REFLECTOR: nav antenna

[Steve Goldman]

So I'm hoping to finally glass my first wing surface tomorrow and I 
just finished installing the nav antenna. When I glassed my winglets a 
year ago I did't have an antenna analyzer. This year I happen to have 
borrowed one. I tested my comm antennas and they're ok, not tuned to 
the center of the band, but not bad. As I expected the comms ended a 
little long which would seem to be likely given the way they are 
constructed.

So I was surprised today when I measured the tuned freq. of the nav 
antenna and found the center is 122mhz. Although I have an EE degree 
I'll admit to not taking the transmission lines class so I'm no expert 
on antennas. A quick search of the net found a page that calculates 
dipole length and inverted V's like the nav appears to be. Giving that 
page the length of the leg (22- 13/16) shows that 122mhz is a 
reasonable center freq. Since the nav band is 108-118 a center of 113 
works out to a leg about 1-5/8 inches longer. So I made the antenna 
that length and tested it and it does center at 113.

So I'm wondering if anyone else has checked their antenna like this. 
Until tomorrow I'll stil have time to trim if what I'm doing is wrong 
even though it seems ok.

-- 
Steve Goldman