Central Oregon OTA Antenna Recommendation?

[Tugboat]

Roof antenna recommendation with these coordinates?
Flat farmland area.

http://www.tvfool.com/?option=com_wr...a3623eea1a2046

Thanks,
Tugboat

[John Candle]

How many Tv's connected?

[mtownsend]

Hello and welcome!

It looks like there are three groups of transmitters for you to consider...

1) KOAC (PBS, channel 7 / 7.1) and K14GW-D (Fox / MyN, channel 14 / 34.1) broadcast from Corvallis around compass heading 263º. These are two of the closest and strongest transmitters in your area. These stations are going to duplicate much of the programming you'd get from the stations KEPB and KLSR broadcasting out of Eugene.

2) Most of your "local" stations are broadcasting from Eugene around compass heading 170º, roughly 40 miles away. These signals are reasonably strong, so you should have no problem getting them with a rooftop antenna.

3) Several of the Portland stations are also available to the north (compass heading 356º, about 64 miles away). These signals are weaker due to some terrain blockage and the greater distance, but they are still within reach if you use a high gain antenna.



I would suggest two possible setups, depending on what's important to you:

I) If you are content with just the Eugene stations, then you can use an antenna like the Winegard HD7694P or Antennacraft HBU-33 pointed south. Since you should be able to pick up KEPB and KLSR with this setup, there is probably no need to worry about the two transmitters in Corvallis.

II) If you want to get the Portland stations as well, then you will need to have an antenna rotator (like the Channel Master 9521A) or an A/B switch to deal with stations coming from multiple directions. The weaker Portland stations will require a larger antenna like the Winegard HD7697P or Antennacraft HBU-55. If you use an antenna rotator with this kind of antenna, you should be able to pick up most of the stations down into the "red" zone on your TV Fool report by turning your antenna to the appropriate direction. You should be able to get Portland, Corvallis, or Eugene stations this way, but you cannot get them all at the same time (because the antenna can only point to one group at a time).



If you plan on splitting the signal to multiple rooms, or if the length of coax is going to be long (more than say 50 feet), then I would suggest also adding a mast-mounted pre-amp like the Channel Master 7777, Winegard AP-8700, or Antennacraft 10G202.

[Tugboat]

One TV

You pretty much confirmed what I thought because of the split between Corvallis, Eugene and Portland transmiiters. About how high do you think we need the outdoor antenna to be to pull in the Portland stations reasonably well?

You answered my most important question and that was, 'which antenna would be best for Portland?'

Thanks so much for the reply.

[mtownsend]

Originally Posted by Tugboat

About how high do you think we need the outdoor antenna to be to pull in the Portland stations reasonably well?

You need to have the antenna high enough above your own roof to make sure the roof itself does not interfere with the performance of the antenna. Ideally, you want to have the antenna at least about 4-5 feet above the average roof line in your neighborhood.

In special situations where there is a nearby obstruction (e.g., a tall building or hill in the way that is less than half a mile away), then some extra height might make a significant difference. When the main obstruction is close by, a little bit of height can change the angle at which the signal must diffract (or bend) over the top of the obstruction. Signals cannot diffract well at sharp angles, so reducing the diffraction angle results in more signal power reaching the antenna.

However, in your situation, the nearest major obstruction appears to be several miles away. In this case, adding height makes very little difference at all. Adding 10, 20, or even 50 feet will barely change the diffraction angle for an obstruction that's ~12 miles away, so I doubt that you will see any significant change in signal strength.

If you want to try some what-if scenarios, then you can try out our Interactive Maps feature (here). In this tool, the list of channels and their Noise Margin values (shown below the map) will automatically update when you enter different values for the antenna height. You can see if there is any significant change in signal strength for the channels you want.

I think that for your situation, being 4-5 feet above your own roof is probably all that you need.