Could someone explain?

[LoTech]

For the past few years I have struggling with getting a local channel on VHF channel 12 that is not provided on my Dish subscription.

Here is my report: http://www.tvfool.com/?option=com_wr...d243ffa853f900

I started with a noname antenna that was similar to a Channel Master CM3016, but the signal kept dropping in and out on my Dish receiver and TVs. About a year ago I upgraded to a Winegard HD 7084P. I get a lot more signal, but the signal still drops in and out.

A couple days ago I was playing around with a salvaged folded dipole I scavenged from an old antenna. It measures out to be about a channel 10 length. I mounted it to a piece of 3/4 PVC pipe about 4 feet long, and took a small tv out to the back yard. It turns out that I actually get a more reliable signal with this little piece of junk than I do the Winegard. I screwed the PVC pipe to a wood post about 5 feet from my Winegard at a height of about 10 feet, and patched the cable into my feed line to the house. The quality meter on my Dish receiver says that I get a quality of about 67 (constant) with the junk antenna, and with the Winegard I get about 85 quality, but it jumps up and down erratically, and causes the signal to be lost frequently.

Why would I get a more reliable signal with a junk piece of aluminum than a $150 antenna?

[ADTech]

My guess is that it's because the larger antenna is situated in a spot where it's subject to one of the following:

1. Excessive electrical/electronic noise noise or interference.
2. Multi-path.
3. FM signals, especially if you are using any sort of amplifier.


The key is this hint "85 quality, but it jumps up and down erratically, and causes the signal to be lost frequently" which indicates that the problem is something variable. If it were a defective antenna, you usually would not expect to see this behavior.

The question then becomes one of whether or not there is any rhyme or reason or pattern to the dropouts or if they appear to be completely random.

[LoTech]

I think multipath is the killer here. Its like a briar patch of signals (well really just one signal bouncing off 6 or 7 hills). I can rotate the Winegard through nearly 200 degrees and get a partially usable signal. I've had the big antenna all over the yard, and always good signal, but fluctuating quality. For some reason, the signal on the little loop doesn't fluctuate nearly as much as the big antenna. I don't know, but for three days now on the little one, I've had a steady 67 Q reading through two big thunderstorms. I may just leave the little one up and go with what works.

[Stereocraig]

Originally Posted by LoTech

I think multipath is the killer here. Its like a briar patch of signals (well really just one signal bouncing off 6 or 7 hills). I can rotate the Winegard through nearly 200 degrees and get a partially usable signal. I've had the big antenna all over the yard, and always good signal, but fluctuating quality. For some reason, the signal on the little loop doesn't fluctuate nearly as much as the big antenna. I don't know, but for three days now on the little one, I've had a steady 67 Q reading through two big thunderstorms. I may just leave the little one up and go with what works.

You could try a vibration test on the elements, w/ something non-conductive, such as a yardstick, but don't whack anything too hard.