In reading the Jan 2007 issue of 'QST' I came across the article, "17 Meter
Wonder Bar Antenna". This antenna appeals to me due to the fact of low wind
resistance, the ability to use a TV rotor to turn it, and I have all the
materials for construction. However, the article left me with a number of
1. No formulae were given to scale the antenna up or down to suit other
bands. I have built a number of yagi antennas and I generally understand how
to formulate changes for given bands. However, this antenna has shortened
elements, in a bow-tie configuration, and therefore I do not have a clue how to
figure the boom spacing of the elements, size of the elements, or the coil size
required. I would like to understand how to compute dimensions for shortened
2. This particular antenna uses coils wound on 1" ID PVC. Would an air wound
coil be more efficient or have an advantage over this design?
3. The author capacitive couples the feed line to the coil of the driven
element. Is there a more efficient or solid means of connection? Would anyone
have a guess as to the power handling capability of such a setup?
4. Tuning the coils to make the elements resonant left me a little fuzzy. If
I construct the coil / element assembly how do I properly attach my MFJ-259
(Pre B Version with only the PL-259 connection) to the coil? Does a reading of
the lowest SWR actually indicate resonance? I also have a grid dip meter if
this would provide a more useful measurement of resonance.
I fully understand that this antenna is not the most efficient design that I
could use. However, for the reasons stated above, it definitely would work
well in my location. This will all become a moot point when my 80? tower is
erected, but until such time, this should provide me with a decent antenna at
little or no cost.
Thanks for your assistance,
Doug Coffman ? N9XTF
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