Confused about GH feed gap, 44-45mm or 85-95mm? - Canadian TV, Computing and Home Theatre Forums

 
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post #1 of 4 (permalink) Old 2011-09-12, 03:12 AM Thread Starter
 
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Confused about GH feed gap, 44-45mm or 85-95mm?

Confused about GH feed gap, 44-45mm or 85-95mm?

Does anyone have the "graphs" that compare the difference between them?


edit: I found this picture, but it has all the 10-160mm (I only want, ie: 45mm, 85mm, 95mm) and no CH #, it uses Mhz instead.

http://img81.imageshack.us/img81/442...bghrawgain.jpg

thanks
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post #2 of 4 (permalink) Old 2011-09-12, 05:53 AM
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Yeah, youll notice that the wider feed gaps give a bit better gain on the original version of the GH.

Theres also another big advantage from the build standpoint. The edge of a pvc tee, of the size commonly used in the construction of a GH, can be used as a holding stop edge for the GH element.

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post #3 of 4 (permalink) Old 2011-09-12, 01:08 PM
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Question Wide feed gap vs narrow feed gap?

Various DYI's on this forum use 2", 3", 4" feed gaps. The centipede used a 1" feed gap.and the multi-lobed Stealth Hawk uses a 2" feed gap.and the forward gained GH uses a 3" feed gap.

Question:
If wider feed gaps give a bit better gain,.. does that mean there is a narrower beam-width therefore producing better forward gain? If so, then a narrow feed gap would be best for someone who wants a wider beam-width.

3D SSH III with ZZ4 refl. http://imageshack.us/user/jmsdigital
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post #4 of 4 (permalink) Old 2011-09-12, 07:53 PM
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Quote:
Question:
If wider feed gaps give a bit better gain,.. does that mean there is a narrower beam-width therefore producing better forward gain? If so, then a narrow feed gap would be best for someone who wants a wider beam-width.
Yes, but over the 1 dbi difference in gain in the above linked graph, the change in beamwidth is only less than about 5 degrees, ie 2.5 degrees or less to each side.

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