In article ,
"HankG" wrote:

"Telamon" wrote in message
..
.
In article .com,
"RHF" wrote:

JD,

Something Different - - -
On-the-Fence Loop Antenna for the Shortwave Listener (SWL)

You should first install an 8-Ft Ground Rod at the
Foot (Base) of the new Fence.
Note - This will be the Starting and Ending Point for
your Wire Antenna Element
+ The Mounting Place for your Matching Transformer
{ A Balun = Loop-to-Coax }
+ The Connecting Point for your Coax Cable.

Start by running the Wire Antenna Element out along
the Bottom of the Fence to your Far-Point.

Then a short Wire Antenna Element Leg-Up to the
Top of the Fence.

Next run the Wire Antenna Element back along
the Top of the Fence to your Starting-Point.

Finally a a short Wire Antenna Element Down-Leg
to the Bottom of the Fence.

Mount your Matching Transformer to the Ground Rod

Connect your Coax Cable to the Matching Transformer.

Connect your Two Wire Antenna Element Ends
to the Matching Transformer.

You now have an On-the-Fence Loop Antenna
[ Bent-Around-the-Fence ]

FWIW - Two On-the-Fence Loop Antennas
One Rigged on the Fence along one Side of the Yard
One Rigged on the Fence along the Back of the Yard
Set at 90 Degress and being about 8-ft apart at their
Starting Points from a common Corner can give you
more Receiving Antenna Options.
Note - Separate Ground Rods, Baluns and Coax Cable
Feed-in-Lines are recommended if you choose to use
two On-the-Fence Loop Antennas.

Interesting. I have a fence on 2 sides of my property. Previously, I ran a
longwire along the two sides (right angle). The end closer to my house was
fed directly to my second floor receiver (no transformer or coax). This was
used primarily for LW and MW, but served as a secondary antenna for HF
(primary is Cliff Donley's 33 foot folded dipole in my roof).

As to the Question of Antenna Wire Size :
# 14 AWG Insulated Copper Wire with 19-Strands
and using PVC Insulation is cost effective and durable.
HomeDepot type - THWN or THHN in 500 Foot Spools

TIP - One of the most important details of an On-the-Fence
Antenna is the Stand-Offs used to keep the Wire "OFF"
the Fence and in the Air. TV "Stand-Offs" with Plastic
Insulator Head and 3.5" Wood Screw base hardware.
RadioShack Catalog #15-853 (4 Pack)
http://www.radioshack.com/product/in...tId=2104003&cp

Other On-the-Fence Shortwave Listener (SWL) Antenna ideas

http://groups.google.com/group/rec.r...p=rec.radio.sh
or
twave&q=on-the-fence+rhf&qt_g=1


You describe a close to the ground vertical loop antenna. I expect that
at most you would need a 2:1 BALUN but the right answer might be 1:1
with the antenna that close to the ground. The loop is balanced and the
coax is not so a BALUN is used here.

The loop is a complete antenna unlike the single wire antenna, which
still needs a counter poise to complete an RF circuit. The counterpoise
or RF return for the signal wire is the ground stake. Generally an
optimal situation would be a voltage type transformer as a UNUN so the
single wire and ground would be the primary and the coax on the
secondary. The single wire is not balanced and neither is the coax so
UNUN is used.

The loop as a complete antenna does not need the ground as a
counterpoise. Useful construction tip would be to bury the coax or if
that is not convenient then use clamp on ferrite for a RF choke to stop
noise from the radio end of the coax on the outer shield from getting to
the loop antenna then into the radio input. The clamp on ferrite would
be a current type 1:1 BALUN.


I want to replace the flimsy longwire and the 'fence loop' looks promising.
Could you (the group) comment on the use of this setup for LW, MW, and HF
(each leg is about 85 feet long) with regard to the loops vertical
polarization, and whether bending the loop at the right-angle would add or
detract from its performance.

While you're pondering, how about a vertical 'conical loop'?

85 foot a side would be a 340 foot loop with a 1 wavelength of 2.95
MHz. When the loop receives at 1 wavelength and more than one
wavelength the receive pattern is in and out of the loop plane so a
horizontal loop would look straight up. Most DX signals tend toward the
horizon so this does not work as well. This type of antenna seems to
work better during the dark hours for me and not as good during the
daytime.

Conical verticals also tend to look up. These are used in the HARP
project to receive signals during tests. I don't know of anyone using
this type for SW listening. It would be interesting to try it.

--
Telamon
Ventura, California