CM4040 Type Antenna Designs - Canadian TV, Computing and Home Theatre Forums

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post #1 of 9 (permalink) Old 2017-01-10, 03:37 AM Thread Starter
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CM4040 Type Antenna Designs

I knew antennas like the Zenith Silver Sensor and Channel Master CM4040 designs made great indoor directional antennas, but a local antenna installer has adapted this as an outdoor antenna as well. How good as these compared to a 4 or 8 bay UHF outdoor antenna design ?

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post #2 of 9 (permalink) Old 2017-01-10, 03:23 PM
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A couple months back, I bought the CM-4040, a 5-Element Yagi [NOT an LPDA like I first thought], when it was on half-price Sale, separated it from it's base and threw it on top of one of the four stacks of papers next to my Stressless Recliner with the intention to Model it. I just now retrieved it from what is now the MIDDLE of that stack, along with a few other pictures of Antennas I want to Model. I copied it and will cut out the Outline so I can trace over it, using 4nec2 Geometry Builder to construct a 4nec2 Model and let you know in a few days. BTW: After removing two screws, I see that the "Fatter" Rear Element is a REFLECTOR, with the ACTIVE Dipole in front of it fed thru a very small and hence somewhat inefficient [probably 1:1] Ferrite Transformer Balun and the three smaller Elements on the Front are Passive Directors....which are TOO CLOSE together for Optimized Gain.

BTW: It is NOT designed for OUTDOOR use. Unprotected Coax connection to Balun can let in moisture [degrading the short piece of Coax as it seeps inside] and connection to ACTIVE Dipole is via a low-reliability pressure contact between pieces of Copper [connected to Other end of Balun] and some sort of metallic etch [which already appears to be degrading] applied to the two halves of the Dipole.

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands
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post #3 of 9 (permalink) Old 2017-01-10, 06:56 PM Thread Starter
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I guess I can weatherize the balun area with silicone.
The installer is experienced antenna and satellite dish installer with over 25 years of experience.
Here in Montreal the winter elements can be brutal with freezing and thawing cycles.
I wanted to capitalize on his choice of antenna, this way I can use the same antenna model for both indoor and outdoor applications since I can source these CM4040 design for pretty cheap overseas.
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post #4 of 9 (permalink) Old 2017-01-21, 07:17 PM
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CHANNEL MASTER CM-4040 4nec2 ANALYSIS:

4nec2 Analysis for CM-4040, a 5-Element FLAT Yagi, can now be found here:
http://imageevent.com/holl_ands/yagi...Yagi - CM-4040
Boom Length = 8.33-in [VERY Compact]

UHF Gain = 7.2 to 5.9 to 7.1 dBi, F/B & F/R Gain = 6.0 to 22.7 dB and SWR (75-ohms) Under 3.1.
Note WIDE BEAMWIDTH Azimuthal Antenna Pattern with 70-60 degree Beamwidth, deceasing with Frequency.

Nearly Bi-Directional Hi-VHF Gain = 2.3 to 1.8 dBi FORWARD and 2.5 to 2.2 dBi to REAR is slightly HIGHER is about same as a Hi-VHF Dipole or Rabbit-Ears. But Hi-VHF SWR (75-ohms) is Very EXCESSIVE.

UHF Gain is nearly as high as Solid Signal HDB-2X 2-Bay Bowtie [it's PCB Balun attenuates Hi-VHF], and is comparable to my DIY Optimized UHF 4-El-Pair FLAT-Enh1 FFDLA [8.5-in Boom Length] as well as [several inches longer] Zenith Silver Sensor and Terk HDTVi/a 7-Element LPDA's [Terk has Rabbit-Ears for VHF]...and 3-4 dB lower UHF Gain than A-D C2/C2V [C2V has Rabbit-Ears for Hi-VHF]:
http://manuals.solidsignal.com/hdb2x-gainchart.pdf
http://imageevent.com/holl_ands/zigzaglpa/uhflpda
http://imageevent.com/holl_ands/loop...taperedloopc2v









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Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands

Last edited by holl_ands; 2017-01-21 at 08:04 PM.
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post #5 of 9 (permalink) Old 2017-01-21, 07:25 PM
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Compare to: OPTIMIZED 5-El FD-YAGI with UNCONSTRAINED BOOM LENGTH:
ONLY Optimized for UHF Band Performance. Should improve Hi-VHF if JOINTLY Optimize UHF and Hi-VHF Band Performance.
Optimized Boom Length = 22 inches.

UHF Raw Gain = 7.3 to 9.4 to 8.9 dBi, F/B & F/R Ratio Min. = 13.4 dB (GOOD) and SWR under 3.1 (GOOD).
Note well formed Azimuthal Antenna Pattern with 70-50 degree Beamwidth, deceasing with Frequency.

Nearly Bi-Directional Hi-VHF Gain = -0.5 to 0.4 dBi FORWARD and -0.4 to 0.6 dBi to REAR
is slightly HIGHER and nearly OMNI-Directional. But Hi-VHF SWR (300-ohms) is Very EXCESSIVE.

PS: Jointly Optimizing UHF and Hi-VHF should improve Hi-VHF performance, perhaps at expense of UHF.











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Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands
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post #6 of 9 (permalink) Old 2017-01-22, 09:39 AM
 
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I gotta say, this thing looks pretty cool in this photo. Maybe most of you don't find it but I think it's kind of interesting. I don't know if it works better than the others or not, guess I have to buy one and check that out. How about I install it on an RV?
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post #7 of 9 (permalink) Old 2017-01-31, 06:13 PM Thread Starter
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Wow, thanks for the awesome analysis !
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post #8 of 9 (permalink) Old 2017-01-31, 06:16 PM Thread Starter
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Yeah it would be great for RVing, make a fold down version of this.
I source them to around $3.50-$4.50/100. Stores usually retail them for around $25.00usd
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post #9 of 9 (permalink) Old 2017-01-31, 06:26 PM Thread Starter
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More photos of the customized CM4040
Got rid of a Yaghi rotor setup


The neighbor wanted one too !


He tweaks it with a spectrum analyzer
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