With remembering that the transmission pattern of the 1/2 wave dipole is much
flatter
than a quarter whip. You will have much better reception at long range
.
Graham
> On 27 Jan 2020, at 17:37, Brian Davies <brian.davies@clara.co.uk> wrote:
>
>
> 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
> To: Europa Builders Forum
> 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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