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

 
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post #1 of 3 (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 3 (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 3 (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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