Measuring Electric Length Of Cable - Deepace KC901M User Manual

During the measurement, every measurement data can be saved by using the
combined key SHIFT+1 which is for further analysis. To be more user-friendly, KC901M
will name the files automatically and chronologically. Alternatively users can rename
the file as saving with the combined key SHIFT+3.
Before measuring the testing antenna gain, install the reference antenna (with
known gain) on the stand of the under-the-test antenna. Afterwards, adjust the
orientations of the reference antenna and the testing antenna to aim (make the
reference antenna aligns the under-the-test antenna according to the gain orientation
which is already given). Then do the user calibration in S21 mode and keep the setting
parameters of the instrument. Then replace the reference antenna with the
under-the-test antenna, and test and record the S -parameters in every different
angle. There derives the antenna gain in different angles by the summing up the
tested parameter and the gain of the reference antenna.
Repeat the steps above if you need to test the directivity diagrams and gains in
different frequencies.
Frequency can't be changed during the test, otherwise user calibration will be
useless and the data will also be invalid. Meanwhile the operator should keep a far
distance from the antenna especially when reading the meter .
When using two pc of KC901M, they can make a scalar network testing system of
single frequency point by setting one of KC901Ms in signal source and another one in
FIELD mode. This system can be used when the two antennas are miles away from
each other. One of the KC901M, which is used for emission, can also be replaced by a
transmitter that has a steady power level. Since the isolation in this way is better than
the internal insolation of a single instrument, it can satisfy some testing applications
which need a large dynamic range. Vice versa, if an operator needs a larger dynamic
range to do other S21 tests, he/she can use a PC to control two pc of KC901M at the
same time).
4.3 Measuring Electric Length of Transmission Line
When the transmission line's end is in open circuit or short circuit, user can use
KC901M to measure its electric length. In mode S11, adjust it into PHASE display and
take the part of the curve which is smooth and obviously periodical. Then measure
the frequency difference length (Δλ) after the phase rolled one circumference (the
difference between two cursors' frequencies is nearly 0°N) and divide it by 2 so as to
obtain the electric length of the transmission line. After it, you can get the electric
length of the transmission line. Of course, user can also measure the frequency
difference length after the phase shifts 180°N .Then divide it with 4 to get the result
directly, or try to get the result by measuring two frequency difference length after
two 360°N.
User can also save the data first and then get the group delay by getting the
derivation of the phase on PC to work out the electric length. In this case, user should
choose the smaller SPAN or many sweeping points to avoid phase aliasing.
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