John Smith wrote:

Jeff Liebermann wrote:

...
I also noticed that he cut his elements to a precision of 0.1mm. That
would be correct if the boom were an insulator or the elements were
inserted in insulating sleeves. However, since the 10mm square boom
is metal and effectively "shorts" part of each element, the actual
element length includes part of the diameter of the boom, thus adding
approximately 5mm to each element length (not including the reflector
and driven element). A VSWR sweep test would have shown the problem.


I have always used #8 wire as a boom on ghz yagis' (constructed a 7
element once.) Since the boom is at a current antinode (voltage node),
I ignored the boom.

The boom you mention is rather LARGE, give the freqs in question.

One of my next projects is a GOOD VSWR meter for ghz ... unfortuantly,
on the list of priorities here, it is low on the list ... :-(

What about surplus directional couplers and a bolometer set (various
military versions used to be quite affordable)? Used to show up at
hamfests regularly too, covered 1 to 20 GHz or so in the kit; sorry
I forget the AN number at the moment, but it came with half a dozen
directional couplers for the various bands and lots of adapters.

Michael