![]() ![]() Some purists do mount these things upside down on a tower side bracket when the antenna site is much much higher than the surrounding users of the radio system. The 3 dB beamwidth in the vertical E-plane is still quite enormous with energy both above and below the level of the antenna. ![]() This seems to cause the slight uptilt you most often see in ground-plane antenna documentation. This introduces one or more additional conductors below the radials that demonstrably (via simulation and measurement) draw/induce some power from the radials and flow energy below the antenna. Unfortunately we must mount the antenna and feed it with a feedline. ![]() Also for consideration, height above ground can be assumed to be in the 5 meter range.Īn elevated "ground-plane" antenna with tuned radials has, by itself, a pattern much like a dipole doughnut shape (freespace is what I'm talking about at the moment). I'm looking for more specific reasoning.Īnd in case it matters much for this answer, I am mainly considering the 2m range of frequencies. Searching the internet resulted in many variations of "Try it." or "It worked for me back in. My trials at modeling this with EZNEC resulted in no change based on the antenna's orientation, but I don't trust myself.Īlso, looking at just the plots would lead you to believe that there is zero chance of receiving a signal from below the antenna's elevations. antenna on a hill/mountain), would mounting the antenna upside down make any difference?Ī naive response would be that the antenna's pattern would be unaffected except to be rotated 180 degrees, i.e.:Īn answer to a similar question seems to imply that the radials on a ground plane antenna don't have as much to do with the pattern as the actual earth. Image from a similar question and see watermark.įor a situation where the signals of interest are below the antenna in elevation (e.g. A typical gain pattern for a quarter wave ground plane antenna is: ![]()
0 Comments
Leave a Reply. |