722k OTA antenna height.

[milehighmike]

RG56 cable is not 75 ohm, it is used mainly for ham radio installations. TV antenna installations should use RG6 cable, RG11 for longer cable runs.

Antenna Web and DTV Answers are the last two sites I would go to for information. TV Fool (already mentioned in a post in this thread) and AVS Forum (has several OTA threads) are quality resources.

As far as antenna height goes, I have line of sight to a station 104 miles away. According to TV Fool, my signal strength increases as I lower my antenna. So higher isn't always better. The advantange of height is to get over obstructions - houses, trees, power lines, etc. Normal TV reception is generally limited to 60 miles over flat terrain due to the curvature of the earth. But factors such as differences in height above sea level and the actual height of the the transmitting tower, height above sea level at the reception location, mountains & hills in between, etc. can change that 60 mile standard dramatically, as is the case with the station I receive that is 104 miles from me. There are stations less than 50 miles away from me that I can't receive due to intervening mountains. While raising an antenna 10 feet may help, it probably will do very little regarding increasing the strength of the received signal.

Just my 2 cents.

 

[yosemitesam]

Too high an altitude

I am sure you have thought about the statement you made and found it is back ass forward

Rg 58,rg11 coax is used in ham and comm.app's approx.> 50 ohm Impedance. rg56, rg6 are us in T. V . transmission app's approx. >75 ohm impedance

 

[milehighmike]

See link: http://www.satelliteguys.us/old-voom-news-developments-archive/7506-quad-shield-rg-56-a.html

 

[yosemitesam]

See link: http://www.satelliteguys.us/old-voom-news-developments-archive/7506-quad-shield-rg-56-a.html

Quad shield is very rarely needed just in an environment where some other equipment MAY be affected by a slight amount of RF radiation - Good rg56 is swept at the factory for both impedance matching and leakage ! Almost all is 100 percent shielded, how does quad shield get 100 percent any better ? The gooey stuff talked about is added for direct burial cable to keep rodents from wanting to chew on it ! Yes it is a big pain in the ass to work with quad and flooded [gooey] cable

 

[milehighmike]

I'm not sure what point you're trying to make in your last post, and I'm not about to get into a lengthy "discussion" with you.

According to awcwire.com, the impedence of RG 58 coax is 53.5, for RG 56 it's 48, for RG 11 it's 75, and for RG 6 it's 76. As I'm sure you know, TV antenna systems use 75 ohm cable. That's why RG6 and RG11 are appropriate for TV and RG 56 and RG 58 are not. As far as shielding, quad or otherwise, I was never addressing that issue.

 

[yosemitesam]

I'm not sure what point you're trying to make in your last post, and I'm not about to get into a lengthy "discussion" with you.

According to awcwire.com, the impedence of RG 58 coax is 53.5, for RG 56 it's 48, for RG 11 it's 75, and for RG 6 it's 76. As I'm sure you know, TV antenna systems use 75 ohm cable. That's why RG6 and RG11 are appropriate for TV and RG 56 and RG 58 are not. As far as shielding, quad or otherwise, I was never addressing that issue.

The article is wrong if it states RG56 is in the 50ohm category period. Or the 1000 or so antenas we have put up would not work very good. channel master,winegard,Jerrold,Radio shack sell the wrong stuff for their antennas, I was an engineer for Jerold ! Check out below
Coaxial cable information

Most coaxial cables for video applications have a nominal impedance of 75 ohms. ... outer braid and jacket of an RG-59, RG-6 (RG-56) or RG-11 coaxial cable. ...
www.accesscomms.com.au/reference/coax.htm - Cached - Similar

 

[cditty]

59 can handle OTA, it just degrades faster over distance. You are far better off using RG6 or RG11, for distance. It will have less loss at the same distance. In digital audio, we use something called word clock to sync. It requires 75 Ohm cable and 75 Ohm terminators. Many people use 50 Ohm cable for short runs and it works fine for them. Now, with that said, I'm the type of guy who runs things on spec, so my word clocks are synced with 75 Ohm cable.

Long and short of this is science apart, if you are running less than 75 feet of coax, 59 will do you fine for OTA (DO NOT USE IT FOR SATELLITE). More than that, use RG6. Quad is only going to help with interference (ie, crossing electrical or lighting fixtures in your attic). FWIW, when I rewired my house, every TV Box got 3 RG6 Quad runs and 2 Cat 5e network interfaces. I don't believe in diplexers, as they are cheap and fail often. My OTA has a dedicated RG6 Quad run.

 

[Jim5506]

The signal strength of a received channel responds to the inverse square law. That is, for every four times you increase the height of the antenna, you potentially double the strength of the signal received.

Signal strength varies by distance according to the inverse square law, it has little or nothing to do with antenna height.

Signal strength will increase as height increases until line of sight is achieved then it is flat.

Below line of sight signal strength depends on many variables but the inverse square law is not one of them.

The major variable is frequency and how much that particular frequency is diffracted over the horizon, then your and the transmitter's distance to the diffraction point, ad nauseum.