A vertical dipole can be balanced with the lower element shorter. It will have more capacitance to ground, which makes it electrically longer. This is like putting a capacitance hat on the end of an element.
wunder K6WRU On May 18, 2013, at 11:36 PM, Oliver Johns wrote: > ELEVATED RADIALS: I think Joe hits it on the head here. A vertical with > elevated "radials" is essentially an OCF dipole. There is no particular > reason for the "radials" to be a quarter wavelength. They should be whatever > length lets you resonate the antenna with a feed impedance you can live with. > > IMPT POINT: If you want your antenna actually to have a vertical radiation > pattern (low angle, omni-directional) then the elevated radials must be > symmetric. If there are two, they must be of exactly equal length and point > in exactly opposite directions. If there are four, they must be equal and > point in directions 90 degrees from one another. This symmetry guarantees > that the "radials" do not radiate. The do carry currents, they do help > resonate the antenna, but if they are symmetric radiation from them cancels > and they therefore do not radiate appreciably. > > 73, > > Oliver > W6ODJ > > > On 18 Jan. 2013, at 06:46 AM, "Joe Subich, W4TV" <li...@subich.com> wrote: > >> >>> Personally, I do wonder about the new fangled "no radials required" >>> antennas. But, I have an old R5 and it works well. >> >> The "no radials" antennas are basically a vertical OCF - the short >> decoupling radials are the short leg and the vertical is adjusted >> through the use of traps, stubs and/or loading to resonate on the >> desired band with the fixed length (typically 42") of the short >> "radials". >> >> 73, >> >> ... Joe, W4TV >> >> >> On 5/18/2013 9:25 AM, Bill wrote: >>> The cleanest installation is to put the radials in the ground - but, not >>> portable at all. The idea is a capacitance connection with the earth. I >>> have used welded steel cattle fence in the past - I build a mat that is >>> about 30 or 40 feet out from the base of the antenna. >>> >>> For raised radials - they must be resonate to function properly. Three >>> or four per band or related band. They have to be high enough that they >>> present no danger to anyone roaming around your antenna field. They can >>> be drooping or horizontal - both work well. >>> >>> Personally, I do wonder about the new fangled "no radials required" >>> antennas. But, I have an old R5 and it works well. Perhaps the way to go >>> is a new antenna that just gets bolted to a post and a feedline >>> attached. Sure makes life easier and from folks I talk to all the time - >>> they do work. Forget that they are a little expensive. You buy an >>> antenna to use for years. >>> >>> Read the eHam reviews and see what other users are saying before you buy >>> anything. Ask on the air. >>> >>> The best I ever had was a Butternut of some kind over a bunch of buried >>> fence. Might still be the way to go. But, if I was doing it now, I'd be >>> looking at a "no radials required" antenna. My reasoning is somewhat age >>> related. >>> >>> Be looking forward to the sage advice that will come from this post. It >>> is summer - so it is antenna time. >>> >>> Bill W2BLC >>> ______________________________________________________________ >>> 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 >>> >> ______________________________________________________________ >> 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 >> > > ______________________________________________________________ > 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 -- Walter Underwood wun...@wunderwood.org ______________________________________________________________ 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
