[TowerTalk] Anyone using BIG LOG periodic antenns 50ft plus boom lengths?

[Denis Coolican]

At VE6FI we have a 3.7-30 mhz log periodic on a 70 foot boom.  I did
model this antenna and found that at any frequency there are usually
only 3 elements that are active. This would make it equivalent to a 3
element beam.

It looks massive and impressive but the impressive part is that it
covers such a wide frequency range at a SWR of 2.0:1 or better.  A 5
element monobander will  out perform the log every time.

When you dealing with such a large structure the rotator is usually the
critical component.  Most rotators are not designed properly and in our
case the rotator turns at 2 rpm which is much too fast.  With the large
amount of rotating mass, this antenna should rotate at 1/4 rpm and
should have a brake that mechanically locks the antenna when the antenna
is not being used. (between contests)

Denis Ve6AQ



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