The N2PK Vector Network Analyzer

(N2PK VNA)

Paul Kiciak, N2PKPaul Kiciak, N2PK

What Does “Vector” Mean?!! Vector: magnitude & direction (angle)Vector: magnitude & direction (angle)!! Scalar: magnitude onlyScalar: magnitude only!! Scalars: 22 MPH, 50 ohms, 6 dBScalars: 22 MPH, 50 ohms, 6 dB!! Vectors:Vectors:

"" Wind: 22 MPH from SSEWind: 22 MPH from SSE"" Impedance: 25 ohms @ Impedance: 25 ohms @ --12 degrees12 degrees"" Reflection: 0.50 @ 155 degrees Reflection: 0.50 @ 155 degrees

!! Polar vs. Rectangular Vectors Polar vs. Rectangular Vectors "" Equivalent representationsEquivalent representations"" Polar: 25 ohms @ Polar: 25 ohms @ --12 deg.12 deg."" Rectangular: 24.45Rectangular: 24.45--j5.20 ohmsj5.20 ohms

01/22/07 N2PK

Some “Networks”!! General:General:

"" Black box: don’t care what’s insideBlack box: don’t care what’s inside"" ‘Ports’ instead of ‘inputs’ & ‘outputs’‘Ports’ instead of ‘inputs’ & ‘outputs’"" Number of Parameters: N*N for NNumber of Parameters: N*N for N--port port "" DUT: NDUT: N--Port Device Under TestPort Device Under Test"" 22--port: port:

!! Examples:Examples:"" 11--ports: antenna, R, L, Cports: antenna, R, L, C"" 22--ports: filters, pair of antennasports: filters, pair of antennas"" 44--port: directional couplerport: directional coupler

01/22/07 N2PK

What Does A VNA Measure?!! Reflection Parameters:Reflection Parameters:

"" Impedance*, Admittance*, SWR, Return Loss, Reflection CoefficieImpedance*, Admittance*, SWR, Return Loss, Reflection Coefficient*nt*"" Equivalent series & parallel R, L, CEquivalent series & parallel R, L, C"" QQ

!! Transmission Parameters: Transmission Parameters: "" Gain*, dBGain*, dB"" Group delay in secondsGroup delay in seconds

!! Components:Components:"" Antennas, coax, …Antennas, coax, …"" Inductors, capacitors, resistorsInductors, capacitors, resistors"" Filters: crystal, LC, …Filters: crystal, LC, …"" Amplifiers & attenuatorsAmplifiers & attenuators"" Duplexers, diplexers, directional couplers, …Duplexers, diplexers, directional couplers, …"" Diodes, transistors, …Diodes, transistors, …

01/23/07 N2PK* Complex (vector)

01/22/07 N2PK

HP 8410A – late 60’s, 110 MHz-12.4 GHz HP 8753C – late 80’s, 300 kHz-6 GHz

Some VNA History

Agilent E5071C – current, 9 kHz-3 GHz N2PK VNA (by VE3MM) – current, 50 kHz-60 MHz

Key Specs!! Frequency Range: Frequency Range:

"" VNA: 50 kHz VNA: 50 kHz –– 60 MHz, 0.034 Hz steps60 MHz, 0.034 Hz steps"" LO source: <1 Hz with HiLO source: <1 Hz with Hi--Z loadZ load

!! Detectors options:Detectors options:"" Single or dualSingle or dual"" Slow, single rate (original)Slow, single rate (original)"" Fast, variable rateFast, variable rate

!! Fast Detector Rates:Fast Detector Rates:"" 10 rates, software selectable10 rates, software selectable"" 3.5 3.5 freqsfreqs/sec @ slowest rate/sec @ slowest rate"" 900 900 freqsfreqs/sec @ fastest rate/sec @ fastest rate

!! Dynamic Range (w/o averaging):Dynamic Range (w/o averaging):"" >110 dB dynamic range @ slowest rate>110 dB dynamic range @ slowest rate"" 90 dB dynamic range @ fastest rate90 dB dynamic range @ fastest rate

!! Effective Detector RF Bandwidth:Effective Detector RF Bandwidth:"" 7 Hz @ slowest rate7 Hz @ slowest rate"" 3.4 kHz @ fastest rate3.4 kHz @ fastest rate"" Virtually immune to external signals (antenna testing) Virtually immune to external signals (antenna testing)

!! No adjustmentsNo adjustments!! PC software controlled via Parallel port or USB portPC software controlled via Parallel port or USB port

"" Standalone version by VE7IT Standalone version by VE7IT –– builtbuilt--in controller & displayin controller & display!! Homebrew: $250 for a single detector versionHomebrew: $250 for a single detector version

01/22/07 N2PK

How Does It Work?

!! RF & LO Direct Digital Synthesis (DDS) SourcesRF & LO Direct Digital Synthesis (DDS) Sources!! Linear Detector: Synchronous Direct Conversion to DC Linear Detector: Synchronous Direct Conversion to DC !! Sequential Sequential QuadratureQuadrature: 0 deg, then 90 deg, & the difference is VERY accurate: 0 deg, then 90 deg, & the difference is VERY accurate!! 24 bit Analog to Digital Converter (ADC)24 bit Analog to Digital Converter (ADC)

01/22/07 N2PK

RF

LO

F+ aliasesO RF

LO

F+ aliasesO

RF

LO

F + aliasesO

Expanded N2PK VNA

01/22/07 N2PKOptional Transverter for VHF/UHF

(F + aliases)O

Hardware

01/22/07 N2PK

Single Detector PCB VE3IVM Dual Detector PCB

Reflection Bridge PCB

Calibration standards

Power Board

01/22/07 N2PK

SM0CFO+SM6PXJ AG4AY

Some N2PK VNAs

W8WWV OZ1DUG VE7IT - standalone

GM4SEK

Software!! N2PK DOS based (programs function in DOS or Windows) N2PK DOS based (programs function in DOS or Windows)

"" ReflectionReflection## Open/Short/Load (OSL) calibrationOpen/Short/Load (OSL) calibration## Optional LowOptional Low--Loss Capacitor (LLC) standard for lowLoss Capacitor (LLC) standard for low--loss & Hiloss & Hi--Q Q DUTsDUTs

"" TransmissionTransmission## Through calibration (assumes 50 ohm source and load impedances)Through calibration (assumes 50 ohm source and load impedances)

"" Reflection & TransmissionReflection & Transmission## OSL and Through OSL and Through –– real time simultaneous reflection and transmissionreal time simultaneous reflection and transmission## Optional 12Optional 12--term error correction with Sterm error correction with S--Parameter Test SetParameter Test Set

"" Special Test Programs:Special Test Programs:## VNA RF SelfVNA RF Self--Test (Vs, Zs, Test (Vs, Zs, ZdZd))## Crystals (Fs, Crystals (Fs, FpFp, , RmRm, Lm, Cm, Co, Q), Lm, Cm, Co, Q)## Coax (Coax (ZoZo, attenuation constants), attenuation constants)## Component modeling (future)Component modeling (future)

!! Windows programs (all do reflection or transmission & good graphWindows programs (all do reflection or transmission & good graphics)ics)"" Exeter (W8WWV)Exeter (W8WWV)"" VNA4win (GM4PMK & GM3SEK)VNA4win (GM4PMK & GM3SEK)"" WINVNA (OZ1DUG)WINVNA (OZ1DUG)

!! Windows Data File ViewersWindows Data File Viewers"" IVMan Lite IVMan Lite (VE3IVM)(VE3IVM)"" ZplotsZplots (AC6LA’s Excel app)(AC6LA’s Excel app)

01/22/07 N2PK

01/22/07 N2PK

N2PK DOS - Reflection N2PK DOS - TransmissionSome Test Results

Exeter - Reflection VNA4win - Transmission

How Good Is It?! Correlations with commercial VNAs

RsRs, ohms Cs,, ohms Cs, pFpF

-------------------------------------- --------------------------------------

F N2PK 8753C Delta N2PK 8753C DeltaF N2PK 8753C Delta N2PK 8753C Delta

---- ---------- ---------- ---------- ---------- ---------- ----------

1 25.20 19.25 +5.95 198.6 199.3 1 25.20 19.25 +5.95 198.6 199.3 --0.70.7

10 24.98 24.97 +0.01 199.2 199.1 +0.110 24.98 24.97 +0.01 199.2 199.1 +0.1

20 24.96 24.97 20 24.96 24.97 --0.01 199.9 200.1 0.01 199.9 200.1 --0.20.2

30 24.97 24.98 30 24.97 24.98 --0.01 201.1 202.1 0.01 201.1 202.1 --1.01.0

40 24.98 24.95 +0.03 202.9 202.9 0.040 24.98 24.95 +0.03 202.9 202.9 0.0

50 24.98 25.00 50 24.98 25.00 --0.02 205.0 206.2 0.02 205.0 206.2 --1.21.2

60 24.97 25.00 60 24.97 25.00 --0.03 207.8 208.6 0.03 207.8 208.6 --0.80.8

Reflection Transmission

! Jack Smith, K8ZOA (http://www.cliftonlaboratories.com/faq.htm)"If you are interested in filter analysis, you should really look into the N2PK VNA. There's a Canadian ham selling PCBs for it. I have one (one of the W8WWV group purchase) and it's an excellent piece of gear--within its frequency range fully as accurate as any of my HP network analyzers. "

! Ian White, GM3SEK, (http://lists.contesting.com/_rfi/2004-06/msg00002.html)“The N2PK vector network analyzer has superb accuracy, even by professional standards; "

! Ian White, GM3SEK, (http://lists.contesting.com/archives//html/Towertalk/2006-12/msg00937.html)"Compared with amateur-market instruments that rely on build quality alone, the use of calibrations takes the N2PK into the professional league for accuracy. "

! Rudy Severns, N6LF, (http://www.antennasbyn6lf.com/files/160_m_vertical_measurements.pdf)"The impedance measurements were straight forward. These measurements were made using an N2PK vector network analyzer. Crosschecking with an HP 3577A analyzer, the measurements appear to be better than 1% which is more than adequate. "

01/30/07 N2PK

Publications

!! Pat Hawker, G3VA, "Technical Topics", Sept. 2004,Pat Hawker, G3VA, "Technical Topics", Sept. 2004, RadComRadCom!! Ian White, G3SEK, photo of his VNA on Ian White, G3SEK, photo of his VNA on RadComRadCom cover, Oct 2004cover, Oct 2004!! Ian White, G3SEK, "In Practice" Oct 2004, Ian White, G3SEK, "In Practice" Oct 2004, RadComRadCom, ,

http://http://wwwcowwwco..ukuk/g3sek/in/g3sek/in--pracprac/61_62_/61_62_radcomradcom_oct04._oct04.pdfpdf!! A photo of the VNA PCB of the RF DDS, cover of the RSGB 2003A photo of the VNA PCB of the RF DDS, cover of the RSGB 2003--

2004 Annual Report2004 Annual Report!! Giancarlo ModaGiancarlo Moda, I7SWX, April 2004, Radio, I7SWX, April 2004, Radio RivistaRivista, "IL VECTOR , "IL VECTOR

NETWORK ANALYZER DI N2PK“NETWORK ANALYZER DI N2PK“!! BobBob CerretoCerreto, WA1FXT, January 2006, Bacon Bits Quarterly , WA1FXT, January 2006, Bacon Bits Quarterly

Newsletter, Newsletter, http://www.http://www.fpqrpfpqrp.com/BBITS/BBQ0106.PDF .com/BBITS/BBQ0106.PDF and The and The QRP Quarterly, Spring 2006QRP Quarterly, Spring 2006

!! JohnJohn DevoldereDevoldere, ON4UN, "Low, ON4UN, "Low--BandBand DXingDXing", 4th Edition, Section ", 4th Edition, Section 3.6.9, pg 113.6.9, pg 11--3434

!! Dave Roberts, G8KBB, "USB Interfacing“, Oct. 2005, Dave Roberts, G8KBB, "USB Interfacing“, Oct. 2005, RadComRadCom

01/22/07 N2PK

Web Resources!! AgilentAgilent -- VNA Fundamentals:VNA Fundamentals:

http://cp.literature.http://cp.literature.agilentagilent.com/.com/litweblitweb//pdfpdf/5965/5965--7707E.7707E.pdfpdf!! Paul Kiciak, N2PK Paul Kiciak, N2PK –– documentation, build info, DOS software:documentation, build info, DOS software:

http://n2pk.comhttp://n2pk.com!! Greg Greg OrdyOrdy, W8WWV , W8WWV -- build info: build info:

http://www.seedhttp://www.seed--solutions.com/solutions.com/gregordygregordy/Amateur Radio/Experimentation/N2PKVNA/N2PKVNA./Amateur Radio/Experimentation/N2PKVNA/N2PKVNA.htmhtm!! Ivan Ivan MakarovMakarov, VE3IVM , VE3IVM -- build info:build info:

http://www.http://www.makarovmakarov.ca/.ca/vnavna..htmhtm!! Ian White, GM3SEK Ian White, GM3SEK -- build info:build info:

http://www.ifwtech.co.uk/g3sek/inhttp://www.ifwtech.co.uk/g3sek/in--prac/bestprac/best--of.htm#n2pkof.htm#n2pk!! Dave Roberts, G8KBB, VNA USB interface:Dave Roberts, G8KBB, VNA USB interface:

http://http://ukuk.geocities.com/g8kbb@.geocities.com/g8kbb@btinternetbtinternet.com/.com/newfilenewfile..htmhtm!! Lawrence Lawrence GlaisterGlaister, VE7IT , VE7IT –– standalone VNA: N2PK VNA PCB + custom controller & displaystandalone VNA: N2PK VNA PCB + custom controller & display

http://members.http://members.shawshaw.ca/.ca/swstuffswstuff//vnavna.html.html!! Windows software:Windows software:

"" Exeter, Greg Exeter, Greg OrdyOrdy, W8WWV:, W8WWV:http://www.seedhttp://www.seed--solutions.com/solutions.com/gregordygregordy/Software/Exeter./Software/Exeter.htmhtm

"" VNA4win, Roger Blackwell, GM4PMK, & Ian White, GM3SEK:VNA4win, Roger Blackwell, GM4PMK, & Ian White, GM3SEK:http://www.http://www.marsportmarsport.org..org.ukuk/vna4win/index./vna4win/index.htmhtm

"" WinVNAWinVNA, , JoakimJoakim Soya, OZ1DUG:Soya, OZ1DUG:http://www.http://www.plankerplanker..dkdk/oz6frs/2004//oz6frs/2004/ProjekterProjekter//IgangIgang/N2PK/N2PK_VNA./N2PK/N2PK_VNA.htmhtm

"" IVMan LiteIVMan Lite data file viewer, Ivan data file viewer, Ivan MakarovMakarov, VE3IVM:, VE3IVM:http://www.http://www.makarovmakarov.ca/.ca/vnavna__ivmanliteivmanlite..htmhtm

"" ZplotsZplots Excel data file viewer, Dan Excel data file viewer, Dan MacguireMacguire, AC6LA:, AC6LA:http://www.ac6la.com/http://www.ac6la.com/zplotszplots.html.html

!! N2PKN2PK--VNAVNA YahoogroupYahoogroup (almost 500 members):(almost 500 members):http://groups.yahoo.com/group/N2PKhttp://groups.yahoo.com/group/N2PK--VNAVNA 01/23/07 N2PK