I would agree with the portable lossy versions. Definitely not the properly constructed versions. The loop on the left is for transmitting, and is 2" diameter tubing. Yes, I have some weed removal due. :) Not all loops are created equal, with minimal resistive losses and a well designed capacitor/tuning mechanism they can be relatively efficient. This one is quite good on 20, and better on 40 than any traditional wire antenna I could setup with the yard and lack of trees. A halfwave dipole a halfwave up on 40m would outperform it by 4dB or so. No way I could get an antenna like that setup. The trade-off is of course being extremely high q, a very narrow bandwidth. Hence the RX loop on the right.
https://goo.gl/photos/PExWyEYZmtVQDSgf7 The downside is the weight and bulk, a small transmitting loop made out of some coax is going to be down on efficiency significantly, and even low wire antennas probably will outperform them. Sure are easier to setup when you don't have trees around, however. Just wanted to make sure people understand STLs are not necessarily low efficiency, just certain designs are, and the portable models I've seen all fall in that category. On Apr 21, 2017 22:02, "Ron D'Eau Claire" <[email protected]> wrote: > The very BEST magnetic loops are incredibly inefficient, yet like any > "incredibly inefficient" antenna one can make amazing contacts on them when > conditions are right. > > The problem is with resistive losses. The day we have room-temperature > superconductors, we will have efficient small transmitting loops. Until > then, only a few percent of the power applied is radiated. > > For now, they are great when simplicity of setup allows operation where > otherwise nothing could be done. > > 73, Ron AC7AC > > -----Original Message----- > From: Elecraft [mailto:[email protected]] On Behalf Of Phil > Hystad > Sent: Friday, April 21, 2017 7:45 PM > To: Eddy Avila > Cc: Elecraft > Subject: Re: [Elecraft] Experiences using a portable HF loop > > The May 2017 QST not only does a review of the Elecraft KX2 but it reviews > the Alpha Antenna, 10-40 meter support. This is a magnetic loop antenna > and > I think it retails (basic model) for $299. > > 73, phil, K7PEH > > > On Apr 21, 2017, at 6:24 PM, Eddy Avila <[email protected]> wrote: > > > > Greetings all, I'm curious to hear from anyone using a portable HF > magnetic loop. I've read the theory behind them so I'd like to hear your > opinion about them? How efficient these antennas are, especially running > qRP. > > > > > > Thanks all, > > > > > > 73 > > > > > > ed > > ______________________________________________________________ > > Elecraft mailing list > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:[email protected] > > > > This list hosted by: http://www.qsl.net Please help support this email > > list: http://www.qsl.net/donate.html Message delivered to > > [email protected] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message > delivered to [email protected] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
