Antenna

[K7LXC@aol.com]

In a message dated 96-12-02 23:57:17 EST, you write:

>	Hope you don't mind that I intercepted your message.  I currently have a
>TH5-MK2 at 48 feet and a KLM 40-M1 Dipole at 56 feet.  I have been
>considering the C-4XL as a replacement for the two antennas but was unsure
of
>how the Force-12 would perform since it is only a 2 element (driven,
>reflector)  antenna compared to the TH5 which has a director, reflector and
2
>driven elements for each band.

Hi, Jim --

     The important concept to keep in mind is that gain is directly
proportional to boom length; the longer the boom, the more gain.  So for two
antennas of similar boomlength, they'll have similar gain.  The TH5 is 19
feet and the C-3 18 feet (C-4XL is 30 feet) but the additional boom over the
18 feet is for the second 40M element so I would expect the two antennas to
be very similar in terms of gain. (We're forgetting about trap loss, etc. for
a minute.)  The advantage of the C-4XL, of course, is that you get 2 elements
on 40 plus 12 and 17M usefullness.  

      The TH5 was designed by trial and error about 25-30 years ago.  The
Force 12 antennas have been extensively computer modelled and optimized using
unique design properties and tools that are currently available.  While the
jury is still out in the longterm on-the-air results for Force 12 antennas, I
suspect that at the worst they are as good as any other well-performing
antenna and better than some (Mosley, etc.).

>	I would appreciate any input you would have.  Also, you mentioned a paper
>you wrote on "Building a One Tower Station."  Would you mind sending me a
>copy?
>
     It's winging its way to you.

73,  Steve  K7LXC

   TOWER TECH -- professional tower supplies and services for amateurs



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