In the analysis
http://www.tvfool.com/?option=com_wr...267e94071d7e20
all the stations of interest to me are shown LOS from Mt. Wilson (where all the transmitters are). I can see it on a clear day east and slightly south, about 100 degrees, 25 miles away.
But pointing my antenna there, all the signals are too weak. We have to point our antenna east and slightly north, at about 70 degrees for usable signals. I think we're getting mostly bounce off the mountains rather than line of sight signal, or some combination. Apparently the analysis can't take this into account. I can't think of any other reasons.
Almost all the channels 2 through 62 are good. However, we're still getting dropouts on a few channels when atmospherics change with weather, like when we get very hot day. Rather than increased attenuation of a fixed path, this is probably due to the signal path changing. Then the apparent direction of the transmitter moves to the side of my antenna's beam, where the antenna's gain is less and the signal output diminishes.
The (virtual) channels that disappear frequently for long intervals are 22, 34, 52, 58. 58 is worst; KLCS (L.A. schools system) doesn't have the best equipment. I've heard that tuners have more trouble with its signals when they are weak. Channel 7 is odd because it fluctuates quickly while the others fade, even though the signal strength on the converter is at the low end of Good.
According to the analysis, 52 and 7 near the top of the list should be strong but but they're not adequate all the time. 58 is about halfway down the list, at the top of the red area, so it is definitely weak and comes and goes more often. I'm not interested in any of the stations further down in the red area.
I currently have Winegard's CA 7078 antenna and AP4700 amplifier, 4 way splitter, 75 to 100 ft of RG6 coax, 3 Digital Stream DTX 9950 digital converters, and a Samsung flat panel with built-in converter. Our antenna is 15 ft above our single story house, which puts it 35 ft above ground, just above the top of the hill across the street.
We need a stronger signal, so it would seem like a higher gain antenna is the obvious solution. However, a higher gain antenna would also have a narrower beamwidth. If the beamwidth of the new antenna is too narrow and the apparent direction of the transmitter shifts too much, it could even fall outside the antenna pattern. It looks like we're now pointing about 30 degrees north of line of sight. I can't guess how much the apparent position shifts with weather, but maybe you can. Probably not a lot, since only a few channels are affected. So, there's hope that the right combination of antenna gain and beamwidth could work.
The amplifier is making up for the transmission line loss of the cable and the splitter, and trying a stronger amplifier didn't help on the weakest channels. Clearly I need more signal output from the antenna.
Will any of the newer "digital TV" antennas solve the problem? Which one?
I've also thought about a really high gain antenna pointed LOS at 100 degrees, with a narrow enough beam to ignore the stronger signals at 80 degrees, but this sounds like fighting nature and doing it backwards. This would require a very large antenna, which would be a hazard in the high winds we experience here.