N4KG comments interspersed in text.
On Thu, 14 Aug 1997 15:45:49 +0100 Peter Chadwick
<Peter.Chadwick@gpsemi.com> writes:
>Greg asks:
>
>>Maybe I've missed something, but I don't understand why everyone is
>>so keen to achieve an exact resonance. What is so difficult about
>>tuning out the reactive part?
>
>History says an antenna must be resonant.
LORD NO!
One of my favorite antennas is a simple 20M (halfwave) dipole
which I use primarily on the WARC bands but is tunable from 10 to 30 M
(using ladderline feeders) and a Johnson 250 W (AM full carrier) tuner
which
handles 1KW CW/SSB with no arcing or melting. In my early days on the
WARC bands, I convinced an African station to work me on 12 and 17M
using his 15M co-ax fed dipole. He was so excited he asked if I thought
it would work on 30M. It did, and he stayed for a full hour, handing out
the
first 30M contacts ever from his country.
Bottom line: an antenna need NOT be resonant to radiate. de Tom N4KG
(Transmission line losses are reasonably low for SWR below 3:1 on the
high bands, higher on the low bands).
I've never seen a reason for
>it either, but there are experts around who claim that if an 80m
>dipole
>is more than 10KHz off resonance, it won't work - or at least won't
>work
>DX.
>
I tune my 80M antennas for CW and use a tuner (MN-2000) on SSB.
With 310 countries on 80M, I would say that they work. de N4KG
>It's also been claimed by the same experts that lowest SWR is always
>achieved at resonance for any antenna.
Not necessarily. Look at the impedances on a Smith Chart. de N4KG
I trust generalisations less
>and
>less as I get older
>
>73
>
>Peter G3RZP
>
>--
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