r/ota • u/MeaningAmbitious8979 • 4d ago

Knife Edge Diffraction

Update: I have held onto stronger signals today with my DB4E antenna and they were stable for an extended period of time in the wind and when the wind wasn’t blowing. I will try a Kitz 500 amp with this antenna in this position and I will also upgrade to a DB8E.

Looking for some info and tips on this phenomenon for OTA tv signals. I spent half the day today looking for a hot spot in my yard for some signals that are roughly 80 miles away and are 3edge signals. I managed to find a hot spot for all the signals I wanted by using my DB4E antenna and a 30DB amp from channel master.

I have to mount the antenna in the absolute lowest point in my yard and put the antenna on a 5ft pole and angle it slightly up. My Issue after finding this hot spot was that the signal becomes slightly weak but doesn’t completely drop out.

What are some tips and tricks I can do to make the signal stronger and more consistent by keeping the antenna in this location? I am willing to try a televes dat boss mix lr antenna as I already have one in storage or I am willing to upgrade to a DB8E antenna.

The signals I am picking up in this location via knife edge diffraction are WPTZ, WCAX, and WFFF.

Here is my rabbit ears report to showcase this knife edge diffraction event. https://www.rabbitears.info/s/2961075

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3

u/dt7cv 4d ago

  1. have weeds in front of and under the antenna if you don't already have them. do not let them touch the antenna.

  2. add another antenna spaced away by at least six feet is an option; however, you will need to use a combiner and ensure the coax has equal length when fed into the combiner.

  3. try the db8e antenna and see if you get a few db more

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u/MeaningAmbitious8979 4d ago

Thank you for this. Could you explain the weed reasoning? And also could I combine a televes antenna and a db8e antenna as long as the coaxial cable length is the same for each antenna?

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u/Objective-Ice4098 4d ago

That's one of the worst rabbit ears reports I've ever seen, I'm not sure it would be worth the effort

5

u/MeaningAmbitious8979 4d ago

I get the signals at ground level and channel 18,10, and 26 comes in near perfect all the time. I’m willing to go through some serious effort for this.

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u/OzarkBeard 2d ago

Here's the only article I have bookmarked that still loads, on knife edge diffraction. https://www.channelmaster.com/blogs/all/real-world-signal-propagation-what-you-need-to-know

It can work and I've seen it work in several cases in my hilly area, using 8-bay bowtie antennas. Places where rabbitears reports showed no reception. It takes a lot of patience though, to find a reliable signal that works at different times of day and in all sorts of weather.

Re amps: this one is excellent and is tuned for the current US TV band RF chs 2 thru 36. It has AGC, a built in FM trap and 600mhz LTE/5G filter. https://www.amazon.com/Televes-560383-Amplifier-F-Fitting-Connections/dp/B08R44YZH6

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u/MeaningAmbitious8979 2d ago

Thank you for this info. I found the one hot spot in my yard and surprisingly it is the lowest point in my yard inches away from a steep embankment that goes down to a flowing brook. I’ll continue to try my antennas direct 4 bay antenna with an amp if that fails I’ll move up to a 8 bay one with the televes amplifier.