Re: [IRCA] PARAN antennas (was: Synchros, anyone?)

[AM-DXer@xxxxxxxxx (Patrick Griffith, N0NNK / WPE9HVW)]

Dan, information on the Paran antenna is indeed rare. There are some
photos of the KAPS Paran antenna on my AM-DXer web site (see link
below). Note that the FCC lists this array as DA-2, not ND. However, the
field plot appears to show it as non-directional. I suspect that the
DA-2 designation is an anomoly caused by the fact that there are 4
towers involved. Possibly either the FCC computer, or the person
entering the data, presumed that 4 towers must be a directional array.

I don't think the Paran antenna has much to do with the NIMBY situation.
Although the towers are relatively short for a 660 array, as you will
see from my KAPS photos, there is still plenty of steel in the sky. I
think the Paran had more to do with the reduction of low angle sky-wave
radiation resulting in an "anti-skip" antenna. In the case of KAPS I
have been told that they were originally trying to create a degree of
protection to a station in Calgary while still providing a
non-directional pattern in their primary coverage area.

If my understanding of the Paran is correct, I picture the night-time
characteristics as being similar to that of the Near Vertical Incidence
Skywave (NVIS) antenna used mostly by the military for medium range HF
operations. In NVIS the antenna is horizontally polarized and located a
relatively small percentage of the wavelength above the ground. The
skywave portion of the radiated signal goes almost straight up. Since it
strikes the ionosphere at a near vertical angle it is mostly reflected
straight back down. If you could visualize the reflection from the
ionosphere it would look something like an umbrella. This provides good
short to medium range coverage but reduced long range coverage. 

I don't know the current status of KIPA but the data for the 3-site
synchro system is still in the FCC database. The FCC lists the primary
site as Hilo with 5 kw and a standard antenna. It lists the synchro at
Kalaoa with 10 kw and a Paran antenna with 4 towers. And it lists the
synchro at Naalehu as 5 kw with a Paran antenna but only 1 tower with
top-loading. 

Here's a thought. A lot of AM stations use top-loading to increase the
electrical length of the antenna without increasing the physical height.
Many use part of the top set of guy wires as the top loading element.
For many years Rockwell-Collins has produced an HF NVIS antenna called
the orthogonal antenna. It consists of 2 crossed sloping dipoles
connected to each other at the elevated center feed point. The outer end
of each dipole slopes down to the ground and also serves as a guy wire
to support the antenna. The center support is actually the feedline and
the RF is coupled to the antenna at the base of the center support. It
looks very much like a miniature version of a top-loaded AM tower. I
wonder if they were trying to accomplish a MW variant of that design
with the KIPA Naalehu synchro antenna? That might explain why the FCC
calls it a Paran but it only has 1 top loaded tower.

Patrick Griffith, Westminster CO
http://community.webtv.net/N0NNK/
http://community.webtv.net/AM-DXer/

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