What Causes Dead Spots in Video Reception?

[gdmoore28]

I live out in the country and on the banks of a bayou. For some reason, there is a 1/4 mile long stretch on either side of our home which is a "dead spot" for all kinds of reception, especially Digital TV signals. I can literally watch my cell phone reception meter drop as I approach our home on the highway, then pick up again to full strength once this spot is passed. And this happens to all my close neighbors, too, regardless of their carrier.

On TV, I can receive about 12 channels, while my neighbor only 1/4 mile away can receive 52 channels, as can my uncle who lives 1/2 mile further down the highway. Both of them have short antenna poles, while mine is about 20 feet tall.

Distance from broadcast towers is not an issue. I can literally see two of them from my home, and the others are only 12-15 miles from our house. When I was still a farmer, we had to erect 50 foot towers here before our private band radios would work.

What is really curious about this is that FM reception here is excellent. I can receive very clear and strong FM broadcasts with only a wire antenna dangling from my receiver. I'm simply curious about what possibly causes these dead spots with bad reception across almost all the frequencies.

GeeDeeEmm

 

[hjames]

I know trees can cut back on reception of higher frequencies.
Modern HDTV is usually broadcast in the UHF frequency band, which is more attenuated by the moisture in tree leaves than low or high VHF

Not sure where you are in terms of line of site of hills/mountain/terrain between you and the broadcast towers, but "the banks of a bayou" sounds like you are in low lying terrain.

Likely there are other reasons - but foilage is a good one

VHF-Lo ch 2 - 6 54 - 88 MHz
FM Radio band 88-108 MHz
VHF-Hi ch 7 - 13 174 - 216 MHz
UHF ch 14 - 69 470 - 806 MHz

 

[Spitfirejoe]

I had one spot just outside of my place of employment that killed my cell phone reception. I'd start a phone call upon leaving the gate, and I'd get to that spot and the call would drop. It happened consistently enough that I started looking around at the other things in the area. Found overhead high tension wiring and wiring to a (different company's) cell phone tower that I passed under. Also have poor reception in my home, but right behind my house is a major power line system on tall poles leading from the city owned coal fired power generating plant that is 6 blocks south of me.

 

[gdmoore28]

Thanks so much for the help, folks.

The mention of cables has me thinking - our house was built in 1980 and was pre-wired for satellite TV. I'm wondering if the antenna cable that was used is adequate for digital TV.

GeeDeeEmm

 

[WobblySam]

I know trees can cut back on reception of higher frequencies.
Modern HDTV is usually broadcast in the UHF frequency band, which is more attenuated by the moisture in tree leaves than low or high VHF

Not sure where you are in terms of line of site of hills/mountain/terrain between you and the broadcast towers, but "the banks of a bayou" sounds like you are in low lying terrain.

Likely there are other reasons - but foilage is a good one

VHF-Lo ch 2 - 6 54 - 88 MHz
FM Radio band 88-108 MHz
VHF-Hi ch 7 - 13 174 - 216 MHz
UHF ch 14 - 69 470 - 806 MHz

And toss in a little wind to get those branches swaying and it can drive you nuts.

 

[j!m]