-=> Quoting Ivy Iverson to Ed Kriston <=-
 -=> On 11-23-97  08:21, Ed Kriston said to All,<=-
 -=>"About In Attic Dipole...,"<=-
-------------------------snip----------------------
 II> I'm sorry, but you aren't going to get an efficent antenna that's much
 II> less than 1/2 wavelength long.  OTOH, your attic only has 80 Ft. of
Ivy,    See if you can find a copy of the ARRL Antenna Handbook
somewhere there are a lot of techniques for making physically short
antennas resonant.  Inductive loading and capacity hats are just two
techniques.  They can be used separately or together on the same
antenna.  They will decrease the size of the antenna and the bandwidth
of the resonant frequency.
 II> "corner space," and the antenna is 105'?  Since you want to keep the
 II> ends as far apart as possible, I see two options: 1 is the foldback you
 II> are using, the other, which I would suggest trying, a zig-zag pattern
 II> like: ______________________________
 II> |       |~~~|   |~~~|   |~~~~||  This is a variation of an idea I read
 II> | ______|   |   |   |   |    ||  about some time ago - a Ham hid a
 Here, folding seems like a good idea, but the only thing it will do is
 fit the antenna into the space :-)  You will have field cancellation
 effects due to the folds and it would take a good computer program to
 guess at the resulting radiation patterns.
 ----------------------snip------------------------
 EK>  I have looked at just about every antenna design program
 EK> that I can find, none show how to do antennas with traps.  I figure
 EK> that my best approach to shorten the run is to use traps.  It won't be
 EK> outside in the weather, so it might not be a problem.
 
Ed,     Traps will electrically disconnect the middle of the antenna
from the ends of the antenna for the traps resonant frequency.  You
could have a multiband antenna with only one feed line.
 EK> ... I hope to modify the G5RV with traps and do away with the
 EK> ladder line part of it.
 II> You DON'T want to remove the ladder line!  That is part of the entire
 II> system design, and removing or shortening it will only degrade the
 II> system's performance.  If it wasn't needed, you can bet your last
 II> dollar it wouldn't be there.  Just make sure you keep it at least a few
 The ladder actually becomes part of the antenna on the lower bands.  If
 you delete it, you will  not be able to tune the lower bands anymore.
 II> inches from any signifigant amounts of metal, and especially don't run
 II> it through any pipe.  If you need to cut anything, cut the coax part.
 
 EK> BTW,  operating station is in the basement and there are two floors
 EK> of living area to the attic.  Hope to run shielded coax through the
 EK> living areas.
 -----------------------------snip-------------------------
 Ed,    You did not include the most important information when you
 start to talk about antennas.  What bands are you going to use and next
 to you want to point your signal in a particular direction?  In your
 case I would look into loop antennas.  You can look at some articles
 about cubical quads and just use the driven element from them.  It is
 possible to inductively load loop antennas to shorten them.  If you can
 find a copy of 73 magazine from October 1992 you will find a 40 meter
 square loop antenna that uses two loading coils in the sides of the
 loop resulting in a loop that is 52.34 feet around the outside of it.
 That is shorter than the 66 feet of the 40 meter dipole.  The 50-75 ohm
 coax is in the center of one side with the two coils in the next sides
 around the loop. The max radiation is towards the coax side of the
 loop.  You should also be able to load it on 10, 20, 17, 15, and
 12 meters. The coils are just part of the antenna wire wound on 2 inch
 pvc, 19 turns to cover 3 5/8 inches. If you have any questions let me
 know.
        Another option would be the "Army loop" made of a large
diameter tubing put into a loop and tuned with a capacitor and a motor.
Check the handbooks for details.  That would be best as you could mount
it vertically and rotate it, but to build it takes a lot more in the way
of resources.  It's what the commercial AEA Isoloop 10-30 antenna is
based on.
73, de Bob, W6TVJ, BSEE with over 30 years of hanging wires in the sky :-)
... A repeater lets more people hear you make an a** of yourself.  :-}
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