Updated TV Antenna Thoughts

[buckeyefarmer]

Im not getting one station, has always been tough to get.

 

[k0ua]

Interesting that channel 13 at the same distance and same azmuth (bearing) is transmitting with 20 kw instead of 1000 kw and is projected to have a 12 dBm difference in signal you have marked in blue (good) yet the much more powerful signal from channel 6. Granted it is 48 meters lower in elevation, and the actual RF channel is 50 (UHF) instead of 13 (hi band VHF), but I would have thought it wouldn't have made as much difference. But I guess it does.

 

[MossRoad]

Interesting that channel 13 at the same distance and same azmuth (bearing) is transmitting with 20 kw instead of 1000 kw and is projected to have a 12 dBm difference in signal you have marked in blue (good) yet the much more powerful signal from channel 6. Granted it is 48 meters lower in elevation, and the actual RF channel is 50 (UHF) instead of 13 (hi band VHF), but I would have thought it wouldn't have made as much difference. But I guess it does.

It's got 50 times the power?

 

[k0ua]

It's got 50 times the power?

Yep, according to the chart. 1000 KW ERP. Versus 20KW ERP. So yeah 50 times the power. Of course 50 times the power is not as much as you might think.

Lets look at the S meter on a standard communications reciever. Each S unit (if it used the old standard Collins calibration) is 6 dB

Going from 20 Kilowatts to 1000 Kilowatts is 17 dB of power increase So we are talking about almost 3 standard S units as you would see the signal on a communications receiver. So like S5 to almost S8. Or if a 20 KW signal was S9, the a 1000 KW signal would be 17 dB over S9. Those of you that have operated communications receivers hopefully this gives you some "feel" for this. Remember the dB scale is logarithmic. Those huge gains in transmitter power or antenna gain may not make as much difference on the receiver end as you at first think.

 

[MossRoad]

Yep, according to the chart. 1000 KW ERP. Versus 20KW ERP. So yeah 50 times the power. Of course 50 times the power is not as much as you might think.

Lets look at the S meter on a standard communications reciever. Each S unit (if it used the old standard Collins calibration) is 6 dB

Going from 20 Kilowatts to 1000 Kilowatts is 17 dB of power increase So we are talking about almost 3 standard S units as you would see the signal on a communications receiver. So like S5 to almost S8. Or if a 20 KW signal was S9, the a 1000 KW signal would be 17 dB over S9. Those of you that have operated communications receivers hopefully this gives you some "feel" for this. Remember the dB scale is logarithmic. Those huge gains in transmitter power or antenna gain may not make as much difference on the receiver end as you at first think.

Thanks!

 

[MossRoad]

I was missing out on the term ERP. Went and read up a bit. Makes more sense now. I was confusing transmitter power with ERP. Man, I'm rusty.

 

[California]

Interesting that channel 13 at the same distance and same azmuth (bearing) is transmitting with 20 kw instead of 1000 kw and is projected to have a 12 dBm difference in signal you have marked in blue (good) yet the much more powerful signal from channel 6. Granted it is 48 meters lower in elevation, and the actual RF channel is 50 (UHF) instead of 13 (hi band VHF), but I would have thought it wouldn't have made as much difference. But I guess it does.

I wonder if the higher frequency is the difference. I lost all of the San Francisco stations when they moved up to UHF a few years ago. Lots of tinkering with various antennas - nothing.

SF is over the horizon so apparently all my VHF reception was reflected off the atmosphere, and higher frequencies don't bounce as well.

 

[lakngulf]

I wonder if the higher frequency is the difference. I lost all of the San Francisco stations when they moved up to UHF a few years ago. Lots of tinkering with various antennas - nothing.

SF is over the horizon so apparently all my VHF reception was reflected off the atmosphere, and higher frequencies don't bounce as well.

That is what I am hoping. Guy helping has narrowed it down to that, thinking moving antenna to back of house will probably make no difference but raising antenna might.
Also a move to the back may hinder Montgomery stations to the south.
I should be able to raise it a good 10 feet, just got to get back up there with some help.
One other note: I installed in the fall/winter = no leaves on trees. Got fox 6 good and thought I had it fixed with exact antenna pointing. But now with spring I get nothing on that station.

 

[prichard]

If you click on one of the channels there's a terrain view at the bottom of the chart. See how that varies for the bad stations vs good that are in the same direction. That may help to see if height will help.

 

[lakngulf]

If you click on one of the channels there's a terrain view at the bottom of the chart. See how that varies for the bad stations vs good that are in the same direction. That may help to see if height will help.

I have several station towers grouped at 11 degrees on the map. I can get it to show 58 34 and 13 but cannot seem to find 6 to click on. That is a neat feature