Posted: 4/14/2011 8:06:08 AM EDT
Anyone ever messed with an antenna like this?
 
I'm wondering if there's any way to model the efficiency trade-off between making the vertical shorter and the cap hat legs longer. Any help appreciated, thanks! |
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I'm in the process of .v.e.r.y . . s.l.o.w.l.y. building the W9SR "Top-Loaded Low-Band Antenna" from the ARRL 2007 Handbook (pp 22.27 - 28). Got the hub done for the capacitance hat so far and I'm actively working on getting the materials to build the loading coil now. Yesterday, I found the blog of a guy who is also building the same antenna (first post here, second post here, third post here). I've not yet found anyone who has completed one.
[Edit: I should have included some details for those who don't have the book: This antenna has a 6" loading coil on a nonconductive form atop a 10' section of TV mast. Above the coil is a 2-1/2 foot section of 1.25" OD aluminum tubing that holds the capacitance hat. It has 6 radials of 3/16" aluminum rod, 4.5' long each. Specs are given for coils to work on 160, 80 and 40. It needs a match where it's fed at the base.] I'm hoping to have it completed in time to work the bugs out and use it for Field Day. Here's my hub. My lathe is a bench top piece of crap, so I did the hub on the mill with a rotary table. It weighs 9.8 oz, not counting the 6 radials or the stainless guy rings shown (which really aren't necessary the way I drilled the hub). 
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Quoted:
Will do. Will CocoaNEC not allow you to tweak the design and do what-if comparisons for efficiency? I'm struggling to figure out EZNEC, so I really wouldn't know. It probably does, but I'm still struggling with it too. Plain and simple, I just don't know what I'm doing yet when it comes do modeling antennas. |
| Don't know if this will help, but stumbled over it and remembered this post. |