MICROWAVE
UPDATE 2004
page
four
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UPDATE
ACTIVITIES - TEST
GEAR
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Microwave
Update is a great place to get your newly built microwave masterpiece
thoroughly tested. This year was no exception and was helped
by the fact that one of the event's organizers Al Ward, W5LUA,
has strong connections with a very well known company that produces
high class test equipment! As a result there was a spectrum
analyser available to at least 24GHz and state-of-the-art noise
figure measuring gear.
This photo
shows one of the test benches being set up on the Thursday.
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Paul
Drexler, W2PED, shown here on the
right, was kept very busy measuring noise figures.
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Al
Ward, W5LUA, manned the Spectrum Analyser.
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Dave
Robinson, WW2R (and also G4FRE) spent
a lot of his time checking out various oscillators brought to
him for phase noise measurements.
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Meanwhile,
out in the rear carpark, Kent Britain, WA5VJB, had set
up his now famous travelling antenna test range. At the receiving
end of the range (left) you can see Sam, G4DDK, lending
a hand in the initial setting up of the test range.
This system uses a low power, AM modulated, RF
source at the far end of the range. A standard gain antenna is
used there and the receive end measures the signal level with
another standard gain antenna (eg a horn) so as to calibrate the
VSWR indicator that is used to measure the antennas under test.
The Antenna Under Test is then substituted
at the receive end of the range and the difference in dB is measured
between it and the standard. The measurements are done at AUDIO.
The short length of the range and the low height of the antennas
is deliberate and takes advantage of ground reflection. The absolute
gain of the A.U.T is calculated by adding the difference
measured to the gain of the receive standard gain antenna, as
shown on an HP VSWR indicator. |
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Here's the
Test Range transmitter end with the various sources set up on
or just above the ground.
The test range
has been used all over the USA and at the Martlesham Microwave
Round Table in the UK, with consistent and repeatable results.
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