I am having issues at night. It's only with channels 11 and 13. During the daytime, all my channels are 100%. At night, channels 11 and 13 will "drop out" about every 30 seconds. When it drops out, it lasts about 1 second and then it's fine again. If I watch the signal strength while this happens, it goes from 100% to about 20-30%, then back to 100%.
I have read other articles discussing how pressure changes at night can affect antenna reception, but I'm not sure that this is the only culprit. Wouldn't pressure changes be affecting all channels? I know my antenna is pointed the correct direction because I aimed it using a magnetic GPS compass.
Something else that concerns me is the antenna's upward/downward angle. What should it be set? Is there a scientific approach? Or, just guess work? Like I said before, in the daytime, everything is 100% perfect all the time. At night, only 11 and 13 mess up.