[hpsdr] Proposal for Loop Antenna Project

[Robert M. Ganter HB9DNN]

Hi Ulrich, hello list,

> I have such a magnetic loop antenna at my QTH (DL1R) in Munich and a
> 10 m military  ship board whip antenna with an antenna tuner, both
> operating at 150 Watt.
> The whip antenna has always outperformed the loop antenna, which only
> covers a 1:2 freq. range.
Question here might be: outperformed where, at RX or TX?
> The loop antenna requires frequent mechanical retuning for 5 to 10
> KHz, that keeps you always busy .
This is both a disadvantage and an advantage. Disadvantage because it
keeps You busy tuning the antenna, *tremendous* advantage, howewer,
because such an extremely small bandwidth antenna is an excellent
preselector.
I agree with Ulrich that magnetic loops are not the best idea for
transmitting (very low efficiency). For RX SNR is much more important
and this is where the loop antenna (maybe even with a preamplifier)
outperforms broadband antennas. Apart from that a small variable air
capacitor (or maybe relay switched caps?) can be used because no high
voltages will build up as is the case even with QRP TX power levels. If
the switched cap solution works this would even solve the "busy
disadvantage".

For TX I think even a relatively short wire antenna plus antenna tuner
will do a better job than a loop antenna.

73 Robert HB9DNN

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