Mike Underhill G3LHZ had some good ideas but his ideas that the theoretical loop equations were not valid were totally wrong. When I was active on 136kHz some years ago I used a large vertical loop and got reasonable results - in a QTH where I was severely restricted in what I could use on those frequencies. At one time I more or less proved to myself that the loop was performing pretty much how the theory predicted and G3LHZ's suggestions that it should be 100 times better (or whatever) were complete rubbish. You can find more information on the 136kHz pages on my website, with calculations on both the traditional loop equations and G3LHZ's (very old pages, not updated for yonks, but for some reason still seem the most visited pages on the whole site...).
73 Dave G3YMC On 4 Aug 2009 at 21:57, d.cut...@ntlworld.com wrote: > I went to one of those lectures by Prof Mike Underhill (G3L??) in front > of his IEE peers who did not receive his wisdom too readily. It seemed > like a one-man campaign. In essence he postulated that a mag loop was > more like a short folded dipole and he showed why. The usual calculated > losses were insufficient to show why loops worked the way they did. > > I once made a loop from 12ft x 4ft sheet aluminium with a huge capacitor > 4ft x 6inch vanes spot welded to the ends (that was an education in > itself). It was incredibly impractical, but I did it anyway. I > measured a 46dB front to side attenuation. I scrapped it soon > afterward. > > David > G3UNA http://www.davesergeant.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
