This is not the case with vertical HF antennas. Nearby ground only contributes loss. This even more so when the ground forms part of the return path of the radiating structure. Even when far-away ground reflections may cause the directivity of a vertical HF antenna at low take-off angles to be much higher than that of a horizontal HF antenna, its net gain will still be lower at those angles. This makes the horizontal HF antenna a clear winner, at least for what transmission is concerned. Note that gain and directivity are not synonyms; gain takes into account losses, directivity does not.
Vertical HF antennas do have their merit though. At the lower end of the HF spectrum, the λ/2 height requirement for horizontal antennas can become cumbersome (even though a horizontal phased array may weaken this requirement by allowing somewhat lower heights). A vertical HF antenna can get away with a height of only λ/4. Furthermore, the directivity of a vertical HF antenna can be effectively employed at the reception end to cancel out high-angle interference by near-by stations. This is why some stations use receive-only phased-arrays of verticals on the low bands.
At a height of about λ/2, the nearby ground reflection of a horizontal HF antenna will start to be constructive at interesting take-off angles for long- distance ionospheric contacts. This will provide a net gain over the antenna in free-space.
If you can have only one antenna and can chose between a vertical HF antenna or a relatively high horizontal HF antenna, go for the horizontal antenna.
|RE: DX Antennas: Verticals vs. Horizontal:|
|by N4UFO on November 25, 2013||Mail this to a friend!|
N4JTE, I just looked at your QRZ page... did you try out those experiments in THAT back yard? With all those two story buildings that close all around??? And also mountains in the near distance?!!! PFFFT!!! No WONDER! That's simply NOT a fair comparison AT ALL. OF COURSE if you put a vertical down in a bowl, it will do WORSE than a dipole sitting ABOVE the bowl!
Please understand, I am not trying to rip you or start an argument, but you apparently started out with an agenda to disprove the idea that verticals are not as good as horizontal antennas... I will concede that point, PROVIDED that you accept the caveat/disclaimer... NOT IN YOUR BACK YARD.
To do otherwise is to be intellectually disingenuous and frankly downright absurd. Go move to a flat open piece of property somewhere and try the experiment again... you might change your mind. X^(