Distance-To-Fault (DTF) Transmission Line Test
The Distance-To-Fault transmission line test verifies the performance of the transmission
line assembly and its components and identifies the fault locations in the transmission line
system. This test determines the return loss value of each connector pair, cable component
and cable to identify the problem location. This test can be performed in the DTF–Return
Loss or DTF–SWR mode. Typically, for field applications, the DTF–Return Loss mode is
used. To perform this test, disconnect the antenna and connect the load at the end of the
transmission line.
Required Equipment
q
Site Master Model S331D/S332D
q
Precision Open/Short, Anritsu 22N50
or
Precision Open/Short/Load, Anritsu OSLN50LF
or
Anritsu InstaCal Module, ICN50
q
Precision Load, Anritsu SM/PL
q
Test Port Extension Cable, Anritsu 15NNF50-1.5C
q
Optional 510-90 Adapter, DC to 7.5 GHz, 50 ohm, 7/16(F)-N(M)
Device Under Test
q
Transmission Feed Line with Load
Procedure - Return Loss Mode
The following steps explain how to make a DTF measurement in return loss mode.
Step 1.
Press the
MODE
key.
Step 2.
Select
DTF-Return Loss
using the Up/Down arrow key and press
ENTER
.
Step 3.
Connect the Test Port Extension cable to the RF port and calibrate the Site Mas-
ter as described on page 3-2.
Step 4.
Save the calibration set up (page 3-14).
Step 5.
Connect the Device Under Test to the Site Master phase stable Test Port Exten-
sion cable. A trace will be displayed on the screen as long as the Site Master is
in sweep mode.
Step 6.
Press the
FREQ/DIST
key.
Step 7.
Set the
D1
and
D2
values. The Site Master default for D1 is zero.
Step 8.
Press the
DTF Aid
soft key and select the appropriate
Cable Type
to set the
correct propagation velocity and attenuation factor.
NOTE: Selecting the right propagation velocity, attenuation factor and distance
is very important for accurate measurements, otherwise the faults can not be
identified accurately.
Step 9.
Press
SAVE DISPLAY
(page 3-14) name the trace, and press
ENTER
.
Step 10.
Record the connector transitions.
4-6
Chapter 4 Cable & Antenna Measurements