Antenna problem solved

Alan Wilkie alan at
Mon Aug 13 08:40:59 EST 2001

Over the weekend we finally resolved the saga of trying to get our new
helical antennas working.  Thanks to the people who wrote to me with
suggestions, I thought for future reference you might be interested to
know what the problems were.

Several people suggested that cable attenuation might be a problem, so
we tried ever shorter pieces of cable until we got down to about 50cm,
and still got nothing even when the aerials were in the same room.  We
were using RG58 at that stage, and while its attenuation is high, we
still expected to get some kind of signal.  We also didn't have the
right connector for the back of the WL200 card (reverse thread SMA), so
we had the cable soldered directly onto the card.  It was definitely
soldered to the same pins that go out to the connector, but it seems
that the signal didn't like turning the corner.

When we got the pigtails with the proper connectors, the link sprang to
life.  The pigtails are also wired using low loss RG58, so it appears
that the connectors are an important part of the whole process.

Something else for future experimenters to note is that it seems that
having the antennas close to or on the ground is a bad thing.  In one
test we had the antennas just a few metres apart with perfect line of
sight, one elevated and one on the ground.  The connection was there,
but patchy and could be disrupted just by walking in front of the
antenna.  When we put the second aerial up on a pole, the signal was
apparently much stronger and much harder to disrupt.

Anyway we got our first association between the houses working yesterday
and all is well.



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