Building and Testing UTP LAN Cables to Insertion Loss Specifications
1000BASE-T/100BASE-TX/10BASE-T Physical Layer Compliance Tests Manual
116
Intel Confidential
Figure E-1. Network Analyzer Setups for Calibration and Measurement of Insertion
Loss
6. Turn correction on.
7. Set triggering to continuous sweep.
8. Put a marker on 16 MHz.
9. After calibration, check the calibration quality by measuring the two calibration standards.
a. Reconnect the short CAT5 through cable between the two baluns. Insertion loss should
be zero dB. Most network analyzers should be capable of zero dB /- 0.05 dB or
less.
b. Put the 100 ohm resistor loads back on each balun. The insertion loss (isolation) should be
greater than 40 dB (On many network analyzers, isolation will be > 60 dB).
Note:
Treat all loss and isolation levels as absolute values. If your analyzer displays an isolation/insertion
loss of -65 dB, it is actually 65 dB, unless you are measuring an amplifier or a device with greater
than unity gain (i.e. negative loss = gain).
E.1.2
Measuring the Insertion Loss of the Twisted Pair Cable
10. Connect a known length (preferably 50 meters or more) of the twisted pair cable between the
two baluns’ 100 ohm sides (Connect the network analyzer to the cable's TX pair: orange &
orange/white at both ends).
11. Record the insertion loss value for the marker at 16 MHz. The analyzer in should be in
continuous sweep mode.
12. Recalibrate if required, and measure the cable's RX insertion loss (green & green/white).
50 ohmtermination
on unused balun
50 ohmtermination
on unused balun
Balun Test Fixture
100
50
ohms ohms
100
50
ohms ohms
RJ-45
RX
TX
Balun Test Fixture
50
100
ohms ohms
RJ-45
50
100
ohms ohms
TX
RX
50 ohm
BNC cable
Network Analyzer
S-Parameter Test Set
or
Trans/Refl Test Set
50 ohm
BNC cable
