[Fwd: LF: Re: AMRAD Antenna ?]
Sat, 08 Jan 2000 16:33:05 -0500
> Hello All.
> Your comment about your antenna maybe operating like a LOOP is probably correct.
> I would suggest it is performing like a grounded quad. Similar systems used on 160
> and 80 metres where one cannot get a full size quad up.
> At 1600 ft long and 50 ft high, think that is what you said, its natural resonant
> frequency used as a grounded quad would be 296 khz. I expect there is some sort of
> loading to resonate on 137 khz.
> It would be interesting to check whether it radiates better as a loop or a long wire
> with the grounded far end disconnected. Judging by experiments in the past using
> loops v verticlals, I think the vertical/long wire approach would be better for low
> I have tried a variety of loops in the past for 160 metres ie 40 m loop resonated on
> 160 and although it was quieter than my full size quarter wave on 160, it was not as
> sensitive and did not pull in the long haul low angle dx, in fact there were signals
> that I could not hear that I was able to copy solid on the vertical, although at
> times probably noiser. Small loops for short/medium distances of several hundred
> miles are acceptable but for low angle long haul poor on mf/hf.
> A full size loop ie quad or delta etc resonant at the operating frequency and
> preferably at least a quarter wave above ground is a totally different story.
> In the UK stations using loops have poor signals compared to those using verticals,
> even low verticals heights with top loading. A couple of stations that have been
> using loops have changed over to verticals and although not very high made a hugh
> difference to their signals received at my qth.
> The so called long wire, just a few feet above ground and fed with a drop wire is
> really a top loaded vertical or inv L.
> The above comments are a result of experiments and observations, especially on 137
> khz and 1800 khz bands
> 73 de Mal/G3KEV