connents on hidden antenna's

---------

From: Fred Moore (fmoor@magicnet.net)
Date: Tue Sep 19 1995 - 20:13:30 EDT


It has been my experience that random wires that are less than several wave
lengths long (antenna's shorter than that are not really long wires). are
less efficient than dipole antenna's. This brings back the days of living
in appartments 18 years ago.

Let me describe the appartment it was a 4 family unit all in line, I was
lucky enough to have the only attic access, and was able to place dipoles
there. They seemed to work well. Other antennas were also a success. One
night I climbed to the roof, with a battery drill and a pocket full of sheet
metel screws, the screws were used to bond all connections of the gutter...
After attaching a wire to one of the down spouts and a counterpoise for each
band, I had a very well behaved antenna on all bands, many dx stations were
worked. lucky for me the shack was in the basement, I added a ground by
drilling a 1/2 inch hold in the morter between the blocks, and drove
(horizontally) a 40 foot ground rod, testing indicated that I had a 3.5 ohm
ground, It was used along with the counterpoises DX increased.

Next came the hidden beam. Using 22 ga magnet wire a beam was constructed
on the roof using clear RTV to glue the ends and centers to the shingles.
The wires were placed over the peak of the roof using the same spacing that
the handbook called for a optimum spaced antennas. A hole was drilled
(sealed afterward) placing the feedline at the driven director. The whole
setup resembled a 5 element beam that had the droups as the ends were about
35 degrees down. A small amount of pruning was required to get the SWR to
1:1 but it was successful. Fortunately the appartment was east-west..

Another antenna was a vertical (22ga magnet wire) that ran (RTVed) in
between the brick facing the whole pattern looked like kids blocks on end.
I was able to resonate the little gem as a 40 meter quarter wave. As I
recall the whole thing ended much shorter than expected. Don't know if it
was dialectic loading of the brick or reaction from running the wire back
and forth between the bricks.

My suggestion is to grabe a good antenna analyzer or a noise bridge, a
theory book and go to work....

I really enjoy monitoring this group, and the Arganut 509 is now working
wonderfull.....
------------------------------------
My words are my own and copyrighted.
------------------------------------
Fred Moore (ARS: WD8KNI) E-Mail: fmoor@magicnet.net
Work: Phone: (407) 678-7233
       Central Florida Safe & Lock ESD, Inc
       2070 Forsyth Rd
       Orlando, Fl 32807
Home: 2118 Allspice Ave.
       Orlando, Fl 32837


Search QRP-L Archives

[ QRP-L Archive | ]
[ 1993 | 1994 | 1995 | 1996 | 1997 | 1998 | 1999 | 2000 ]

---------

This archive was generated by hypermail 2b29 on Fri Jun 02 2000 - 11:28:32 EDT

kd4ab@kd4ab.org