a surrounding frame.


n Setup mode The following Setup options are located ina separate menu as they are less frequentlyused in practice. They are accessible viaOperating mode → Setup (Fig. 39). Themiddle and right buttons are used to selectthe corresponding option, the left buttonactivates the selection. Language

This option allows the selection of the lan-guage used in menus and measured valuedisplays: English or German are possible(Fig. 40). Frequency values for 5-bandmeasurementAfter selecting this menu item (Operatingmode → Setup → 5 Band frequencies), entering or changing of the first of the fivefrequencies is prompted for (ƒ1–ƒ5). To dothis, use the left-hand button to setthe position indicator to the position of thefrequency value digit to be changed, andif necessary, correct this with the plus orminus button. When jumping from the lastdigit left to the first digit right (1 Hz), theabbreviation for Enter appears.Pressing the or button will nowsave the set value for ƒ1 and jump to thefrequency entry for ƒ2. This is repeated until frequency f5 (page 15, Fig. 25). Af-

ter confirmation of the last frequency, theanalyzer returns to the previous measuringmode. ClockThe time and date are set here. The FA-VA5 has an internal real-time clock thatcontinues to run after the unit is turned offand is powered by the unit's battery. Powerconsumption is very low. The date andtime are primarily used to ensure a correcttimestamp for stored records. A suitably dimensioned backup capacitorbridges the short time of battery replace-ment, so normally the clock does not haveto be reset.

Fig. 40: Setup option of the menu language

Fig. 39: Setup mode, first section


Table 3: Available Options in Setup mode of the FA-VA5Menu item MeaningReturn Return to operating modeLanguage Selection of the menu language5 Band Frequencies Definition of the frequency values for 5-band measurementClock Setup of time and dateSweep DSP Mode DSP Setup Fast / Standard / Precise for selecting measuring accuracy and measuring timeCal/Port Model Master Input of data from the SOL elements for master calibrationCal/Port Model Actual Entry of SOL element data used for current calibrationSOL All Frequencies SOL compensation over the entire frequency range (Master calibration)Callsign Personalization option by entering the call signBacklight Mode Setup of the display backlight optionsDisplay Update cycle Defines the repetition rate of the measurementsUSB Auto Mode Automatically switches the FA-VA5 to USB modeDelta Frequency Calibration of internal TCXO reference frequencySOL Option to switch calibration on / offZ0 Base Change of reference impedance for SWR calculationsImpedance Model Switching between Serial and Parallel modelZ Range Sweep Determines the impedance range for multi-frequency measurementsStart Sweep Mode Frequency range increment / decrement options for multi-frequency measurementsAuto SWV Enabling/Disabling of the minimum value Auto SWR marker in multi-frequency SWR measurements. Options are on/offFirmware Start of the firmware updateReset Reset to factory settings


DSP SetupIn the multi-function Sweep DSP Modemenu, DSP settings can be made for mul-ti-frequency measurements (Fig. 42). Theoptions are Fast, Standard and Precise.

Note: More accurate measurement re-quires longer execution times. Calibration Set DataAccuracy of the displayed measurementdata, especially at higher frequencies, de-pends entirely on the SOL calibration setused and how calibration is carried out.The menu items Cal/Port Model Masterand Cal/Port Model Actual allow you toenter appropriate parameters for the mas-ter and the current calibration. In practicethis data is provided by the manufacturerof the calibration kit and is entered onlyonce. In addition, it is possible to move themeasurement plane level by port extensionby specifying a runtime in picoseconds. SOL All FrequenciesThis item has already been covered in thesection Basic Calibration (SOL Compen-sation).

CallsignIf you want to personalize your FA-VA5,you can use this menu item, e.g. to saveyour call sign (maximum 9 characters). Display BacklightThe available options are Off, Dim, On,Auto, Backlight Auto Time and Back-light%. (Fig. 44 and 45). When Auto is se-lected, the backlight is switched off aftersome time, but is switched on again whena button is pressed by the user. It is recom-mended to set the display backlight to Offor to Auto mode, as power consumptionof the graphic display with backlight Onis relatively high. The switch-on time ofthe backlight in Auto mode can be set onseconds via menu item Backlight Autotime. In addition, the FA-VA5 also offersthe possibility of working with reducedbacklight which will lower power con-sumption. The mode will then be Dim in-stead of On. The associated menu itemBacklight % is used to set the brightnesssetting.

Fig. 41: Setup mode, second section

Fig. 43: Setup mode, third section

Fig. 42: DSP Setup options


Display Update CycleFor single frequency measurements, theoptions are Slow, Medium and Fast. Theselection has no influence on the measure-ment accuracy, but has large impact on thepower consumption requirements of theAnalyzer. Except during measurements,the oscillator and other components areswitched off and the microcontroller isclocked at a lower frequency. A longer dis-play duration therefore meets a lowerpower requirement (Fig. 46). USB Auto ModeAfter connecting to a Personal Computer(PC) via USB cable, the FA-VA5 will beautomatically powered from the PC.Whether it also automatically switches toUSB mode or has to be switched manuallyis selected in this menu. (see also descrip-tion of USB function in section OperatingMode)

Fig. 46: The display repetition rate can be setto Slow, Medium or Fast.

Fig. 44: Backlight options, upper part of themenu

Fig. 45: Backlight options, lower Part of themenu


Delta FrequencyThis allows for optional Frequency Cor-rection of the internal oscillator. All inter-nal frequency values are derived from ahigh quality 26MHz temperature-con-trolled crystal oscillator (TCXO), whichinherently has very little frequency devia-tion or drift. Any remaining residual devi-ation can be compensated by software. Forthis purpose, first set a frequency of26.000000 MHz in the frequency genera-tor mode. Then connect a calibrated fre-quency counter to the BNC output connec-tor of the Analyzer and determine thedifference between the measured and thedisplayed frequency. After selecting theCorrection Frequency menu item, firstpress the left button. Then the valuefor df is set to the determined differenceusing the middle and right buttons (mea-sured frequency minus 26.000000MHz).The button is again used to select thedecimal place. Repeatedly pressing thisbutton leads to the display of the abbrevi-ation ENT (Fig. 48). When the orbutton is pressed, the FA-VA5 accepts thevalue set as the frequency correction.Thereafter, the frequency of the Analyzeroutput signal should be exactly equal to theset frequency. It should be noted, however,that this frequency correction is usually notrequired for antenna measurements.

SOL = Calibration On / OffIf required, the stored calibration can beswitched on / off via menu item SOL. Thiscan be useful if there are doubts about thevalidity of the stored data, for example.ZO Base = Reference impedanceSWR measurement values refer to a systemimpedance Z0. This reference impedancecan be selected via the menu item Z0 Base(Fig. 49) which is displayed at the rightedge of the display during measurement(see section Measurements with the FA-VA5). Available settings are: ZO = 25 Ohm, ZO= 50 Ohm (default setting) and ZO = 75Ohm)Impedance ModelThe FA-VA5 can display the impedance ineither of the corresponding measurementmodes as either a Serial (default setting)or Parallel model. At the same time, thecalculation of the equivalent capacitance /inductance of the imaginary part for a se-rial or parallel equivalent element is per-formed. The selection is made in the menuitem Impedance Model.

Fig. 47: Setup mode, fourth section

Fig. 48: Input option for the correction of thefrequency offset

Fig. 49: Selection options for the Referenceimpedance basis


Z Range SweepThe maximum display range for Z multi-frequency measurements can be selectedhere. Either a maximum value of 200 Ω,400 Ω or 800 Ω can be selected. (Fig. 52).Caution: please note that a maximum val-ue of 800 Ω already deviates relatively farfrom the system impedance of the device.Measurements of impedances on this scaletherefore have a lower accuracy. Frequency range for multi-frequencymeasurementsIn case of a multi-frequency measurement(see section Sweeping Mode, the frequen-cy range is increased or decreased bypressing a button according to a fixed pat-tern. This selected scheme can be set viathe present menu item (Fig. 53). The selection Start 100 kHz means that thefrequency range can be changed in kilo-Hertz increments in the following steps: 2 – 5 – 10 – 20 – 50 – 100 – 200 – 500 –1000 kHz etc. With Start 2 kHz one canselect steps 2 – 4 – 8 – 16 – 32 – 64 – 128– 256 – 512 – 1024 kHz etc. SWR minimum for multi-frequencymeasurementsWith SWR multi-frequency measurements,the marker can be automatically set to dis-play minimum SWR and this value can be

transferred to the single frequency mea-surement. To do this, in the Auto SWRmenu item, select the item On. During thesubsequent SWR multi-frequency mea-surement, the marker point automaticallyjumps to the frequency of minimum SWRafter the first pass. If you now switch to theM mode (see section Sweep Mode), this fre-quency is saved and will be automaticallyused after switching to single measure-ment. This allows a quick overview andsubsequent detailed measurement.FirmwareSelecting the menu item Firmware startsthe firmware update of the FA-VA5. Thisis done as follows: – Connect the FA-VA5 to the PC via USB,

read and note the assigned virtual COMport in the Windows Device Manager

Fig. 50: Setup mode, fifth section

Fig. 52: Maximum values of the impedancefor Multi-frequency measurements

Fig. 51: Setting mode, sixth section

Fig. 53: Selection of the Sweep increment/decrement options of the frequency span formulti-frequency measurements


– Unpack the packed directory containingthe update at any point on the PC

– Firmware update starts when selectingthis option and the FA-VA5 displaystarts flashing

– In the unzipped directory on the PC se-lect and then start the batch file namedfirmware_update_VA5_Vxxx.bat (whereVxxx is the actual Firmware version)with a double click. The batch file thenprompts to enter the assigned COM portand the display stops flashing and thecurrent data transmission is displayed.

After successfully completing a firmwareupdate, the FA-VA5 must be re-initializedin most cases, as the new firmware willuse different memory addresses. This isdone by resetting the FA-VA5 to the facto-ry settings (see next section). Then, as aprecaution, the master calibration shouldalso be repeated. For each update, there is

a readme file that lists the software changesand provides installation instructions.These instructions must be followed eachtime a firmware update is done.ResetWhen this option is selected and con-firmed, all parameters are reset to the fac-tory settings and the master calibrationand all stored display views are deleted(Fig. 54).Forced resetIn the unlikely case that the Analyzer sud-denly stops responding to operator inputs,and this state persists despite switching offand on again, a Forced reset can be appliedwithout a menu at any time: To do this,switch off the Analyzer. Then press andhold all three buttons at the same time.Now, when the power is switched on, allparameters are reset to factory settings andthe device should work as usual. If neces-sary, correct the language, backlight andfrequency settings. Note: a Forced Resetdoes not erase existing master calibrationvalues or saved display views. Any exist-ing values of the master calibration mustbe enabled again. To do this, under Oper-ating mode → Setup → SOL option “On”must be selected. Caution: this step mustbe performed even if the SOL menu al-

ready displays the status as “On”, as mas-ter calibration is only enabled once it man-ually set to “On” following a Forced Re-set.

Fig. 54: This menu allows reset to the factorysettings.


n Tips on measurement practiceMeasuring complex impedances posesmany options. The measurement exampleslisted below can therefore only hint atthese. Further explanations of the physicaland mathematical correlations can befound in specialist literature. It is assumedthat a master calibration was performedwith or without the cable attached (de-pending on the measurement setup). If thetest structure is changed later, e.g. by re-placing the cable, calibration must be car-ried out again. When making antennameasurements note that the FA-VA5 is an“active” analyzer which generates andoutputs RF to the antenna under test.Therefore, the measurement timeshould be kept as short as possible toavoid the possibility of causing inter-ference to other users. Tests on fre-quencies outside the amateur radiobands should be avoided.

Multi-Frequency Measurement ofImpedance and SWR of an AntennaThe antenna is connected to the Analyzerdirectly at the base or via a cable previ-ously included in the calibration by SOLcompensation. Using the multi-frequencymeasurement, an overview of the SWR orimpedance curve can be generated. Thecentre frequency and the frequency span

are set as required for the spectrum to bemeasured. The marker mode can be usedto “approach” an SWR minimum. In antennas with high Q-factors (e.g. mag-netic antennas), more attention is neededto obtain accurate measurements. Themaxima and minima are so narrow thatthese may not be displayed depending onthe selected frequency span. The answeris to carefully select the centre frequencyand to reduce the frequency span (sweep)range accordingly to ensure meaningfulresults are obtained. Measuring impedance and SWR ofan antenna at one frequencyThe antenna is connected directly to thebase or via a cable to the analyzer. Youwill need to decide if the whole system ofantenna and cable or only the antennashould be measured. If the latter applies,the cable must be disconnected at the baseof the antenna (usually designed as a plugconnection). The analyzer should be set to a single fre-quency measurement of SWR orimpedance. Then the target frequency isentered. The cable is now included in themeasurement: remove the feeder cablefrom the base of the antenna. SOL Cali-bration should now be done for this fre-quency via the menu item SOL One fre-

quency for the current frequency by con-necting the calibration elements to the endof the antenna cable as previously de-scribed in Calibration.Next, reconnect the cable to the antennabase and the actual SWR or impedance ofthe antenna can now be measured and dis-played. The way of tuning the antenna foroptimal SWR and / or resonance dependson the antenna type. For example, amonoband dipole with balun may be tunedby shortening or lengthening the dipolelegs. If there is an impedance with nega-tive reactance (capacitive), the antenna istoo short. On the other hand, if the Anten-na is too long for the measured frequency,a positive reactance (inductive) will bedisplayed. The aim is to achieve a resis-tance of 50 Ω and with an imaginary partof the impedance of zero (resonance case). Measuring Capacitance andInductanceFor measurement of components at fre-quencies up to 30 MHz, simple adaptersmade of 2.54 mm pin headers and socketsand matching SOL reference elements hasproven to be successful. For the measure-ment, mode LCR Meter is used. The targetfrequency must be set and then calibrationperformed using menu item SOL One fre-quency for the existing test setup. The


measurement object is connected directlyto the selected measurement setup and thecapacitance or inductance at the target fre-quency can now be read on the display. Using the Antenna Analyzer as a dip-meterIf a signal-generating source (in our casethe analyzer) is loosely coupled to a paral-lel resonant circuit, different levels of en-ergy absorption by the circuit occur out-side of resonance compared to theresonant frequency of the circuit. This alsocauses a change in the displayed SWR val-ue. Loose coupling to the resonant circuitunder test is usually carried out inductive-ly. It is sufficient to position the analyzer'sBNC socket with a one turn coil (one wire)near the resonant circuit. For a toroidalcore, a 1 turn link must be added throughthe toroidal core. At very low frequencies(ƒ< 1 MHz) a test with several turns maybe needed.Multi-frequency SWR measurementThe expected resonance frequency shouldbe entered as the centre frequency and alarge frequency span selected. Then thefrequency span of the measurement shouldbe reduced in several steps in order to beable to read the resonant frequency withthe best possible accuracy. It should show

a clear SWR minimum. It is not alwayseasy to find this minimum because it canbe very narrow in high-quality resonantcircuits. The function Auto SWR offersgood support here.Cable resonances and resonatorsThe analyzer makes it easy to detect reso-nance points from coaxial and other RFcables. For this, the unknown cable is con-nected to the analyzer. The other end canbe left open or shorted. When the cable end is open resonances oc-cur at wavelengths of 1/4, 3/4, etc. of theelectrical length of the cable (High Zimpedance)When the cable end is shorted, the reso-nances occur at wavelengths of 1/2, 1, 3/2,etc. of the electrical length of the cable.Resonance means that the reactance of theimpedance is zero. Therefore, a Z-multi-frequency measure-ment is used here. For the HF range, itmakes sense to start with a centre frequen-cy of 15 MHz and a maximum frequencyspan. The resonances appear at the pointswhere the reactance crosses the x-axis (ze-ro magnitude). The exact frequency caneasily be approached in marker mode. Conversely, this method can also be usedto produce cable resonators for a targetfrequency. For this purpose, the physical

length can be roughly estimated using themethod of the next section. A slightlylonger cable should then be shortenedgradually until the target resonant frequen-cy is reached. Wavelength and physicallength of a resonant cable are linked by thevelocity factor. This is the ratio of the free-space speed of light with the speed of thewave on the cable, because the wave prop-agates on the cable slower than in a vacu-um. For RG58 coaxial cable, for example,the velocity reduction factor is 0.66. Thepropagation speed is therefore only198 000 km/s instead of around 300 000km/s. Length, propagation velocity andresonant frequency are linked by the for-mula

vl = ––– · N.ƒ

N is a factor 1/4, 1/2, 3/4, etc., depending onwhich resonance point is considered andwhether the cable is open or shorted at theother end. If the resonant frequency of acable is determined on the basis of the pre-vious section, the physical length can becalculated by means of the above equationand using the velocity factor typical for thecable. Conversely, the same formula canbe used to determine the velocity factorfor a known physical cable length.


The VNWA Windows software developedby Thomas Baier, DG8SAQ, for the SDR-Kits VNWA vector network analyzer canalso be used to display the measured val-ues and control the FA-VA5 antenna ana-lyzer. The VNWA application can bedownloaded (free for VA5 users) fromRef [2].Data measured with the FA-VA5 locallycan be saved on the computer and can beused for documentation or reference pur-poses. In addition, the VNWA softwarecan also completely take over the controlof the FA-VA5. Together the FA-VA5 andthe VNWA application form a fully-fledged measuring station up to 600 MHz. Controlling the FA-VA5 hardware fromthe VNWA Application: In the followingparagraphs the connection of the FA-VA5to the PC, as well as the installation andthe most important steps for using the soft-ware are described. A comprehensive pdfhelp document in English and Germanlanguages for the VNWA Application isavailable for download from [2]. Setting and usage options beyond the fol-lowing brief introduction are described indetail in the helpfile, albeit these refer tothe VNWA3 hardware. However, the sec-

tions of interest in the FA-VA5 (all one-port measurements) are easily identified.n PC connection of the FA-VA5If you have not already done so, youshould first connect the FA-VA 5 to the PCvia a USB cable to install the driver. Theanalyzer does not need to be switched onfor this because it is powered up via theUSB connection. The operating systemdoes not automatically find the correctdriver for Silicon Labs on all tested ver-sions of Windows 7 or later. It is thereforerecommended to install the driver manu-

ally from the link shown on page 38 Ref.[3]. Successful installation of the SiliconLabs driver can be verified via the Win-dows Device Manager. Connections COM

& LPT should show that the Silicon Labsdriver is installed. In the example ofFig. 55, it occupies virtual COM portCOM5, as shown. The number of the usedCOM port should be remembered as it willbe needed for the set-up of the VNWAsoftware. If there is a quotation mark shownin Windows Device Manager, the driver hasto be downloaded as explained above. (A recent update of WIN10 seems to installa wrong driver, downloading the driverfrom [4] and installing it fixes this issue).n Installing the VNWA softwareThe file downloaded from [2] is namedVNWA-installer.exe. This is an executablefile that already contains all the softwarelibraries required to connect the FA-VA5.After the EXE file has been downloaded, itmust be executed. The subsequent installa-tion is, as usual with Windows software,menu-driven and largely self-explanatory.All the suggested options can be confirmedwith the response Next. A License key orcertificate is not required to operate theFA-VA5. This prompt can be bypassed byselecting Next or Exit. After installation,the VNWA software must be started. A warning message will be displayed that

Fig. 55: Section from the display of the Win-dows Device Manager showing COM portused by by FA-VA5 in USB mode.

VNWA Windows PC Software


does not concern the FA-VA5 and cantherefore be confirmed with ok. The sameapplies to the following warning.The VNWA entry screen is initially quitesimple and uncluttered (Fig. 56). The soft-ware at the bottom left of the window willreport that no VNWA hardware has been

detected. If the existing grid is not clearlyvisible (depending on the standard win-dow colour of the Windows version), thebackground colour can be changed via themenu item Settings → Diagrams → Dis-play → Grid Options and thus adapted toyour own taste.

n Connecting the FA-VA5 to VNWA:

The FA-VA5 must be able to communicatewith the PC before you can use VNWAsoftware. To do this, put the analyzer inUSB mode. If this has not already beenchanged by the user in the FA-VA5 menu(go to Setup→ USB Auto Mode), the ana-lyzer will automatically switch to USBmode when the USB cable is inserted.Otherwise, the USB mode can be manual-ly selected at any time via the Operatingmenu. Once this has been done, in the VN-WA Application under Options → SelectInstruments → Add to / remove, from thedisplayed list select → DG5MK AntennaAnalyzer. Now the FA-VA5 has been added to thelist of selectable devices. The actual selec-tion is then made using Options → SelectInstrument → DG5MK Antenna Analyz-er. Next VNWA still needs to know whichCOM port was detected by the WindowsDevice Manager. This is done in the VN-WA Application under Options → Setup.A new window opens and the correctCOM port is selected from the list in boxPort. A successful connection to the FA-VA5 is acknowledged on the top right withthe word connected in green and a statusline in blue indicating the firmware ver-sion of the analyzer (Fig. 57). This com-Fig. 56: VNWA Startup screen after installation of VNWA Software


pletes the connection of the FA-VA5 to theVNWA software. Incidentally, the VNWA application “re-members” all settings after closing theprogram. For this reason, the next time theFA-VA5 is put into operation, it is neces-sary to plug the VA5 in the same USB porton the Computer before using the VNWAprogram next time. A second importantsetting is the sweep selection range in theinteraction of FA-VA5 and VNWA whichis found under Settings→ Sweep (Fig. 58).In addition to some basic settings for mul-ti-frequency measurements with VNWAas controlling software, the second tab ofthis window allows the import of locallystored data sets of the FA-VA5 as de-scribed below. n Dataset records ImportAfter clicking on the second tab in Fig. 58,a window appears as shown in Fig. 59.Here, analogous to the local menu of theFA-VA5, the 16 available Dataset recordsare listed with their time stamp. By select-ing a dataset record with a left-click andthen right-clicking the corresponding lineof the context menu, the correspondingdataset will now be saved in a file or toWindows clipboard. The latter is also pos-sible by double-clicking with the leftmouse button. The file path and name of

Fig. 58: Setup selection window for the basicsweep (multi-frequency measurements) anddata import

Fig. 57: Example of the FA-VA5 Setup screenin VNWA application

Fig. 59: Selection window for data import; inthis example only one record was saved onthe FA-VA5

Fig. 60: Section of the selection window forthe data import; a successful transmissionof the Data to the clipboard is confirmed inthe Footer of the window.


the file can be freely selected. Their formatcorresponds to the widely used Touch-stone format, which is also readable withan editor (like Windows notepad). The following example copies the data tothe clipboard. After a double click, the VN-

WA reads the data into the Windows clip-board and confirms the process (Fig. 60).Then the relevant window can be closed.The final step is to transfer the data fromthe clipboard to the VNWA memory. Thememory relevant for the FA-VA5 should

always be S11 (see Appendix 1 at the endof the manual). The transmission takesplace via a right-click of a displayed S11output channel (Fig. 61). In the main win-dow bottom left is (for example) a channelS11 Smith chart shown in red. By right-clicking directly on S11 and Import s1p →from Clipboard, the data is loaded into theS11 memory. The graphic display is pro-cessed and is displayed in the main win-dow of the program, a popup info-windowconfirms the read-in process (Fig. 62). Forthe familiar SWR display, the followingquick fix solution is available, which wasalready anticipated in Fig. 62: double-clickon the similarly visible S21 in blue, in thesubsequent window instead of dB selectthe abbreviation VSWR and additionallyselect parameter S11 instead of S21. VNWAnow shows the locally measured standingwave ratio in the frequency range of themeasurement as a blue curve. In the inter-ests of better readability, one or more so-called frequency markers may be added.This allows any points of the curve to be“approached” in order to be able to readthe measurement frequency and the resultaccurately. For this purpose, a right clickwithin the grid frame on an empty area issufficient. This opens a context menu asshown in Fig. 63. Click on Add FrequencyMarker → Normal. The first frequency

Fig. 61: Selection menu for transferring data from a file or from Windows clipboard into themeasured value memory of VNWA


marker is then displayed, shown as a smalltriangle with an associated digit 1 above.The marker can be moved by left-clickingand holding the mouse button whilst mov-ing the mouse cursor along the trace. In theupper left corner of the main window,among other things, the corresponding fre-quency and the associated value of the as-sociated SWR are displayed in the samecolour as the curve, in this case in blue. Inthe example in Fig. 63, the frequencymarker is at 6.29 MHz, where an SWR val-ue s = 4.46 was measured. The describedprocedure sounds a bit complicated due toits detailed description. However, afterpractising the simple process of data trans-fer a few times, it is unlikely to cause anydifficulties. The measurement diagramsshown in VNWA can be saved and printedout. For this purpose the menu item File→Print has to be selected in the main win-dow of VNWA. The graphic can then besaved as an image file or output to a printer.

Fig. 62: Main window after importing a data set from the clipboard to the S11-measurementtrace


n FA-VA5 as USB measuringFront-end

USB measuring Front-end means that thePC software VNWA takes over the entirecontrol and evaluation of a measurement.In simple terms, the FA-VA5 in this case

only supplies the requested measurementvoltage for a frequency specified by VN-WA. Thus, for example, parameters of amulti-frequency measurement, such as thenumber of measuring points (instead of thelocally fixed 100 points) can be specified

within given limits. In the following sec-tions, a simplified measurement explainsthe procedure as an example, with valuesto be determined for SWR and impedance. Step 1: Definition of the measuringparametersFirst the start and stop frequencies have tobe entered. In the main window of VNWA(Fig. 56), this can easily be done by dou-ble-clicking on one of the frequencies dis-played below the bottom of the Grid: left=Start, middle=centre or right=Stop fre-quency. The frequency window (Input)will open and allows you to enter the startand stop frequency of a multi-frequencypass. Note the decimal point as a divisionbetween pre- and post-decimal places. Forthe example, 6MHz to 10MHz was select-ed in Fig. 64. Further parameters are de-vice-specific and can be set for the FA-VA5 via the familiar window according toFig. 58 (Settings → Sweep). In addition tothe Number of Datapoints, one of the threeFA-VA5 (sweep mode) accuracy levelscan be selected: fast, standard, or precise.In addition, another delay per measuredvalue can be set (additional delay). Thiscan be useful when measuring low-fre-quency filters, which have a long settlingtime. VNWA calculates the resulting timefor the multi-frequency measurement. The

Fig. 63: Context menu when adding a frequency marker; the data of marker 1 (Arrow) can beseen in the upper left corner of the diagram (framed in red).


window can be closed here with the de-fault values and all measurement parame-ters are now defined. Step 2: CalibrationShort, Open, Load (SOL) Calibration ismandatory before any measurements.Otherwise, contrary to the local mode ofthe FA-VA5, no SOL correction will takeplace by the VNWA Application. The SOLcalibration elements available for the FA-VA5 can be used. For the use of mastercalibrations and the like refer to the VN-WA Help Document [2]. If the calibrationset BX-245-SOL is used, its individuallymeasured values can be loaded once via aparameter file. This file can be download-ed via the link listed on the instructionleaflet supplied with the BNC Calibrationkit. The path and the name of the CKF filecan be specified using Cal Kit → Load asshown in Fig. 65. After confirmation therelevant Calibration Kit parameters areused in the subsequent calibration. Cali-bration for the specified measuring param-eters is done via the menu item Measure→ Calibrate. The opening window in Fig.65 shows the state of the current calibra-tion in the form of red circles, in this caseit is uncalibrated. By left clicking on theShort button another window appears,which now asks to connect the Short cal-

ibration element to the FA-VA5. After itsconnection and confirmation, a measure-ment cycle starts, the circle turns green,with red M in the middle. Similarly, thecalibration for Open and Load is carriedout, the window can then be closed. In themain window of VNWA, the abbreviationCal should now appear at the bottom left.The advantage of this calibration proce-dure is that it has now been calibrated ex-actly to the current measurement configu-ration in terms of both hardware andmeasurement parameters. For example, ifan extension cable is used, this cable issimply “calibrated in”. Step 3: Carrying out themeasurementAfter calibration and connection of the testobject, taking the actual measurement is asimple matter. In the main window, clickon the Single Sweep button (bottom right)to start a single multi-frequency measure-ment. As a result, the measured values arein memory S11. The display settings fromthe example result in a view as shown inFig. 66. If you want to continuously trackthe result of an adjustment on the measure-ment object, ress the Continuous buttonand start repetitive sweep runs. This pro-cess can only be ended by pressing theContinuous button again.

Fig. 65: Calibration window of the VNWAsoftware prior to the start of the calibrationprocess

Fig. 64: Double-clicking on the correspondingSpan label in Fig. 42 opens this input windowfor entering the start and stop frequency


Step 4: Choice of display andcalculationOne of the strengths of VNWA is the ex-tensive possibilities for displaying andevaluating measurement results. In total,up to six different traces and their calcula-tion rules can be selected. After double-

clicking on the coloured S11 of an existingtrace in the main window of VNWA bot-tom left, a new window opens as shown inFig. 67. Among other things, it is possibleto define in detail which channel (trace)should be displayed with which meaning.In the example, the very simple settings

according to Fig. 67 apply. Only the valuefor the SWR calculated from S11 shouldbe displayed in blue. The reflection coef-ficient is displayed as a red curve in theSmith chart. With regard to the extensivefurther possibilities, reference is againmade to the VNWA Help document [2].Finally, the final step is meaningful for-matting of the selected output traces. Inthe main window (Fig. 66), colour-coded,top left shows the scale for each trace. Onthe right side there is, again colour coded,the specification of the reference level orvalue. Both can be changed in a windowwhich opens by double-clicking on one ofthe values. The reference level can also bemoved by clicking and holding. In the ex-ample of Fig. 67, the lowest line in the di-agram corresponds to the value s = 1. Thenext line up means s = 2 etc. The flexibil-ity of the scaling and positioning servesfor better readability. As long as scalingand reference levels are known, it does notmatter where the curves are positioned inthe grid, they can be moved. A handy fea-ture and a good starting point is autoscale,which can be done by left-clicking on thetrace scaling factor. This sets the grid scaleto sensible values which improves read-ability. Finally, frequency markers help tobetter examine individual values along themeasurement traces. As mentioned earlier,

Fig. 66: Result of a measurement run after calibration (arrow).


right-clicking in an empty area within thegrid frame will bring up various markerfunctions. In the example, a marker wasset to the resonant frequency ƒ = 8.052MHz of the DUT (the imaginary part ofthe reflection coefficient is zero here). TheVSWR at this frequency is s = 1.45. We wish you great success and fun in set-ting up and operating the FA-VA5 AntennaAnalyzer.

[email protected]@sdr-kits.net

Fig. 67: The menu Display Setup offers a high degree of flexibility in the selection of the dis-played measurement results; here only two traces are activated.


References[1] FUNKAMATEUR reader service, Majakowski-

ring 38, 13 156 Berlin, Germany, Tel. ++49-304466 9472, Fax 9469; www.box73.de or www.box73.com→ BX-245-SOLThe FA-VA5 Kit and the 600MHz BNC Calibra-tion Kit are also available from SDR-Kits, Office11, Hampton Park West, Melksham, SN12 6LHUnited Kingdom. www.SDR-Kits.net

[2] Baier, T., DG8SAQ: VNWA Software. Down-load link: http://www.SDR-Kits.net/DG8SAQ/vnwaupdate.php?path=installer&source=Sdr-kitsDocumentation links https://SDR-Kits.net/ DG8SAQ-VNWA-software-documentation-user-guide

[3] USB UART Bridge Driver Download Page,CP210X: www.silabs.com/products/development-tools/software/usb-to-uart-bridge-vcp-drivers

Scattering parameters

The S11 parameter relevant for the FA-VA5, ispart of a group of measured parameters sup-ported by the VNWA software. Related param-eters are S12, S21 and S22 (not consideredhere). The letter S stands for scattering param-eters. These describe the behaviour of net-works by means of wave amplitudes andphase. A two-port network has one input andone output (e.g., amplifier or attenuator). It isnow possible to measure, for example, whichportion of a wave is transmitted from the inputto the output (S21) or from the output back tothe input (S12). Furthermore, the proportion ofa reflected wave at the input (S11) or at theoutput (S22) can be measured. The four pa-

rameters S11, S21, S12 and S22 describe atwo-port linear network completely and with-out internal details of the “black box” beingknown. The software VNWA has been createdfor the VNWA-3 Vector Network Analyzerhardware, which has a signal output (with re-flection sensor) as well as a separate signal in-put. Therefore, besides S11, also S21 (trans-mission) can be measured. By interchangingthe input and output of the Device under Test(DUT), the remaining two scattering parame-ters S12 and S22 can be determined. Anten-nas and other devices have only one port with2 connecting wires. The antenna analyzer FA-VA5 has therefore only one measuring socket.So only the reflection at the input can be mea-sured (S11). This explains why only the S11data memory is of interest here. S11 repre-sents a complex reflection factor consisting ofreal and imaginary parts. From S11, a varietyof other parameters such as the standingwave ratio and the impedance Z can be math-ematically derived. The presentation of resultsis often done in a so-called Smith diagram,with the help of which also matching problemsand the like can be solved graphically.

S21

S12

S22S11

Zweitor

http://www.SDR-Kits.net/DG8SAQ/vnwaupdate.php?path=installer&source=Sdr-kits

http://www.SDR-Kits.net/DG8SAQ/vnwaupdate.php?path=installer&source=Sdr-kits

https://SDR-Kits.net/DG8SAQ-VNWA-software-documentation-user-guide

https://SDR-Kits.net/DG8SAQ-VNWA-software-documentation-user-guide


Parts ListAbbreviation Component Number CommentX1 BNC socket 1S2 … S4 pushbutton 3(S2 … S4) Button for push button switch 3S1 slide switch 1G1, G2 Battery holder for AA cell 2SG1 piezo buzzer 1USB USB module 1 Mica washer 1 Fitted between USB module / PCB Graphic display pre-assembled with LED Backlight 1 LED backlight requires soldering Female header, 20-pin 1 for the display Socket strip, 3-pin 2 for the display Main PCB SMD- 1 components fitted Enclosure 1 consists of upper and lower shell Rubber foot 4 Cylinder screw M3 × 4 4 for mounting the Main PCB Countersunk screw M3 × 4 4 for assembling Enclosure Cardboard strip 1 width = 7 mm, for display adjustmentAssembly and User Manual 1 this manualType Label – self adhesive 1 Fit on bottom of EnclosureSOL set 50 Ω Termination 1 Manufacturer is Telegärtner BNC connector 2

AppendixVersion history

Ver E 1.0 1st editionVer E 1.1 table 1, page 11, 12Ver E 1.2 6-pin header obsoletVer E 1.3 New menu functions

provided in firmwareversion 1.09 added inchapters Operation mo-de and Setting mode.


n SHORT-Element

Not needed

1 1 5

6

7

8

22

3

3

4

Not soldered Carefully soldered

OPEN element ready for use

SHORT is ready for use

Slide the centre pin with the wire until itclicks into place. Remove the wire.

Slide the centre pin with the solderedwire until it clicks into place.

Bent and cut

Solder here

Scrape surface metal (2 x 2 mm)

Well done

Not needed

n OPEN element BX-245

Box 73 Amateurfunkservice GmbHMajakowskiring 3813156 BerlinGermany

6th August 2019Please report problems to [email protected]

Order no. BX-245

When disposing of this product, pleaseobserve the regulations for the handlingof electronic waste. Electronic devices,batteries and components do not belongin household waste. For further informa-tion please check www.box73.de orwww.box73.com

vector antenna analyzer fa-v a5 - box73.de€¦ · vector antenna analyzer fa-v a5 ver e 1.3...

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