Sum Ting Wong wrote:
On Mon, 18 Feb 2008 13:47:22 -0800 (PST), wrote:
There is a yahoo group devoted to skywire loop antennas and some good
info can be found there.
There is also an article on pg. 56 of the March 2008 QST on this
topic. The author used ferrite on the coax/power cable to the auto
tuner to isolate it an make it act as a balanced tuner. The loop in
the article was fed directly and not with a feedline from the tuner to
the loop.
S.T.W.
I once thought that would work, and even helped a little with an Antenna
Compendium article promoting it a long time ago. But I came to realize
that it doesn't matter at all whether the balun is at the input or
output of the tuner -- the balun is just as effective one place as the
other. The reason is that what counts is the common mode impedance,
which is the impedance to ground seen looking along the outside of the
coax toward the antenna, and this is the same on both sides of the tuner
(except, of course, for the difference due to the short distance between
the two points). Putting the balun the input has the disadvantage of
making the tuner chassis hot.
I'm sorry to see that QST's article review process still isn't working.
Roy Lewallen, W7EL