Aluminum Reflecter - Canadian TV, Computing and Home Theatre Forums

 
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post #1 of 8 (permalink) Old 2017-02-28, 09:05 AM Thread Starter
 
Join Date: Oct 2007
Location: Burlington (Upper) ON
Posts: 29
Aluminum Reflecter

Hi, I have seen in some YouTube videos people placing some sort of board or panel by their antennas , covered in metal sheeting or even aluminum foil. which they claim boosts their signals.

Is there any truth to this being useful ? I am sceptical but would be interested in knowing if any improvements could be made this way.

Thanks

Cord Cutter -> OTA: Clearstream C2V, Channel Master 3414,
Stream -> Apple TV, Chromecasts , Android box.
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post #2 of 8 (permalink) Old 2017-02-28, 09:46 AM
 
Join Date: Jan 2012
Location: King and Bathurst, Toronto
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It doesn't boost the signal, per se. But, reflects the signal back onto the active elements.
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post #3 of 8 (permalink) Old 2017-02-28, 10:03 AM Thread Starter
 
Join Date: Oct 2007
Location: Burlington (Upper) ON
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So it might be useful after all. Thanks.

Cord Cutter -> OTA: Clearstream C2V, Channel Master 3414,
Stream -> Apple TV, Chromecasts , Android box.
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post #4 of 8 (permalink) Old 2017-02-28, 02:02 PM
 
Join Date: Nov 2009
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Only in the hands of someone who either knows how it works or someone who just happens to get lucky without having any understanding.

Your antenna already has a reflector.
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post #5 of 8 (permalink) Old 2017-02-28, 02:04 PM
 
Join Date: Jan 2012
Location: King and Bathurst, Toronto
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Very useful. It also has the effect of lowering the SWR of the antenna, if I remember correctly. But, for the most part it will help your antenna capture more of the signal.
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post #6 of 8 (permalink) Old 2017-02-28, 03:59 PM
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Placing a Reflector behind a Bi-Directional Antenna [Gain in Opposite Directions, such as typical FLAT indoor Antenna], will reduce reception of Multipath and Interference from the REAR Hemisphere and increase Forward Gain by about 3 dB....turning it into a DIRECTIONAL Antenna. It it ALREADY has a Reflector, adding a SECOND Reflector MAY or MAY NOT improve performance....but probably not by much.

I conducted 4nec2 Antenna Simulation Analyses of mclapp's Optimized M4 (9.5x9.0) 4-Bay Bowtie Antenna with different Reflector-To-Bowtie Separations. UHF Gain was slightly higher at 4.5-in Separation, however the SWR was higher than desired [and gets worse for smaller Separations]. At 6.5-in Separation, there was significantly Lower UHF Gain and hence also lower F/B Ratio...with the lowest SWR. BEST Compromise [favoring minimal degradation to UHF Performance] was at about 5.5-in Separation:
M4 (9.5x9) + Various FLAT Refl. Widths

Then I conducted Comparisons of different Reflector WIDTHS for an assumed Reflector-To-Bowtie Separation of 5.5-in. UHF Performance continues to increase as the Reflector Width Increases, HOWEVER, Good Hi-VHF Performance requires a Reflector Width of AT LEAST 32-in, because at small Widths, Hi-VHF Gain will be either more or less SAME toward Front and Rear.....or HIGHER towards the REAR on Lower Channels. Increasing HEIGHT of the Reflector continues to improve UHF Gain, but fairly slowly after it extends beyond the Bowtie by a couple inches. [This performance PROBABLY is very similar for the various TOO SMALL Flat Panel Antennas.]

I also found that using a Reflector-To-Bowtie of 16-in was a GOOD COMPROMISE between "Adequate" UHF Performance and GOOD Hi-VHF Performance (esp. an almost Acceptable SWR):
UHF M4 (9.5x9.0) 4-Bay+FLAT Grid at 16"

There would be only a small difference in performance between the modeled Screen Grid with 1"H x 2"W openings and a SOLID piece of Metal or Aluminum Foil.

Compare to Optimized M4(9.5x9.0) WITHOUT Reflector:
http://imageevent.com/holl_ands/multibay/4bay/superm4

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands
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post #7 of 8 (permalink) Old 2017-03-01, 07:26 AM
 
Join Date: Mar 2016
Location: sainte-marthe-sur-le-lac, QC (Canada)
Posts: 31
Hi holl_ands,

I was wondering if the vertical spacing between the rods have any effect on UHF or Hi-VHF signal quality?

For instance, my "Vs" dipoles are 4" tip-to-tip and I use 2 rods(32" width) separated at 4" vertically (2 rods behind each bay). Works excellent on my Rf13 but once I added an extra rod in the middle (2" vertical separation and 3 rods per bay), I notice a slight decrease in VHF-Hi Rf 13 but UHF got stronger. I might be dreaming or maybe I should give it another try? The bays are 5 1/2" away from the reflector rods.
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post #8 of 8 (permalink) Old 2017-03-01, 03:06 PM
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I did a Parametric Study for different number of Reflector Rods with mclapp's M4(9.5x9.0).....basically a linear improvement in Gain & F/B Ratio for BOTH UHF and Hi-VHF as the Rod-to-Rod Separation was decreased to about 1.33-in [MORE IS BETTER]. And a slight LOSS in Hi-VHF F/B Ratio when R-R Separation reduced to 1.0-in:
M4 (9.5x9) + Various Number of RRs - OPT
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