Hi Martin,
I used the standard Europa Dipole in the tail and achieved SWR of 1.25 at the
lower
frequency, 1.11 mid frequency and 1.51 at top. This simply involved cutting
bits off the copper strip until the best reading was obtained.
Regards
Brian Davies
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Martin Tuck
Sent: 26 January 2020 23:29
Subject: Europa-List: Comm Antennas
So I was able to borrow a MFJ-259 tester and hooked up my old 'monopole'
VHF antenna to measure the resonant frequency of the antenna and the
SWR. The resonant frequency is the point at which you get the lowest SWR
on the meter.
I found the resonant frequency at 116.4 but still had a SWR of 2.4
(ideally you want it close to 1) so this is high.
At our typical frequencies between 118.0 mhz and 138 mhz, SWR ranged
between 2.7 and 3.6. I thought this rather disappointing although it
might explain why my transmissions at the upper end (134.80) to ATC are
rather difficult for them to hear.
I did hook up a Bob Archer antenna which is a dipole and appears pretty
simple with no apparent scope for adjustment. I was surprised to get a
resonant frequency at 109.5 mhz with a SWR close to 1. At 118.0 SWR was
5.8 and at 138 mhz it was 6.5! I don't think it is going to work with
readings like that.
I guess the question is, what comm antennas have others used that have
been found to be successful? I'm particularly interested to know the
best way of providing a suitable ground.
Regards,
Martin Tuck
Europa N152MT
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