I agree. I would just add that if you use an inverted L or V configuration, be sure the included angle is 90 degrees or greater. Otherwise there will be some cancellation of radiation from the two legs. As a thought experiment, consider what would happen if you reduced the angle to 0. That would make the antenna into a parallel line which wouldn't radiate at all.
Vic, k2vco > On Sep 23, 2014, at 2:20 AM, Rick Dettinger <[email protected]> wrote: > > I have a similar antenna. > I would use the inverted "V" or "L" configuration. You want the center of > the antenna as high as possible. > Mine is an inverted "L", but the far end actually is about 20 feet below the > center, which is 50 feet high. The maximum radiation is where the current is > greatest, a quarter wave from the far end, which has no current. Mine works > quite well for a single wire. I made it a little more than a half wave at > the lowest frequency, so I can use a remote tuner at the base for other > bands. I feed it against a less than great radial system for all bands, but > for a half wave, this might not be very important. The base is 140 feet from > my shack, fed with coax in a conduit. I also have a 43 foot vertical, which > I can select by remote switch. Except on 20 M, the inverted "L" usually > works better. > > 73, > Rick K7MW > > > > > >> On Sep 22, 2014, at 2:49 PM, <[email protected]> wrote: >> >> Hi All, >> >> Here's a question for the antenna gurus among the group. It's about the >> best way to deploy an end fed half wave antenna. >> >> First of all, I assume most would say to put the entire antenna up in the >> air as high as possible, and in a horizontal plane. I understand the >> advantage of doing that. However, what about a situation where you only >> have one support? My first inclination would be to deploy the antenna like >> a sloper, with the far end at the top of the support, and the other end at, >> or near, the rig. I started wondering, though, about where the maximum >> radiation occurs. In a half wave antenna, the current max is more or less >> in the center of the antenna. So, would it be better to get the center of >> the antenna as high as possible (taking advantage of the one support you >> might have), and then maybe bending the other half back downwards, sort of >> in inverted vee fashion? That would be as opposed to just running the >> antenna up in a straight line to the top of the support, thus possibly only >> getting the center about half as high as the top of the support. >> >> Here's a more definitive description of what I am thinking about, and >> compares to the situation I have. I have a pole that goes up approx. 40 >> feet. If I deploy the EFHW in sloper fashion, with one end near the ground >> close to the rig, the center of the antenna would only be at approx. 20 >> feet. Also, On 40 meters (the band I would be using), the pole would need >> to be some 50+ feet from the rig. Alternatively, what if I move the center >> of the antenna up closer to the top of the pole, and have the rest of the >> antenna slope back down to another tie point? Wouldn't this be apt to work >> better, even though I have created something similar to an inverted vee? >> >> I know a couple of RVer's who do something similar. They have two poles in >> use, one of which is much taller. They deploy their antenna so that the mid >> point of the antenna is near the top of the tallest pole, then over to >> another shorter pole, and then back down that 2nd pole vertically--almost a >> somewhat slanted "U" shape. Their results seem to be decent, but I don't >> know if there is a better way to do it. Their method condenses the lateral >> space required to deploy the antenna, thus fitting within most RV sites. I >> don't know exactly what this does to the impedance at the feed point, but >> they use tuners to resolve any mismatch. The pole I have is somewhat taller >> than either of the ones they use. >> >> Anyway, I assume I could do the sloper approach without creating any serious >> issues, but I'm curious about what others think of the "vee" approach to get >> the antenna center higher. >> >> I appreciate any suggestions. >> >> Dave W7AQK >> >> >> ______________________________________________________________ >> 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]
