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Old Jan 25, 2011, 09:28 AM
cmccracken is offline
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K0RSQ
Saint Louis, Missouri, US
Joined Sep 2010
139 Posts
Wow Alex, great work! I hate to be the whiny guy, but could you post more/better pics of the #3 & #4 impedance matches (microstrip & conductor), especially how they are installed on the antenna? The Hecker transformer (I never knew it was called that) has been the only impedance match I've ever seen on a home-made helical before, so I'm really curious about these alternate methods. What exactly are you referring to as "height" in the calculations?

What do you think is the best material to use for the support brace? I have access to CNC-cut G10/FR4, but it looks like it has a significant dielectric constant and even adjusted for it there is ~>3dBi loss in gain. I'd like to use something CNC-cut, as the notches could be accurate to within a few hundredths of an inch. Maybe hobby plywood? Do you happen to know if adding a water-resistant coating like Thompson's WaterSeal will change the dielectric properties? Google had no love for me on that one.
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