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Old Feb 09, 2011, 02:41 PM
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United States, NC, Charlotte
Joined May 2009
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Originally Posted by IBCrazy View Post
Method 5 - IBCrazy's tapered match
Advantage - Provides the best match and maintains the antenna integrity. Also tolerant of manufacturing errors.
Disadvantage: Hardest to make.

I came up with this one experimenting with my directional Wattmeter. It has been the best method for me. You simply make a metal strip that is tapered so that the width is equal to the height over the reflector and follow the normal helix winding.

Width at wide point in inches = 700/f in MHz
Width at starting point - Sharp pointed.

Use this as the first 1/4 turn of your helix making it follow the natural helix winding spacing. The shape keeps the signal from being attenuated and also allows for some manufacturing error. This match is not supported by any reference I know of. It is something I made up by a tapered transmission line calculation and empirical measurement.
Is this the new one that I should try? I dont remember seeing it before. Also, does it run parallel to the existing copper helix, or do you trim the copper away so it begins where the tapered match ends?
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