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Discussion Starter · #1 ·
I live just outside of Harrisburg PA. Our local HD is PBS, and a NBC affiliate. Baltimore is 65+ miles away, but a small mountain range is between us.

Hoping to get Baltimore, and needing an outdoor antenna, I bought a CM4228A. I propped the antenna up on my back deck. Then playing around I noticed that I was getting Baltimore Analog UHF on my TV.

So using the tuner on my TV I peaked the antenna to "Baltimore". I then hooked the antenna to my Dish 6000, and was able to lock CBS (after much messing around). I could only lock the NBC(WBAL) station for a few seconds at a time, and only after I hooked up a Sparten 3 amp. None of the other stations would lock. I was able to watch Family Law with only 3 or 4 dropouts.

Questions:

Is the reception due to refraction?

Why some stations and not others?

Will mounting the antenna higher help, or was I just really lucky last night?


Best Regards,




[This message has been edited by Swampfox (edited 05-01-2001).]
 

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I have a look angle of just under 2 degrees to the TV towers 30 miles away.


But, I have a look angle of 13 degrees to a ridge about 400 yards away.


So, no line of sight reception.


I am using a JBX21 antenna from Blake Aerials in the UK. The antenna is horizontal (I haven't tried tilting yet). This antenna has an extremely narrow horizontal beam width (9 to 11 degrees over the UHF band), and a gain of about 12db ref to a dipole.


With this setup I receive five of the LA stations (42,53,59,65, and 66) quite well, but I get nothing on 60 and very little on 31,36, and 43. These stations all broadcast from towers on Mt. Wilson and are located within about a mile of each other.


I can only believe thyat the reception I do get is from diffraction over the ridge.


Glenn has reported a similar situation and he was able to bring in a station not otherwise receivable by tilting his antenna slightly over the top of his ridge.
 

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Swampfox,


There will be a significant difference if you mount the antenna on your roof on a mast. Setting the antenna on a deck is fine for some general debugging but the near field effects of the deck will degrade the performance. The antenna needs to be in the clear and it needs to be away from the surface of the roof by at least 5-6 feet. If you use a 6-10 foot mast on top of your roof mounted in a simple Tripod roof mount you should see a dramatic improvement. Anything over 10 feet and depending on the wind and weather in your area you might have to use guy wires. I am 45 miles from the transmitting tower in the San Francisco area. I have a Radio Shack Yagi antenna mounted on a 6 foot mast on top of a 2 story house. My view is relatively unobstructed although I do aim between some trees and a power pole. I clearly receive all of the signals being transmitted from the San Francisco tower. (about 7 channels) plus I get a couple in San Jose off of the backside of the antenna.


In your case, with a ridge between you and the transmitter, you will want to play with the aiming of the antenna. You may see a signal improvement by aiming directly at the ridge although if the ridge is 40 miles away, vertical aiming may not be needed because the vertical beamwidth of the antenna should be adequate to pick up the signal that is being diffracted as it goes over the ridge.


..Doyle
 
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