Originally Posted by MSZ 007
I have not given up just yet and will keep trying different locations on both north and south sides. Based on my signal strength fluctuations, is that consistent with multi-path issues? Or is it something else? The fluctuations happen on all channels. Signal strength will be great for about 5-10 minutes and then drop out completely for a few seconds to a minute at a time. I can make a video of what I'm seeing if you'd like.
A video might be interesting if you have the time.
There are several factors causing the fluctuations. Your signals are not direct LOS because of terrain interference; they are scattered which causes multipath. But most important, they are Tropo signals, which means they would go off into space and never reach you were it not for Tropospheric Propagation which creates a duct that carries them to your location.
The best signals I've received so far have been with KNSD and KSWB. SNR has been in the mid to upper 20's for both stations. I've also noticed the signals are best once the sun goes down. They will however occasionally go from a really strong signal (SNR 28) to nothing at all about 3-4 times an hour. Also during the local news broadcasts in the evening the signals fluctuate quite a bit. For me day time and evening reception has to improve in order to justify keeping the antenna up. I'll keep trying though!
The formation of a duct is dependent upon weather conditions, primarily a temperature inversion, which varies according to a 24-hour cycle. I suggest you look at the video by Gordon West about Tropospheric Propagation. It's about ham radio signals making it all the way from Hawaii to California, but the signals are on frequencies similar to TV signals.
Gordon West Explains Tropospheric Ducting
The formation of the ducts is explained beginning at about 22:02 in the video.
Tropospheric DX Modes
Most likely: 3) TROPOSPHERIC SUPER-REFRACTION (TrE), in your case
Figure 7 - Surface and Elevated Ducts
The optical equivalent is a mirage:
As far as mounting to the south side, it was just an easier installation. There aren't any obstructions in the SE corner. No tall trees or buildings in the distance. I also didn't have to go as high since I don't have to clear the peak of my roof. The mast is at 18' on that side. The two story house two doors down to the south is also not in play since its roof ridge is about the same height as the house directly next to me. Do you think going a little higher would help though?
The general rule is higher is better, but because of layering, there will be hot and cold spots as you move up and down as I showed you earlier. You just have to try it.