Jim,
I have also tried several horizontal and vertical combinations (everything
you mentioned except a quad loop) on 30 meters. After lots of very
unscientific experimentation and observation, I ended up with: A multi-band
vertical (Hy-gain AV-640) which I use as my 'reference' antenna, and a
horizontal delta loop at about 40 feet. I find the delta loop quieter than a
previous dipole or the AV-640 vertical; it has a flatter SWR curve (although
that doesn't seem to matter much on the narrow frequency allocation on 30
meters); and gives me better DX signal reception _almost_ all the time (once
in a while the vertical beats the loop, but it's rare). The delta loop's
characteristic impedance is 100 ohms, and I feed it in the corner with a 1/4
wavelength of RG/6 as a matching balun. Although the calculated length of
the loop should be 97.14 feet (frequ/983), I found that the best resonance
occurs when the total wire length is closer to 103 feet (lesson: you can
always cut it shorter, but can't cut it longer).
--
-larry
K8UT
"Jim Leder" wrote in message
...
I have modeled a 30 meter dipole, a Delta loop and a Quad loop (the loops
'hung' in a vertical plane). I have also spent hours reading various posts
and web articles on the 2 loop antennas. I am trying to better my
situation on 30 meters, my favorite band. Currently I have a dipole at
about 38 feet, which is as high as I can go with the top wire and the
trees that I use are no more than 48 feet apart (the dipole fits
comfortably). I also have a wire vertical with 16 radials which gets
dismantled when grass cutting season starts, it probably will go back up
next fall. According to EZNEC, the Quad loop is a little better than the
Delta loop which is a bit better than the dipole, but not by much. I did
try a half square, and it seemed to work well on transmit, but it was as
noisy as the vertical on receive. The dipole is nice and quite on receive,
as it should be. The HS lasted 3 days before the dipole went back up.
I've never used either loop but I did at one time use the inverted L loop.
It worked OK, but was also noisy on receive and I probably lost an S unit
due to low gain. The dipole seems to be the best antenna I've tried under
my circumstances so far, but I sure would like some opinions on the 2
mentioned loops: Is either noticeable better than a dipole? Which one and
why? Are both nosier (important) than a dipole ( both vertical hung,bottom
fed apex down on the Delta loop and the Quad loop fed in the center of the
bottom wire)? Should I just stick with the dipole and spend my efforts
elsewhere? With the 48 feet between trees and my maximum height of 38
feet, is there anything better I could try?
I KNOW what the modeling programs say, but I don't always believe them
and I am looking for PRACTICAL experience and personal opinions on the
above 3 antennas. As it sits, I'm inclined to let well enough alone and
stick with the simple dipole, unless I can be convinced otherwise.
Thanks...
--
***** Jim Leder *****
IBM retiree since 1999
http://home.fuse.net/k8cxm