Additional 10 meter antenna info
While not a truly scientific test, I did a short test yesterday with two different ten meter antennas. I have a 10/15/20 meter trapped antenna horizontally polarized that was originally used as the driven element of a three element antenna. Now just a dipole. The other antenna is a homebrew dipole that is hanging vertical from my tower. The bottom is just a few feet off the ground. I am on top of the hill so this will make some difference but not much.
Monday afternoon after repositioning the horizontal antenna so it now favors the northeast–Ukiah is off the end of it–and hanging the vertical, I got on the air.
Listening on ten meters with the horizontal antenna I could hear some southern Mexico stations, Centeral American, and some Brazilian stations on it. Mind you, they were off the end of it so that was the LEAST favorable direction of the antenna. Switching to the vertical made no or very little difference in signal strength. Thus the received signal had to be coming in from a higher angle of radiation so that it got both antennas about the same. A bit later while on the vertical I heard a weak but readable signal from San Francisco. A contact was made and when I switched to the horizontal antenna, all was lost.
As this signal was coming on the horizon, and was vertical polarized, it shows that for local ground wave the polarizations should be the same for maximum signal transfer. The cross polarization from horizontal to vertical will lose allot–typically 20 to 30 db–over the short distrance while not losing so much over the long skip distance.
Just a note, nothing scientific or so. It does show that the need for some of us to have both polarizations is indeed a fact. My problem is that my vertical antenna is causing me audio rectification in the computer speakers. Need some chokes.
Just an observation. Ten has been pretty good about noon on here as has fifteen meters.