[amsat-bb] mode A loop ant

[w7lrd@xxxxxxxx (Robert V Johnson)]

Hello

I have received several inquires regarding a posting I made a few days
ago.  This goes back to an article in the May/June 1997 AMSAT Journal.
I'll briefly describe this antenna for those who may not have the
article.
It is simply a one wavelength loop (length in feet =1005/Fmhz), hanging
from a single support.  I use 1/2 inch sunlight resistant PVC pipe,  I
suppose any plastic pipe would work, but  the resistant pipe was
available at the local hardware store.  I glued all the pipe together put
the length of wire inside,  There is a PVC fitting where an SO239 can be
installed (if desired), or the coax can be soldered directly to the loop
ends.  I use RG8 coax feeding the loop, as that's what  I had (not
critical).   With the satellite approaching I use my terrestrial beam at
about 25-30 degrees I switch over to the loop for seamless reception.  I
have made side by side comparisons with the loop and a turnstile (crossed
dipole) antennas.  The loop is always as good as and usually better than
the turnstile.  It needs one support and might cost $10, less coax.  My
loop hangs about 20 feet off the ground.  I tried hanging a reflector 6
feet below the loop (length in feet= 1030/Fmhz).  Essentially a two
element quad looking up, I found the additional gain helpfull with RS-15.
 A wind storm blew the reflector away, and I haven't replaced it yet.  I
have found my terrestial beam ( 4 element quad)  "hears"  better off the
back at 29.5Mhz.  I'm guessing the first director is acting like a
reflector at 29.5Mhz, and the actual reflector is acting like just a
piece of nothing.  If someone with one of those antenna analyzing
programs would run this idea, I'd like to hear from them.  Any
questions/comments,e-mail direct.

Thanks for the bandwidth, see you on RS-13 or 15
73...Bob...W7LRD

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