Hi All,
I was going thru some of my old antenna design notes from the early '70s
and ran across some notes on my designs/results for some stacked 8 el. wide
spaced yagi's for VHF (2 mtrs mostly). During one of my brainstorms, I decided
to add a 2nd reflector (3% longer & spaced .2 wl behind the 1st) to the stacks,
just to see what would happen. The results looked pretty good but crude at
best, but it was something to try. (It must have worked somewhat, as I worked
Clearwater Fl. from NE Ma.on 2 CW with 10 watts.)
Not having any super test equipment, the results and plots were crude as my
only signal source was an FM repeater about 25 miles away and the S-meter on
my old TS-700s. My test site was a clear 300' hilltop with the stacks on a 15'
mast strapped to a picnic table about 50' from the van. I used a compass rose
for asimuth bearings and did circle plots of sig strength every 15 degrees.
When I was done, I just connected the dots. Pretty crude eh?
WISH I HAD SOME ANTENNA MODELING S/W BACK THEN!!!!
To get to the point.... Has anyone experimented with adding a 2nd reflector to
a yagi design? If so, how much longer than the first ref. was it? Spacing?
How did it enhance/degrade the F/B, fwd gain, beam width, side rejection etc?
Am I just blowing smoke?? Or is this a valid line of questioning to persue??
Thanks for the BW
73,
John K1RC
Dracut, Ma (on the COW-Hampshire border)
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|