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 ---- Ron D'Eau Claire <r...@cobi.biz> wrote: > Clearly there's a lot of interest in small transmitting loop antennas, so > here are some links I've collected over the past several years that are > still good detailing the efforts of several Hams (I checked them to make > sure they still work ;-): > > Harry, SM0VPO, has several interesting designs including one built on a > "packing crate" about which he wrote: > > " I have been placed in a situation where a landlord denied permission to > erect an antenna. Any form of antenna was unreasonable, even a white-painted > broom handle caused interference!! My dartboard frame did not cause any > interference at all..." and so he evolved his novel and stealthy small loop > transmitting antenna. > > He also describes an 80 meter frame antenna. At the site below, click on > "Projects", then "Antennas" and then look at links under Antennas on the > left side of the page for "80 meter frame ant" and "Packing crate ant". > > http://web.telia.com/~u85920178/ > > -------------------------------------------------- > > David, PA3HBB/G0BZF has this nice page detailing his work with loops at: > > http://www.qsl.net/pa3hbb/magloop2.htm > > At the time he wrote the page he traveled a great deal and writes, " In > order to fill my evenings with something other than foreign television (or > drinking in the bar), I prefer to sit in my room and work the DX on the > radio. Though this situation may not be typical of all of radio amateurs, > the need for a small, effective and portable antenna will surely hit home > with a number of them." > > --------------------------- > > As a sign of the interest small transmitting loops generate, one fellow in > Belgium created a very nice page detailing his loops and the work of others > that ended up swamping him with e-mails, so it was relocated under a new > URL: > > http://www.qsl.net/mnqrp/Loop/Mag_Loops.htm > > It details making loops as well as ideas for making your own low-loss > capacitors to tune them with. > > ------------------------------- > > DJ3TZ built a small loop using copper tubing shown here: > > http://www.qsl.net/dj3tz/loop2.html > > It has a nice fairly self-explanatory photo but most of the links on that > page to other pages are now out of date. > > -------------------------------------- > > > 73, > > Ron AC7AC > ______________________________________________________________ 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
