fieldfox handheld fieldfox handheld education series …€¦ · · 2012-10-25•measure...

© 2012 Agilent Technologies

FieldFox Handheld

Education Series Part 2:

Techniques for Precise

Cable and Antenna

Measurements in the Field

Tom Hoppin

Business Development Engineer

FieldFox Handheld Education Series

• Interference Testing

• Cable and Antenna Measurements

• Calibration and Alignment

• Time Domain Measurements

• Precise Power Measurements

www.agilent.com/find/FieldFoxWebcasts

© 2012 Agilent Technologies © 2012 Agilent Technologies

Techniques for Precise Cable and

Antenna Measurements in the Field

October 24, 2012


Outline

• Why is Cable and Antenna Testing Important?

• Cable Testing

• Antenna Testing

• Distance-to-Fault (DTF) Measurements

• FieldFox Calibration

Image courtesy of John Arthur, Wireless EDGE


Why is Cable and Antenna Testing Important?

• Verify transmission performance (line sweeping)

• Measure installed antenna performance and isolation

• Determine the location of damaged components

Images courtesy of John Arthur, Wireless EDGE

Types of cable damage

• Failed seal at a cable splice (liquid ingress)

• Failed solder joint at connector interface

• Cut, crushed and/or weather-induced cracks

• Minimum bend radius exceeded


Line Sweeping and Distance-to-Fault (DTF)

Measured line sweep

Calculated DTF

X-band horn

antenna

Coaxial

cable

FieldFox

N9918A


Cable Loss Measurement Techniques

2-port

loss measurement

1-port

loss measurement

Open or short

Power sensor-based

loss measurement

Power

sensor

USB

cable


Cable Loss Measurement Examples

2-port and 1-port cable loss

Open or

short


Antenna Properties

• Return loss (dB)

• Voltage standing wave ratio (VSWR)

• Antenna-to-antenna Isolation

• Gain

• Efficiency

Return loss (dB) VSWR

FieldFox

Special

equipment


Antenna-to-Antenna Isolation

Copyright J M Briscoe and licensed for reuse under

the Creative Commons License.

Antenna

#1

Antenna

#2

Insertion loss

(2-port)

Isolation

FieldFox


Antenna-to-Antenna Isolation Measurement

900 MHz 2400 MHz

Insertion loss (2-port)

FieldFox


What is a Distance-to-Fault (DTF) Measurement?

Measurement technique to determine the location of problems

along a cable or transmission line

Input

pulseReflected

pulse

Transmitted

pulse

Damaged

cable

)1 ( 1

VF

22(meters) DTF

cable

tripround

cable

tripround

r

r

c

v

ctimev

time

material ofconstant dielectric relative

light of speedc

r


DTF Measurement

“Velocity

factor” (VF)

Cable Adapter Cable 50-ohm

load4 m 9.8 m

End of

cable

(M2)

(M3)

(M2)(M3)

FieldFox

(M1)


DTF Multiple Reflections

(M4)

(M5)

(M4)(M5)

Open

50-ohm

Open /

50-ohm

Adapter

• Multiple reflections may

create additional responses

past the cable end

• Swap the load from open to

50-ohm, observe changes in

response

FieldFox

End of cable


Entering Cable Parameters

• Manual entry

• Select/create cable file

RG8U cable specs

FieldFox DTF cable spec menu


Application Example: Estimating Velocity Factor

VF = ?

OpenFieldFox


Application Example: Distributed Antenna System (DAS)

Directional

coupler #1

Directional

coupler #2

Directional

coupler N

Antenna

#1

Antenna

#2

Antenna

N

CU

CU=Central unit

DAS techniques can

• Extend signal coverage

• Reduce signal fading

• Reduce system cost

DAS troubleshooting can result in complex DTF measurement

DAS verification is made with return loss measurement


Application Example: DAS Measurement

Baseline Reported problem

Directional

coupler #1

Directional

coupler #2

Antenna

#1

Antenna

#2

FieldFox

DTF


Application Example: DAS Measurement

Directional

coupler #1

Directional

coupler #2

Antenna

#2 Antenna

#1 Port

FieldFox

DTF

50-ohm

or open

(common

input)

DTF from antenna #1

DTF from antenna #2

Coupler #1

Open

Coupler #2

Open

Isolate reflections by measuring DTF

from antenna port(s)

DirectIsolated

Antenna #1

• FieldFox to coupler: 1.4 m

• FieldFox to common input: 3.8 m

• Coupler to common input: (3.8 - 1.4) = 2.4 m

(same as before)


Measured Frequency Span and Resolution

DTF with 1 GHz span

DTF with 6 GHz span

Wide

frequency

span

Improved

distance

resolution

Lowpass mode

• Highest resolution

• Requires broadband DUT (i.e. cable)

Bandpass mode

• Lower resolution

• Band-limited DUT (filter, antenna)


Maximum DTF Distance

BW2

Points VF Distance DTF Max.

c

range frequency BW

points data of # Points

light of speed c

FactorVelocity VF

Set distance

FieldFox distance menu


FieldFox Calibration Requirements

Factory calibration User calibration

Certificate of

calibration

Adapter

Jumper

cable

Calibration plane

Calibration plane

Re-calibration

recommended

12 to 18 months

Frequent

calibration


Calibrating for 1-Port Measurements

CalReady

(built-in)

Calibration plane

Factory

calibrated

Adapter

Jumper

cable

Calibration

plane

QuickCal

Open Load*

* Load

optional

Calibration

plane

Mechanical

Open Load

Requires mechanical

cal kit

Adapter

Jumper

cable

Short


Calibrating for 2-Port Measurements

Calibration plane

Factory

calibrated

Calibration

plane

Open Load*

* Load

optional

CalReady

(built-in)

QuickCal

Jumper

cable

Open Load* Thru

1 2

Mechanical cal requires

O, S, L during step 1

Adapter


FieldFox Guided Calibration – Cal Wizard

• FieldFox recommends calibration type

• Simple setup process

• Cal Wizard for step-by-step connections


Combination Analyzer: 10 Instruments in 1

Cable and antenna analyzer

30 kHz to 26.5 GHz

Full 2-port vector network

analyzer with time domain

analysis, 30 kHz to 26.5 GHz

Spectrum analyzer, with full-

band tracking generator

5 kHz to 26.5 GHz

Power meter

5 kHz to 26.5 GHz

Independent signal generator

30 kHz to 26.5 GHz

Vector voltmeter, 2-port

30 kHz to 26.5 GHz

Interference analyzer

Variable DC source and

current monitor Light weight: 6.6 lbs (3.0 kg)

Long battery life: 3.5 hrs

Bright display: 6.5 inch TFT

MIL-PRF-28800 F Class 2

MIL-STD-810G, 511.5, Proc 1Built-in GPS receiver Frequency counter

25


FieldFox Accessories

N9910X-810, type N(m) to N(m), 6 GHz

Waveguide

Type N, 7/16

Coax, 4-in-1

Other cal kits available

N9910X-709, 3.5 mm(f) to 3.5 mm(f), 26.5 GHz

N9910X-704, type N(m) to TNC(f), 13 GHz

Calibration kits

Phase stable test cables

Coax, 3-in-1

3.5 mm, Type N X-band, P-band, K-band


FieldFox Analyzer Characteristics

N9912/3/4/5/6/7/8A RF and microwave combination analyzers

N9923/5/6/7/8 RF and microwave vector network analyzers

N9935/6/7/8A RF and microwave spectrum analyzers

Top frequency ranges from 4 GHz – 26.5 GHz

• Carry precision with you - Agilent-quality measurements

• Full amplitude accuracy of ±0.6 dB at turn-on, -10 to +55 oC

• Weather resistant, MIL-PRF-28800F Class 2 design

• 6.6 pounds (3 kg)

• Built-in GPS

• 3.5 hour battery life


Conclusions

• Introduced Cable and Antenna Testing and its importance for optimizing

and troubleshooting transmission systems and antennas

• Discussed measuring cable insertion loss using 1-port and 2-port

techniques

• Discussed antenna parameters and field measurements

• Introduced Distance to Fault (DTF) measurement and concepts

• Reviewed the different types of user calibrations available on the

FieldFox


For More Information

Web: www.agilent.com/find/FieldFox

Literature:- Techniques for Precise Interference Measurements in the Field, application note,

literature number 5991-0418EN

- Techniques for Precise Cable and Antenna Measurements in the Field, application

note, literature number 5991-0419EN

- FieldFox Handheld Analyzers, brochure, literature number 5990-9779EN

Thank you for your time

Questions?

First in a series of monthly application webcasts

• Sept 26, 2012: Interference Testing

• Oct 24, 2012: Cable and Antenna Measurements

• Nov 28 2012: Calibration and Alignment

• Jan 23 2013: Time Domain Measurements

• Mar 27 2013: Precise Power Measurements

Registration: www.agilent.com/find/FieldFoxWebcasts

http://www.agilent.com/find/FieldFox

http://www.agilent.com/find/FieldFoxWebcasts

fieldfox handheld fieldfox handheld education series …€¦ · · 2012-10-25•measure...

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