Your analysis agrees with my experience, Eric. The dipole arranged with one leg vertical and one leg horizontal can be very good for something like field day in which you want to work stations at all distances from "just down the street" to DX. That horizontal leg will produce very high angle radiation like any horizontal antenna at low height. Of course if it's very close to the ground much of the RF will be absorbed by the earth loss.
Verticals with a good "ground plane" or efficient ground often fail to produce well inside a range of several hundred miles, thanks to their lack of high angle lobes. That's okay for DX chasing but not so good for something like Field Day unless you're a thousand miles from anyone, Hi! Some shortening does have little impact on efficiency from the data I have. For example, one analysis I have shows that a center fed wire only 1/4 wave long, end to end, is only about 1.5 dB lower in gain than a full half-wave center fed wire. It's the tiny antennas that are mostly loading coil, like mobile whips for 80 or 160 meters, that really suffer, and it's amazing how well they can get out in spite of the huge penalty they pay having a lousy (read, "almost nonexistent") ground! They prove that only a few watts ERP will cover large distances under the right conditions. 73, Ron AC7AC -----Original Message----- Verticals can be very efficient with just one elevated radial. Of course, such an antenna can be viewed as a dipole, so yes, dipoles are good! Is it better to have one leg of the dipole horizontal at 8 ft or vertical? My experience is that on dry and rocky ground horizontal is usually better, but only by a little, and not by anything close to 30 dB. There are also big differences in performance depending on distance and skip angle etc, so the vertical can sometimes work better for an individual path. Where the ground is wet with salt water I believe the vertical configuration will win by a good margin (I have no personal experience though), and many real-life situations may fall somewhere in between. A good loading coil doesn't affect efficiency much as long as the antenna leg is shortened by less than 50%. On the upper bands it is rather easy to avoid loading coils altogether, either in homebrew configurations or using the extension rods offered by the commercial makers. However, if a horizontal dipole leg is shortened by a coil, it is still the same height. If a vertical is shortened, it will have less average height, giving it further disadvantage versus the horizontal, but again subject to great variations depending on the surroundings and propagation path. It doesn't hurt to have the capability to set up alternative configurations to find out what works best in a given situation. 73, Erik K7TV ______________________________________________________________ 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
