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Old 2-Apr-2011, 6:32 PM   #9
retired17
Junior Member
 
Join Date: Mar 2011
Location: anaheim, ca
Posts: 13
Thank you all for your thoughts and comments on my original post on why my CM4228 (8 bay antenna) did not give me better results than the CM4221 (4 bay antenna).

I was directed to HDTVPrimer hosted by Ken Nist and I think I found the answers to my question. There are two reasons for degradation. Ken said that if two colocated antennas are not in a uniform field than you would not get the expected 3 dB gain when combined. Some of the stronger signal from one antenna will be reradiated out of the other. The problem is in the combiner and an explanation of why this happens is provided by Ken Nist.

The second source of loss is that a larger antenna with its narrower beamwidth will only see one multipath signal thereby losing the hot spot advantage. He said hot spots are good for reception since the hot spot signal could be up to 6 dB stronger. You lose some of this 6 dB if the antenna only sees one multipath signal.

My CM4228 antenna is composed of two colocated CM4221s mounted side-by-side with a combiner so it must be behaving in the manner Ken describes.

That is my understanding and I am satisfied with his explanation. Thanks again to Dave for directing me to Ken Nist's website.
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