Mark Keith wrote:

Mark Keith wrote:

The easy way out for you, would be to get an existing 2m yagi, and
simply trim the elements. You could rescale in the model program to tell
you how much to take off.

BTW, if you rescale a 2m antenna, it will also rescale the spacing. So
in order to be accurate, you would need to respace the rescaled shorter
elements to match the old spacings. "After rescaling". Fairly
simple..That would give you a decent idea what to expect from the
modified antenna. MK

As a test I first rescaled the eznec 50 mhz NBS yagi to 146 mhz. I used
6-7-6 as the demo segment numbers. You are limited to 20 in the demo.
This kept the source in the middle of the DE..I ran it through the mill
and got 9.63 dbi gain, and 9.35 f/b. I then rescaled that antenna to 159
mhz. I then set the element spacings back to the 146mhz version specs.
Through the mill, and got 9.68 dbi gain, and 7.73 db f/b. About as I
expected...It would still be a good antenna. f/b is not much of an issue
for your needs in general...Thats more of an HF thing...You want gain
for local VHF. The chances of someone on your backside causing QRM are
fairly low... Find a 3-4-5 el 2m antenna, whack the elements down a tad,
and you'll be done with it. Well, unless you still wanna try building
one. It's easier to make a decent working yagi than you think, I
think...All that worrying about utter perfection will drive you to the
rubber room. :/ You would have to see about a 3 db difference in
performance to start really being noticable. Or my guess anyway on 159
mhz... MK
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