I want to erect a full-wave horizontal loop antenna for use around 3.5
mHz (as an NVIS antenna). The problem is, I don't have quite the
space to configure such an antenna, which would be somewhere around
280 feet long using normal wire. (Don't have my actual calculations in
front of me, but they are roughly these dimensions).

I've gotten the idea that I could shorten the physical requirement, by
using RG-58 coaxial cable instead of regular wire, and taking the .66
velocity factor into account--- turning an electrical length of about
280 feet into only around 180 physical feet of RG-58. (I have a 1000-
ft reel of this stuff). It would be fed with 300 ohm parallel lines
to an antenna tuner.

The questions, to those who may be more well-versed in the theory of
antennas, are 1) is my reasoning on the V.F. sound? and 2) if I
construct this, should I use the center conducter of the cable as the
active element, or the shield, or connect them together? and 3) Would
the shielding on the cable have any effect on the center conductor
being used as the antenna element?

JP

"John Poet" wrote in message
...
I want to erect a full-wave horizontal loop antenna for use around 3.5
mHz (as an NVIS antenna). The problem is, I don't have quite the
space to configure such an antenna, which would be somewhere around
280 feet long using normal wire. (Don't have my actual calculations in
front of me, but they are roughly these dimensions).

I've gotten the idea that I could shorten the physical requirement, by
using RG-58 coaxial cable instead of regular wire, and taking the .66
velocity factor into account--- turning an electrical length of about
280 feet into only around 180 physical feet of RG-58. (I have a 1000-
ft reel of this stuff). It would be fed with 300 ohm parallel lines
to an antenna tuner.

The questions, to those who may be more well-versed in the theory of
antennas, are 1) is my reasoning on the V.F. sound? and 2) if I
construct this, should I use the center conducter of the cable as the
active element, or the shield, or connect them together? and 3) Would
the shielding on the cable have any effect on the center conductor
being used as the antenna element?

JP

1. no
2. you could use the shield or connect them together.
3. yes, it would make it not work worth beans.

the velocity factor only applies inside the coax, you can't use that to
shorten the antenna.

John Poet wrote:
I've gotten the idea that I could shorten the physical requirement, by
using RG-58 coaxial cable instead of regular wire, and taking the .66
velocity factor into account---

The velocity factor applies to differential transmission
line currents, not to antenna currents which are common-
mode. Instead, it sounds like you need a loading coil
opposite the feedpoint.
--
73, Cecil http://www.w5dxp.com

Forget about coax. too expensive, too heavy even if it would work.
With Loops you can zig zig in and out to get all the wire up it does
not need to be in a square etc. Just get it all up and it will work.
Why not a dipole which also can be bent. Try to avoil loading coils
if at all possible.
john w9zy

vvvvvvvvvvvvvvvvvvvvvvvvvv w9zy

commander john wrote:
With Loops you can zig zig in and out to get all the wire up it does
not need to be in a square etc.

A series stub of ladder-line works well to shorten the
length of a loop.
--
73, Cecil http://www.w5dxp.com

commander john wrote:
Forget about coax. too expensive, too heavy even if it would work.
True !
Use simple wire for example horisontal quad or
make bi-quad for 80m like this one:
http://ham2.cc.fer.hr/9a3li/

/\/\
\/\/

Cecil Moore wrote:

With Loops you can zig zig in and out to get all the wire up it does
not need to be in a square etc.

A series stub of ladder-line works well to shorten the
length of a loop.

Another way of getting a loop antenna for 80m for reduced place is
switching two 40m delta loops in serie.

This website is in German language shows some drawings with a 41 feet
mast in the middle and four 10 feet supports in square.
It was published in a standard antenna book in Germany from Karl
Rothammel, DM2ABK.

http://www.technik.ba-ravensburg.de/...htpyramide.htm

"The WBØAOF 80 meter pyramid antenna" may be known in the USA.

http://f6arc.free.fr/pages/12_1.html

do they really think someone is going to take the time to un-mung the
addresses below just to get to a site that is probably full of viruses???

"nsk" wrote in message
...

*O-K-.-.-*-*-w---w---w---.---9---n---s---k---.---c---n---.---*-'-n-t-n-'-
-(-h-t-t-p-:-/-/-w-w-w-.-9-n-s-k-.-c-n-/-)- -'-S-K-F-'-
-(-h-t-t-p-:-/-/-w-w-w-.-9-n-s-k-.-c-n-/-)- -'-F-A-G-'-
-(-h-t-t-p-:-/-/-w-w-w-.-9-n-s-k-.-c-n-/-)- -'-N-S-K-'-
-(-h-t-t-p-:-/-/-w-w-w-.-9-n-s-k-.-c-n-/-)- -'-t-i-m-k-e-n-'-
-(-h-t-t-p-:-/-/-w-w-w-.-9-n-s-k-.-c-n-/-)-[-i-m-a-g-e-:-
-h-t-t-p-:-/-/-w-w-w-.-t-j-n-r-z-c-.-c-n-/-i-m-a-g-e-s-/-h-t-t-p-_-i-m-g-l-o-a-d-.-g-i-f-]-




--
nsk

Dave wrote:
do they really think someone is going to take the time to un-mung the
addresses below just to get to a site that is probably full of viruses???


SKF, FAG and NSK are well known Ball Bearing manufacturer, so there must
be some chinese copy products !

Darko_SWL wrote:

SKF, FAG and NSK are well known Ball Bearing manufacturer...

FAG makes ball bearings?
Are they permanantly lubricated?
Or do you need a tube of FAG lube
to re-pack them from time to time?


Lumpy

How come you didn't star on Star Trek?
Because Clint Howard beat me for the part of Balok.

www.LumpyVoice.org