Don’s Antenna talks by N4DJ

I have been studying low band(160, 80 and 40 meter) verticals and ground systems a long time. Some of the things I have concluded and info I have found is not exactly common knowledge among hams. Unfortunately there is much info out there that is not exactly correct and even more only half way correct. Let’s say there are a lot of “half truths” out there being passed around as correct. There is a large void in the knowledge of how grounds and radials for verticals work. It is complicated. All radials do not exactly work the same. From my point of view there are at least four types of radials (uninsulated buried, insulated buried, insulated on the ground, and above ground) They all do the same thing and that is collect ground or return currents. How they do it is sometimes slightly different and sometimes significantly different! Buried uninsulated radials and ground rods do it by being in contact with the ground. Thus the weak point is the size of contact area where the bare conduc...

  The graph above the graph above shows the gain that can be achieved by stacking dipole antennas. The gain depends primarily on the spacing between the dipoles. We should look at two such dipoles. If we do we see the maximum gain is about 4.5 dB over a single dipole and that occurs at about 3/4 wave spacing or just slightly less. To obtain this gain we must feed both dipoles in phase and that means connecting a feedline to both antennas. There are numerous ways to do this.  However a trick can be employed to use only one feedline. You can take a halfwave piece of wire ( upped dipole) and bend the ends down to meet the ends of the lower dipole that are bent up.This will insure that both dipoles are in phase. If the spacing between the dipoles is only a couple inches we have the common folded dipole. However if we increase the spacing to 1/4 wavelength and bend the ends of the upper dipole down and the ends of the lower dipole up enough to touch we have a full wave square or qu...