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View Full Version : Double edge diffraction huh?


snoopysbuddy
27-May-2010, 8:31 PM
Just moved into a new house. Went to Best Buy and picked up the longest range antenna there - the ClearStream 2. The antenna is presently sitting on top of a cabinet on the second floor. The signal analysis tells me all channels are grey zone at best with path of double edge diffraction. Here is the link.

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d9fbeb6d4c0b87a

I tried pointing the antenna NNW but that gave me 0 channels. Pointing it NNE gave me 5 channels, which is counter intuitive since broadcast stations are from Mt. Wilson, which is NNW of my location. Pointing NE gave me nothing. Pointing SW gave me the same 5 channels. Geographically, my house is the on the south side of a hill so I have no LOS. Further south is another hill. Then I noticed the report shows double edge diffraction. So where does that mean I should point the antenna? Is the clearstream 2 suitable for this? I saw Lowes selling an RCA outdoor antenna (ANT3036X) - would that be more suitable?

I have not ventured into the attic yet but plan to do that this memorial day weekend. HOA won't allow antennas on the roof, so that's not an option. Any advice?

teleview
27-May-2010, 9:36 PM
HOA's and Etc.. . Know that you have the legal right to install a Tv antenna or other antennas on your roof , however they will try and put the scam on you and make you believe that you can't. . . This is one of the few government documents that is easy to understand and what this document says is , YES YOU CAN , and no they can not stop you. Some slow learners have to read this law several times to understand that Yes You Can. . http://www.fcc.gov/mb/facts/otard.html . . All HOA's , Housing Covenets and Etc. . have this legal document and have had this legal document for a long time. Even so , they scam those that are not aware.

Tigerbangs
27-May-2010, 10:54 PM
Now that we have established that you CAN install an antenna system on your roof, the question remains "what to install" and do you want to install on your roof?

Neither antenna that you have suggested is suitable for your situation.

You are in a difficult location that is severely cut off by a mountain range, and while you are not that far from the Mt. Wilson, you have a badly obscured view of the transmitters. Your situation calls for a deep-fringe antenna system if you want to pick up the LA channels, and, even with such an antenna system, you may still have difficulty with some stations such as KNBC and KCET. Please let us know if you want to proceed, and I can detail what you'll need. here is a photo of the proposed antenna system:

teleview
28-May-2010, 7:02 AM
Go to the >>STARTMaps<< part of tvfool , put in your exact address. You can change the Antenna Height up and down and can also move the Red Balloon Pointer location around.

teleview
30-May-2010, 10:11 PM
Diffraction is when the Tv signal is obstructed by something in the way , like hills , mountains , tall buildings. What happens is , signal is bent slightly and a small amount is angled scattered down ward. Probing with a Tv antenna on a pole is the way to find the hot spots of the scatter. The shorter the distance behind the obstruction , the less scatter there will be , the longer the distance behind the obstruction the more scatter there will be.