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Old 11-Jul-2012, 4:50 AM   #1
Junior Member
Join Date: Jul 2012
Posts: 9
New to OTA, requesting help (double edge diffraction?)

Hello All,

Here's a link to my TVFool signal analysis results:

I have a Clear Stream 2 (from Antennas Direct) outdoor antenna, currently installed (temp install) on a deck at a total height of 248 ft above sea level in the West Seattle area. There is 100' of RG6 cable direct from the antenna to my TV tuner with no disconnects or inline disturbances. I wrote temp install because I am still trying to locate the best area for reception, and the deck has been easier for me to iterate then my roof. Right now, the antenna is supported by an aluminum ladder, which may or may not be helping my reception. Going to my flat roof should improve reception (~10 ft higher), but my first and second attempts up there were worse then my several attempts on my deck.

I believe I have terrain issues and would like to understand double edge diffraction better, and understand how to best use the TVfool analysis in these cases. The deck is located on the NE side of my house, which is the correct side to "point" for the groups of towers that I desire to receive. There is a home and some trees direct to my North, but worse, a hilly terrain between me and the cluster of towers that I am trying to reach. Although I am not 100% sure, I believe that the height of the house and trees is outdone by the hilly terrain; I know from the TVfool analysis that I do not have LOS.

I would like to receive the following channels:

I currently get:
KCPQ 13, even though I am on the wrong side of the house pointing closer to 85 deg
*KUNS-TV 50 (surprisingly strong signal)
*KIRO-TV 51 (weak signal)

I put the two "*" above because I thought it was curious that I could receive those stations and yet cannot seem to obtain the other preferred signals. Channel 50, which has strong signal reception, leads me to believe that the other nearby towers in that general direction should also be obtainable.

I should add that when I try to point to the NNE (i.e anwhere 0 - 15 deg or so) I get overall less channels, and none of the ones in that NNE cluster). When I point to the NNE, I try pointing with a slight inclination to "see" over the house and trees, and I am wondering if this antenna must be oriented exactly vertically with no inclination. For some reason, going almost East and no inclination (85deg az), I get lots more channels, AND channel 50, which is the only thing giving me hope that I can eventually reach the preferred channels in that same cluster. I am thinking double edge diffraction is playing a roll here somehow, but I haven't a clue how to proceed.

To summarize, I have tried many attempts (inclinations and Az) to NNE with no luck, and am wondering if there's more science to the double edge diffraction, and if so where does science tell me to point?

Finally, and a little bit off of my intended focus, I would be interested in thoughts about just trying to get K47LG-D to my SW instead? I was told by an Antennas Direct operator that the station was probably not broadcasting anything desirable, but I think it might be another KIRO with a possible strong signal for my location. I tried calling a number that I found on the website, but I missed the business hours and will try that number again later.

Thanks in advance for any help,

Last edited by Seaboy; 11-Jul-2012 at 5:35 AM.
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