And, if you don't have enough space for a radial field on the ground, try a vertical doublet, center fed with balanced line for multi-band operation. I've been using one for years which is 32 ft. tall and can be loaded easily from 30 meters to 15 meters. Much better for dx than my low dipole and the elevated feedpoint (at 16 ft.) seems to help overcome ground clutter (enclosing block walls etc.). The wire is supported by a 32 ft. telescoping fiberglass pole, with footprint less than one square foot!
Bob NW8L On Mon, Dec 14, 2009 at 12:58 PM, Ron D'Eau Claire <r...@cobi.biz> wrote: > As Ken mentioned, height is an important factor in a horizontal or > semi-horizontal antenna. There's limited "gain" in any direction at low > angles unless the radiator is 1/2 wavelength above ground. That's why most > of us have to live with little directivity on the lower bands. > > The option is to consider verticals. Unless you are living on salt water (or > atop a sheet of copper), or can make the vertical a full 1/2 wave high, the > vertical won't be as efficient as doublet or dipole, but a vertical will > produce typically much better signals at lower angles of radiation than a > horizontal antenna (under 1/2 wave high) and doesn't require a huge > 'footprint'. Also you can phase multiple verticals for directivity and even > design them so you can use them for supports for horizontal wires on the > higher bands. > > You've probably noticed that 45 foot verticals are being heavily promoted > these days. That's an old design that is very handy for limited space. It > provides low angles of radiation on all bands up through 20 meters where > it's 5/8 wavelength high (on bands where it's more than 5/8 wavelength the > angle of the main lobe rises from the horizontal and minor lobes appear at > high angles). Down on 80 meters it's just a bit shy of 1/4 wavelength. With > a good ground system it can produce excellent results down there and even on > 160 - especially when compared with the short, low (in wavelengths above > ground) antennas most of us are forced to use on those bands > > Ron AC7AC ______________________________________________________________ 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
