That might fit. Maybe something a little shorter, say 18". Can it be used with just 2 feet of coax? What's the bandwidth? How does it compare to a 3' loop or a 4' whip?
Wayne N6KR > On Jan 23, 2019, at 9:51 AM, Jeff Wagner <[email protected]> wrote: > > See the picture of a 20 Meter EH antenna on my QRZ page > https://www.qrz.com/db/KK6CUG. > > It would fit into a backpack but it's 20 M only. Beer bottle for scale only - > hi hi. > > https://www.qrz.com/db/KK6CUG > > Jeff, KK6CUG > > On 1/23/2019 8:34, Wayne Burdick [email protected] [KX3] wrote: >> The entire purpose of the exercise is to be able to operate while walking. >> If the field is a potential health risk, power would have to be dropped >> accordingly. >> >> Wayne >> >> > On Jan 23, 2019, at 8:28 AM, Jim Miller <[email protected]> wrote: >> > >> > I assume that this "backpack frame antenna" wouldn't be actually used when >> > being worn. The circulating currents in a Hi-Q loop result in strong RF >> > fields along the loop axis which should be avoided in use. >> > >> > jim ab3cv >> > >> > > > > > > > > > > >> > On Wed, Jan 23, 2019 at 11:21 AM Wayne Burdick <[email protected]> wrote: >> > Wish I had time to build one of these myself! A few other things in the >> > queue.... >> > >> > Wayne >> > N6KR >> > >> > >> > > On Jan 23, 2019, at 6:32 AM, 'Dale Parfitt' [email protected] [KX3] >> > > <[email protected]> wrote: >> > > >> > > >> > > HI Wolf, >> > > >> > > VK3YE could have done so much better from an efficiency standpoint >> > > without making the loop any larger. >> > > >> > > 1. Flat metal stock is not as efficient as round stock (of the same >> > > circumference) because current crowding at the edges of the rectangular >> > > stock makes it appear smaller in surface area. >> > > >> > > 2. A much lower D capacitor such as a dual gang air variable with the >> > > gangs in series (to avoid resistive losses in the bearings) or a >> > > butterfly would also have aided in higher efficiency. >> > > >> > > 3. Copper would have helped efficiency somewhat with its lower RF >> > > resistance and ability to be soldered versus mechanical connections, but >> > > that is partially offset by aluminum’s larger skin depth. Of course >> > > copper is heavier and more expensive, but in tube form the weight issue >> > > could be minimized.. >> > > >> > > >> > > >> > > Just some thoughts. Again, the VK1OD calculator allows one to make >> > > precise efficiency measurements so even small improvements can be >> > > measured. As an example, the difference in efficiency between using >> > > braided coax as the loop radiator versus hardline or copper tubing is >> > > readily apparent. For the same diameter loop and same conductor >> > > diameter, a narrower bandwidth means higher efficiency. >> > > >> > > >> > > >> > > Dale W4OP >> > > >> > > >> > > >> > > From: [email protected] [mailto:[email protected]] On Behalf Of >> > > 'Wolf Hoeller, OE7FTJ' [email protected] [KX3] >> > > Sent: Wednesday, January 23, 2019 4:57 AM >> > > To: [email protected] >> > > Subject: Fwd: [KX3] Urban stealth HF: Inside-the-backpack loop antenna? >> > > >> > > >> > > >> > > >> > > >> > > Wayne, >> > > >> > > >> > > >> > > a really good idea. >> > > >> > > Have a look at VK3YE's youtube channel for his experiment to put a loop >> > > antenna in (frame of) a notebook bag. >> > > https://www.youtube.com/watch?v=BC5lFbLqaeg >> > > >> > > >> > > >> > > Another good idea for a stealth antenna has the spain company Inac. Here >> > > is the suitcase with a loop inside the frame: >> > > https://www.inac-radio.com/MAK721PRO >> > > >> > > >> > > >> > > I would like the idea, to sit in an urban park with my backpack or >> > > similar on my knees and make some contacts. >> > > >> > > >> > > >> > > >> > > Wolf, OE7FTJ >> > > >> > > Emergency Communications via Winlink Global Radio Email ®️ >> > > >> > > >> > > >> > > >> > > >> > > >> > > >> > > Am Di., 22. Jan. 2019 um 21:57 Uhr schrieb Wayne Burdick >> > > [email protected] [KX3] <[email protected]>: >> > > >> > >> >> > >> >> > >> I’ve engaged in plenty of ultralight HF pack operation, with a KX2, AX1 >> > >> antenna and a dragged counterpoise. In wide open spaces it’s a blast. >> > >> But urban settings with dogs, wire-eating cacti and overzealous >> > >> Neighborhood Watchers can distract from one’s radio experience. >> > >> >> > >> >> > >> >> > >> So, just for grins, I’d like to try something completely incognerdo: no >> > >> visible antenna. A small remotely tuned loop (say 12” diameter) would >> > >> seem to be the best choice, as it would fit entirely inside a small >> > >> backpack. It could have modest efficiency while not requiring a >> > >> counterpoise wire. Rigid 1” copper pipe formed in a square would be >> > >> convenient to deploy. >> > >> >> > >> >> > >> >> > >> The loop would be only 6 to 8” from soft tissue, so you’d want to run >> > >> QRP, of course. OTOH, we’re talking about HF. A cellphone by your ear >> > >> is probably worse. >> > >> >> > >> >> > >> >> > >> Any other antenna suggestions? >> > >> >> > >> >> > >> >> > >> Wayne >> > >> >> > >> N6KR >> > >> >> > >> >> > >> >> > >> >> > >> >> > > >> > > >> > > >> > >> > __________________________________________________________ >> > 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] >> >> >> __._,_.___ >> Posted by: Wayne Burdick <[email protected]> >> Reply via web post • Reply to sender • Reply to group >> • Start a New Topic • Messages in this topic (1) >> >> Have you tried the highest rated email app? >> With 4.5 stars in iTunes, the Yahoo Mail app is the highest rated email app >> on the market. What are you waiting for? Now you can access all your inboxes >> (Gmail, Outlook, AOL and more) in one place. Never delete an email again >> with 1000GB of free cloud storage. >> VISIT YOUR GROUP >> • Privacy • Unsubscribe • Terms of Use >> >> SPONSORED LINKS >> >> >> >> . >> >> >> __,_._,___ > -- > Jeff > ______________________________________________________________ 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]
