Post on 07-Apr-2018
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Understanding Cable & Antenna Analysis
AGENDA
Introduction Common Problems FDR vs TDR Propagation Velocity Return Loss/VSWR Cable Loss
Distance to Fault (DTF) Test Examples Interpretation Sitemaster Family Summary
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Introduction
Cable and Antenna system plays a crucialrole of the overall performance of a BaseStation system.
Degradations and failures in the antennasystem may causepoor voice quality or dropped calls.
result in loss of revenue. Problematic base stations can be replaced Cable and antenna systems not so easy to
replace.
Field technicians troubleshoot the cableand antenna system and ensure theoverall health of the system
Field technicians today rely on portablecable and antenna analyzers to analyze,troubleshoot, characterize, and maintainthe system.
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Common RF & Microwave Problems
Installation problemsPoor grounding
Excessive bendsCrimping, Crushing and
Deforming
Routine MaintenanceDamaged/Dented Ground Shield
Kinks in the cableBroken center conductor
WeatherExcessive Moisture like snow,
rainSea waterCorrosion
Mis-installationPoor center pin contactLow quality connectors
Poor weather proofingLoose connectors
WeatherWater ingress
Corroded connectorsExtreme temperatures plane
landing/cruising
Mis-installationShipping damage
Out of Specification
Routine MaintenanceStorm damage
Extreme temperatures
Cables Connectors Antennas
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Reflection
ImpedanceMismatch
Insertion Loss
System performance problems are typically seen in
one of two ways:Excessive Reflections More common
Numerous causes
Excessive Insertion Loss
Less common
Typically due to water in cable
Common RF & Microwave Problems
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Return Loss/Reflection Coefficient
Return Loss = - 20Log (reflection coefficient)
Signal PowerFrom Source = Pi
Impedance
Not Matched,Not 50 Ohms
Reflected Poweris Proportional to
Impedance Mismatch
Reflection Coefficient = = Pr / Pi
Pi
Pr
Expressed in Voltage Terms, = Er / Ei
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Standing Waves, SWR
Signal Voltage
From Source = Ei
DUT Input
ImpedanceNot Matched,Not 50 Ohms
LowFrequency
ReflectedSignal Voltage = Er
MiddleFrequency
High
Frequency
The ratio of maximum to minimum isVSWR.
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Mismatch Equations
V max V minVSWR = V max / V min = (1 + ) / (1 - )
Reflection Coefficient = = Er / Ei =VSWR -1
VSWR +1
Return Loss = RL = - 20Log ()
Return Loss = -20LogVSWR -1
VSWR +1
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Return Loss Display
Displays ratio of Reflected Power to Reference power in dB. Easier to compare small and large signals on a Logarithmic scale.
Scale is usually 0 to 60 dB
0 represents short
60 represents close to perfect match
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VSWR Display
VSWR displays the match of the system linearly. Measures the ratio of voltage peaks and valleys.
The greater this number is, the worse the match is.
A perfect or ideal match in VSWR terms would be 1:1
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VSWR Vs Return Loss Plot
The two graphs illustrate the relationship between VSWR and Return Loss.26 dB RL 1.1 VSWR
1.0
1.5
2.0
2.5
3.0
1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200
Limit : 1.42
M1 M2M3
VSWRAntennaVSWR
Model: MT8212E Serial #: 01007099Date: 09/03/2010 Time: 03:01:16Std: --- Channel: N/AResolution: 259 FlexCAL:ON(COAX) CW: OFF
VS
WR
Frequency (1700.0 - 2200.0 MHz)
M1: 1.439 @ 1844.161 MHz M2: 1.419 @ 2081.387 MHz M3: 1.104 @ 1913.504 MHz
-60
-50
-40
-30
-20
-10
0
1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200
Limit : -15.0
M1 M2M3
Return LossAntenna1
Model: MT8212E Serial #: 01007099Date: 09/03/2010 Time: 02:59:37Std: --- Channel: N/AResolution: 259 FlexCAL:ON(COAX) CW: OFF
dB
Frequency (1700.0 - 2200.0 MHz)
M1: -15.01 dB @ 1844.161 MHz M2: -15.27 dB @ 2081.387 MHz M3: -25.98 dB @ 1913.504 MHz
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Cable Loss
Measures the energy absorbed, or lost, by the transmission line in dB/meter
or dB/ft. Different transmission lines have different losses, and the loss is frequency
and distance specific.
The higher the frequency or longer the distance, the greater the loss.
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Distance-To-Fault
Reveals the precise fault location of components in the transmission line
system. Helps to identify specific problems in the system
connector transitionsJumperskinks in the cable or moisture intrusion.
Passing DTF Plot Failing DTF Plot
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Distance-To-Fault
Maximum distance range & fault resolution is dependent upon frequency range
and number of data points.DTF Aid shows how the parameters are related.Horizontal range is increased by reducing frequency span or increasing numberof data points.
Fault resolution is inversely proportional to frequency rangeFault resolution improved by widening frequency span.
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Air Dielectric
Constant (er)
Vc
r
=
c= 3 x 108 m/sec
Propagation Velocity
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Fault Resolution and Display Resolution
Fault resolution is the system's ability to separate two closely spaced
discontinuities. If the fault resolution is 10 feet and there are two faults 5 feetapart, the instrument will not be able to show both faults unless FaultResolution is improved by widening the frequency span.
Fault Resolution (m) = 1.5 x 108 x vp /F
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Reference Plane
The reference plane defined for vector
measurements is the point at whichcalibration standards are applied.
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Low Cost, Phase Stable Cables
Phase stable Cables reach difficult locationswithout loss of accuracy.
Open/Short/Load Calibration must
be performed at the cables end.
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Precision Calibration Components
Standard N :> 35 dB
Precision N :> 42 dB
Precision 7/16:> 45 dB
Like any analyser, the quality of thecalibration components determines accuracy.
Terminations
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DC Pulse versus Frequency Sweep
Sources
SpectralDensity
f1 f2
FDR
TDR
Less than 2% of
TDR source energyis in the RF bands
FDR
FDR Versus TDR
TDR
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M1M2
Del M1-M2: .00 dB, .0 MHz
-35
-30
-25
-20
-15
-10
-5
800 810 820 830 840 850 860 870 880 890 900
Return Loss800 - 900 MHz (cal on)
dB
MHz
M1: -26.94 dB @ 857.4 MHz M2: -26.94 dB @ 857.4 MHz
M1 M2
Del M1-M2: 1.75 dB, 61.63 Feet
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
50 100
Distance To Fault0 - 150 Feet (cal on)
ReturnLoss(dB)
Feet
M1: -22.38 dB @ 46.51 Feet M2: -20.63 dB @ 108.14 Feet
-35
-30
-25
-20
-15
-10
-5
800 810 820 830 840 850 860 870 880 890 900
Return Loss800 - 900 MHz (cal on)
dB
MHz
M1 M2
Del M1-M2: 7.07 dB, 61.63 Feet
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
50 100
Distance To Fault0 - 150 Feet (cal on)
R
eturnLoss(dB)
Feet
M1: -27.33 dB @ 46.51 Feet M2: -20.26 dB @ 108.14 Feet
Frequency Domain Reflectometry
BEFORE AFTER
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Baseline The System
Record/Store DTF and Return Loss Data
M1 M2
-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
50 100
Distance to Fault - baseline0 - 140 feet (frequency = 800 - 1200 MHz)
ReturnLoss(dB)
Feet
M1: -36.97 dB @ 30.38 feet M2: -12.54 dB @ 112.86 feet
M1 M2
-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
800 850 900 950 1000 1050 1100 1150 1200
Return Loss - baseline800 - 1200 MHz (cal on)
dB
MHz
M1: -21.01 dB @ 806.2 MHz M2: -21.01 dB @ 902.3 MHz
Test Examples
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Loose Connector
Connector with pin gap problem
M1 M2
-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
50 100
Distance to Fault0 - 140 feet (frequency = 800 - 1200 MHz)
ReturnLoss
(dB)
Feet
M1: -26.70 dB @ 30.38 feet M2: -12.56 dB @ 112.86 feet
M1 M2
-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
800 850 900 950 1000 1050 1100 1150 1200
Return Loss - with pin gap800 - 1200 MHz (cal on)
dB
MHz
M1: -22.62 dB @ 806.2 MHz M2: -18.71 dB @ 902.3 MHz
baseline data
problem?
Negligible Change Here
FDR finds connector problems before water
intrusion destroys the cable.
Test Examples
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M1 M2
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
800 850 900 950 1000 1050 1100 1150 1200
Return Loss - with dent800 - 1200 MHz (cal on)
dB
MHz
M1: -17.20 dB @ 806.2 MHz M2: -17.86 dB @ 902.3 MHz
M1 M2
-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
50 100
Distance to Fault0 - 140 feet (frequency = 800 - 1200 MHz)
ReturnLoss(dB)
Feet
M1: -24.77 dB @ 14.1 feet M2: -36.91 dB @ 30.38 feet
Cable Defect, Dent
Antenna System with dent in cable
baseline data
problem?
Negligible Change Here
Test Examples
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M1 M2
-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
50 100
Distance to Fault0 - 140 feet (frequency = 800 - 1200 MHz)
ReturnLoss(dB)
Feet
M1: -37.83 dB @ 30.38 feet M2: -11.30 dB @ 112.86 feet
M1 M2
-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
800 850 900 950 1000 1050 1100 1150 1200
Return Loss - water in antenna800 - 1200 MHz (cal on)
dB
MHz
M1: -20.92 dB @ 806.2 MHz M2: -17.46 dB @ 902.3 MHz
Water in Antenna
Water can be hard to find in some antennas
Slight Changes Here
No Changes Here
Test Examples
W t i A t
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M1 M2
-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
50 100
Distance to Fault0 - 140 feet (frquency = 806 - 901 MHz)
ReturnLoss(dB)
Feet
M1: -25.35 dB @ 14.1 feet M2: -23.78 dB @ 115.03 feet
M1 M2
Del M1-M2: .99 dB, 95.0 MHz
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
810 820 830 840 850 860 870 880 890 900
Return Loss - water in antenna806 - 901 MHz (cal on)
dB
MHz
M1: -19.33 dB @ 806.0 MHz M2: -18.34 dB @ 901.0 MHz
Water in Antenna
Sweep only the antenna bandwidth
Slight Changes Here
problem?
baseline dataproblem?
Test Examples
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M1 M2
Del M1-M2: 2.67 dB, 99.2 MHz
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
800 850 900 950 1000 1050 1100 1150 1200
Return Loss - antenna moved800 - 1200 MHz (cal on)
dB
MHz
M1: -12.62 dB @ 803.1 MHz M2: -15.29 dB @ 902.3 MHz
M1 M2
-70
-60
-50
-40
-30
-20
-10
50 100
Distance to Fault0 - 140 feet (frequency = 800 - 1200 MHz)
ReturnLoss(dB)
Feet
M1: -24.55 dB @ 14.1 feet M2: -8.09 dB @ 112.86 feet
Storm Damage
High winds can mis-position the antenna
baseline data
problem?
Changes Here Also
Test Examples
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Introduction to Trace Interpretation A Trace is the measurement that results from a Line Sweep.
A Line Sweep measures the quality of an antenna or coax cable (acable plus antenna is called a system).
Traces (Line Sweep measurements) must be interpretedto determineif they Pass or Fail.
Traces are initially stored in the Anritsu Site Master instrument at theantenna site where they are made.
Later, Traces are transferred to a computer for interpretation.
Traces may be sent via CDROM, Memory Stick or email.
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Step 1: Check the bottom
Step 2:
CheckLeftSide
Step 3: Check Limit Line & Markers
Step 4:Check
theTrace
There is a 4 step process to interpreting traces:
6-4
Trace Interpretation
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Trace Interpretation ChartTypical Measurement Ranges
Insertion Loss Open or Short
System/Antenna
Antenna
Return Loss ofCable with Load
30
40
0dB
10
15
20
60dBFreq (MHz) Meters / Feet
Connectors
Coax/Load
0dB
5
15
25
Freq RL Mode DTF Mode
Less
More
Reflections
Load after Calibration42
If your Trace has
FREQ
along the bottom,use the left side of
this chart
6-6
If your Trace hasFEET or METERS
along the bottom,use the right side of
this chart
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Freq-Return Loss Measurement with a 50 ohm Load
6-13
-60
-50
-40
-30
-20
-10
1850 1875 1900 1925 1950 1975 2000 2025 2050
Limit : -33.5
Model: MT8212E Serial #: 01007099Date: 09/03/2010 Time: 02:50:16Std: --- Channel: N/AResolution: 259 FlexCAL:ON(COAX) CW: OFF
dB
Frequency (1828.0 - 2050.0 MHz)
Trace Interpretation - Basic Measurements
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Freq-Return Loss measurement with a 50 ohm Load
6-15
Trace Interpretation - Basic Measurements
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Freq-Return Loss of a transmission line and antenna
6-17
-60
-50
-40
-30
-20
-10
1850 1875 1900 1925 1950 1975 2000 2025 2050
Limit : -15.0
Model: MT8212E Serial #: 01007099Date: 09/03/2010 Time: 02:46:53Std: --- Channel: N/AResolution: 259 FlexCAL:ON(COAX) CW: OFF
dB
Frequency (1828.0 - 2050.0 MHz)
Trace Interpretation - Basic Measurements
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Freq-Return Loss of an Antenna
6-21
-60
-50
-40
-30
-20
-10
0
1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200
Limit : -15.0
M1 M2M3
Model: MT8212E Serial #: 01007099Date: 09/03/2010 Time: 02:59:37Std: --- Channel: N/AResolution: 259 FlexCAL:ON(COAX) CW: OFF
dB
Frequency (1700.0 - 2200.0 MHz)
M1: -15.01 dB @ 1844.161 MHz M2: -15.27 dB @ 2081.387 MHz M3: -25.98 dB @ 1913.504 MHz
Operating Range of Antenna
Best Operating Frequency
Trace Interpretation - Basic Measurements
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Antenna Sweep in Freq-SWR Mode
6-23
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
3.25
1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200
Limit : 1.42
M1 M2M3
Model: MT8212E Serial #: 01007099Date: 09/03/2010 Time: 03:01:16Std: --- Channel: N/AResolution: 259 FlexCAL:ON(COAX) CW: OFF
VSWR
Frequency (1700.0 - 2200.0 MHz)
M1: 1.439 @ 1844.161 MHz M2: 1.419 @ 2081.387 MHz M3: 1.104 @ 1913.504 MHz
Operating Range of Antenna
Best Operating Frequency
Trace Interpretation - Basic Measurements
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Insertion Loss of a transmission line with a short (Freq-RL Mode)
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1850 1875 1900 1925 1950 1975 2000
M1 M2
B-1 TX1RX1/ RTL SHORT
GSM 1900
Date: 06/28/2005 Time: 16:50:14
Resolution: 259 CAL:ON(COAX) CW: OFF
dB
Frequency (1840.0 - 2000.0 MHz)
M1: -6.15 dB @ 1862.90 MHz M2: -7.79 dB @ 1942.90 MHz
Marker to Peak-6.15dB
Marker to Valley-7.79dB
6-25
Trace Interpretation - Basic Measurements
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Insertion Loss of a transmission line with a short
Marker to Peak-0.70dB
Marker to Valley-0.92dB
6-27
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
800 810 820 830 840 850 860 870 880 890 900
M1 M2
Cable LossCABLE1CL
Date: 09/20/2005 Time: 18:23:16 Avg.CableLoss: -.81 dBResolution: 259 FlexCAL:ON(COAX) CW: OFF
d
B
Frequency (800.0 - 900.0 MHz)
M1: -.70 dB @ 826.40 MHz M2: -.92 dB @ 842.60 MHz
Trace Interpretation - Basic Measurements
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Distance to Fault - Return Loss Mode
6-29
Trace Interpretation - Basic Measurements
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Distance to Fault - SWR Mode
6-31
Trace Interpretation - Basic Measurements
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DTF-SWR of cable system DTF-RL of cable system
1.000
1.025
1.050
1.075
1.100
0 10 20 30 40 50 60 70
Limit : 1.07
M1M2M3 M4
Distance-to-faultSWR Mode Feet
Model: S332B Serial #: 00937026 Prop.Vel:0.880Date: 03/26/2002 Time: 08:57:55 Ins.Loss:0.013dB/ft
Resolution: 259 CAL: ON(COAX)
VSWR
Distance (0.0 - 70.0 Feet)
M1: 1.02 @ 56.43 ft M2: 1.04 @ 48.02 ft M3: 1.04 @ 8.41 ft M4: 1.11 @ 28.22 ft
-50
-40
-30
-20
-10
0
0 10 20 30 40 50 60 70
Limit : -30.0
M1M2M3 M4
Distance-to-faultRL Mode Feet
Model: S332B Serial #: 00937026 Prop.Vel:0.880Date: Mar/26/200 Time: 08:55:39 Ins.Loss:0.013dB/ft
Resolution: 259 CAL: ON(COAX)
dB
Distance (0.0 - 70.0 Feet)
M1: -40.92 dB @ 56.43 ft M2: -33.56 dB @ 48.02 ft M3: -33.56 dB @ 8.41 ft M4: -26.02 dB @ 28.22 ft
6-33
Trace Interpretation - Basic Measurements
T I i B i M
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DTF - End of transmission line terminated with an open orshort
-50
-40
-30
-20
-10
0
0 25 50 75 100 125 150 175 200
Limit : -30.0
M1 M2
Clifton Springs / 300R176ABlue 1 DTF Short
Resolution: 517 CAL: ON(COAX)
dB
Distance (0.0 - 220.0 Feet)
M1: -30.75 dB @ 0.0 Feet M2: -1.84 dB @ 209.34 Feet
End of transmission line
Ripple pattern caused by short(Miller Effect)
Notice this peak
6-35
Trace Interpretation - Basic Measurements
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T I t t ti B i M t
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DTF - End of transmission line terminated with a 50 Ohm load - FAILURE
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
0 10 20 30 40 50 60 70
Limit : -19.30
M1
Distance-to-faultDTF TERM
Resolution: 130 CAL: ON(COAX) CW On
ReturnLoss(dB)
Distance (0.0 - 76.0 Feet)
M1: -37.077 dB @ 68.341 Feet
Last connector
Connectors at main feedand top jumper
First connector
Fault in line
Notice the Marker
6-39
Trace Interpretation - Basic Measurements
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Trace Interpretation Basic Measurements
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Handheld Software Tools Trace Overlay of DTFtraces before and after setting Vp(Propagation Velocity)
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
0 10 20 30 40 50 60 70
Limit : 0.00
M1
Distance-to-faultDTF OPEN
Resolution: 130 CAL: ON(COAX) CW On
ReturnLoss(dB)
Distance (0.0 - 76.0 Feet)
M1: -2.418 dB @ 68.341 Feet
Before Correct Cable Type EnteredEnd of cable shown at 62 feet
With Correct Cable Type EnteredEnd of cable shown at 68 feet
6-43
Trace Interpretation - Basic Measurements
Master Software Tools
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Cable Analysis Products Overview
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Cable Analysis Products Overview
1-port 1-port, SPA,2-port transmission1-port,2-port transmission
S331E2 MHz to 4 GHz
S361E2 MHz to 6 GHz
S332E / Op212 MHz - 4 GHz VNA
100 kHz - 4 GHz SPA
S362E / Op212 MHz - 6 GHz VNA
100 kHz - 6 GHz SPA
S331E / Op212 MHz - 4 GHz
S361E / Op212 MHz - 6 GHz
VNA,1/2-port transmission
MS20X4A/B500 kHz 4 GHz
MS20X6A/B500 kHz - 6 GHz
1-port, SPA
2-port transmissionDemod, backhaul
MT8212E4 GHz VNA/SPADemod, Backhaul
Site Master VNA Master Cell/BTS
Master
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