Some people use 1/4 inch flexible copper tubing, the kind you use to hook up the icemaker on a refrigerator. You can hammer the ends flat, drill a hole, and connect them. It is about $1/foot and reasonably self-supporting.
This appnote at MFJ has some good information on DIY loops: http://www.mfjenterprises.com/antennatalk6.php wunder K6WRU On May 20, 2013, at 7:31 PM, Ron D'Eau Claire wrote: > As an alternative to copper pipe, you might consider copper foil. RF flows > along the surface of the conductor so it matters little how thick it is. You > might take something like PVC tubing, form it into the required loop, and > cover it with copper foil. Just be sure you use a single piece so you don't > have to "splice" it anywhere around the loop that would require the RF > currents to cross the splice. You might get away with a soldered seam > running all the way around the loop but I suspect the solder wouldn't do > anything. Just be sure the copper overlaps along the edge. Use tape or > ty-wraps to secure the copper. > > Next to the ohmic losses in the loop itself, the majority of losses in loops > is in the junctions connecting the loop to the capacitor and in the > capacitor itself if it has a sliding contact to the rotor. > > 73, Ron AC7AC > > -----Original Message----- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Vic K2VCO > Sent: Monday, May 20, 2013 7:07 PM > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] magnetic loop antennas > > I googled 'flexible conduit' and what I see looks like BX cable -- made out > of a single flat piece of metal wrapped in a spiral shape. If this is what > you are talking about, it would be AWFUL for this purpose -- it would have a > very high RF resistance and so be very inefficient. There are very high > currents in the loop and you have to keep the resistance at RF as low as > possible -- that's why large-diameter copper tubing is good. > > Do you have a link to a picture of the stuff you are looking at? > > On 5/20/2013 6:43 PM, Bill Blomgren wrote: >> I saw the great writeup on the magnetic loop antenna and the inventive >> High Voltage capacitor for tuning the thing. I'm looking at one of >> them strictly because I'm stuck in an apartment. >> >> The fact it should be good for 100 watts is perfect for what I'm looking > at buying. >> >> I'm just wondering about the copper pipe used for the outer loop... I >> spotted some very reasonably priced flexible conduit that could be >> used for the "loop" proper. Do what is necessary to bond the >> capacitor into the rig, and it would appear to be a reasonable >> alternative to the rather pricy copper pipe. (They want your first born > here for that, and the thieves are busy collecting anything that isn't > nailed down. >> >> Thoughts on that for its larger diameter, which should help with the >> coupling to the rest of the world... > > -- > Vic, K2VCO > Fresno CA > http://www.qsl.net/k2vco/ > ______________________________________________________________ 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
