Re: 2m/432 Antennas


montanaaardvark
 

On Wed, Jul 13, 2022 at 10:51 AM, Steve W3AHL wrote:
Avoid the Cushcraft VHF/UHF interlaced Yagi's, such as the A270-10.  They use a single feed point with a T-connector to drive both driven elements.  Since the 2M antenna is resonant as a 3/4 WL antenna at UHF, the UHF pattern is really messed up.  I worked with a local ham to add a VHF/UHF duplexor to isolate the two driven elements, but the gamma match tube for 2M DE was too short.  Lengthening it allowed it to tune, but the element spacicng really needed to be changed to get a decent pattern, which wasn't worth the effort.  He finally returned the antenna to MFJ for credit.

Steve, W3AHL
Thanks, Steve.  That's very valuable input. 

While I know the arrow beams and guys who have worked the satellites with one, my intent would be weak signal -- SSB, CW, FT8 or something like that.  Those are conventionally horizontally polarized, so the way Arrow has them 90 degrees apart would be less than optimum.

I looked up the Elk Antennas after Charles' post and while I'm replacing a log periodic, I'm leaning toward a Yagi, but that's as specific as I've gotten.  Something like 5 elements on each band sounds simple.  The Elk antenna I looked at doesn't even claim any gain or other specs, other than being a good match on both bands. 

I replaced my 6m LPDA with a Directive Systems Engineering 5 element yagi that I'm happy with, so I checked them first.  I didn't see any interlaced 2/432 antennas.


73,
Bob
--
W4ATM - 35 Miles south of the Kennedy Space Center
Retired RF Design Engineer
Now able to play with all the hobbies I never had enough time for

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