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Discussion Starter · #1 · (Edited)
Hi as a newbie I've been lurking and reading...I was wondering if anyone had tried building a reflector for the RCA ant751. I have been looking at doing this mod and was wondering if in the experience of many on this board it would be worthwhile... I'll probably pick up a CM4228 in a few weeks ...but I like tinkering...I was thinking corner or parabolic, BTW a queen size bedspring doesn't really work all that great... If this post is in the wrong section I apologise...
 

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That antenna is a small Yagi style antenna which already has a reflector element on it. Not saying it maybe couldn't be improved for a particular channel but probably not much and most likely at the expence of reception other channels.
 

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.but I like tinkering...I was thinking corner
You could try a big corner reflector on it. Just get the biggest piece of 2" X 4" mesh fencing sectional piece you can and bend it in half. Corner reflectors need to be at least 1.5 X the wavelength wide and long to really start becoming into their own. (wider and longer than the existing reflector on it) But the bigger the better. :p And then experiment with the element to corner distance.
 

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Discussion Starter · #4 ·
reflector

Thanks, I did see a yagi though that had corner reflectors the Winegard 9095P ...thats why I thought it might help, because mine seems to have lost a little signal < 34 & SNR <16 so I've lost channels (coincidently since I installed the cm9521A rotor) and I did notice it picks up signal from the rear so I thought this might filter that out some...
 

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That antenna is a small Yagi style antenna which already has a reflector element on it. Not saying it maybe couldn't be improved for a particular channel but probably not much and most likely at the expence of reception other channels.
RCA ANT-751 is a Log-Yagi, where the back two elements are BOTH ACTIVE, interconnected by a
crossover feedline (like the YA-1713). Hence it does NOT have any passive reflector element(s).

Since the ANT-751 already has about 10 dB F/B Ratio, I would be surprised if a reflector could
"redirect" very much of what little rearward gain there is towards the front. Probably wouldn't
see much more than a dB or so of Gain improvement....on SOME freqs.....and perhaps worse on others.....
 

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I just tried using the reflector from a spare cm4228hd on the back of stacked rca ant751 and it seemed to help a little maybe 1-2 db.
 

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I just added a piece of gutter mesh material today that was about 6" by 18" to the back of this antenna since I had it just lying around and ready to drop at the recycling center. All of the channels I receive are about 100% strength and quality except for high vhf rf12. I was getting 100% signal strength but quality was varying between 62-69 %. After adding this mesh it is rock solid at 69-71% signal quality. So it did help high VHF. I just did it today so I will have to see the longer term ramifications. No impact to my UHF or other VHF stations which were 100/100.

Probably should try something longer than 18" if I can find some scraps lying around.
 

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RCA ant751 is VHF LPDA + UHF Uda-Yagi
You will break it, if put any metal near rear dipole (VHF LPDA first long dipole).

Even if ant751 was pure Uda-Yagi with single rod reflector, complicated reflector (1-axis parabolic, corner reflector) would not add more directivity/gain. I investigated this many times (mostly on much higher microwave frequencies, where dimensions aren't huge and high Front/Rear ratio is needed).

Corner/Parabola reflector add much directivity for pure dipole, or dipole with few director elements. You don't really need those few directors. If reflector alone gives let say 10 dBi, than any number of directors which alone give less than 10 dBi won't add more gain. And if directors alone give more than 10 dBi, than removing this reflector won't hurt gain. Apertures from large reflector and apertures from long Yagi structures DO NOT COMBINE.

Big corner/parabolic reflectors provide 2 benefits:
1) high Front/Rear ratio, clean rear lobe pattern
2) wideband (the only option if you need to cover old UHF band 470-862 MHz)
 
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