AV & DAVE,
FIRST: These are NOT Transmitting Antennas so the Metal
Fence does NOT represent a 'potential' Hazard to your
Transmitter. (Possible Direct Short Circuit to Ground.)
"AV" - It's Not the Fence...
Its the 200 Feet of Wire that makes up your Antenna Element.
NOTE: With Metal Fences "Insulated" Wire seems to work better
)
Two Points of View for 'shorter' (20Ft-50Ft) Insulated Wire
Antenna Elements that are mount "ON" or "THRU" Metal Fences:
* Some people may tell you to run/route the Insulated Wire
alone the "Top" of the Metal Fence.
The Reasoning Being: The Wire is Higher in the Air
and Off the Ground.
(The Metal Fence will have less effect on the RF Signals
being Received.)
* Other people may tell you to run/route the Insulated Wire
alone the "Middle" of the Metal Fence.
(Half-Way between the Top and Bottom of the Fence.)
The Reasoning Being: The Wire is in the Air and Off the Ground.
(The Wire is being 'coupled' to the Metal Fence and the "Whole"
Metal Fence has become the Antenna with a greater capture are
to Receive RF Signals.)
THIRD OPTION: "Above-the-Fence" Field SWL Antenna for a Field Radio.
Recently I had the need to build a 'temporary' Low Noise SWL
Antenna that was going to be 'mounted' ABOVE a Cyclone Fence.
NOTE: The Fence was down the Hill about 75 Feet from the Deck
of a Cabin. The Fence ran between a small Lake and a Cabin
overlooking the Lake.
* The Antenna Element was 100 Feet of Landscape Lighting Cable
(Heavy Duty Outdoors Zip Cord).
* The Fence was a Six Feet (6Ft) Tall Chain Line Fence.
* I walked-off the fence with a note book and pencil.
The Fence Sections (Poles) were 20 Ft apart.
* When down to the hardware store and bought Six 10 Ft
pieces of 1" PVC Pipe.
* Also bought some plastic Locking Wire Ties.
* Drilled a hole in one end of each of the PVC Pipes and
installed a Wire Tie with a 2"-3" Open Loop.
* Placed a piece of PVC Pipe next to each of the Metal
Fence Poles.
* * Attached a Guide Rope to the two end pieces of PVC Pipe.
* Ran/Routed the Antenna Element through the Open Wire Tie Loops.
* Affixed the two Feed-End wires of the Antenna Element
across a TV 300 Ohm Matching Transformer (MT) and connected
100Ft of 75 Ohm Coax Cable to the other end of the MT.
* * Attached a 12 Ft Ground Wire to the 75 Ohm Side of the MT.
* At the Far-End of the Antenna Element; stripped and twisted
together the two wires and covered them with electrical tape.
* Place the Far-End PVC Pipe in the Vertical Position and
used two Wire Ties to one at the Bottom of the fence and one
at the top of the fence to hold it in place. Plus used the
Guide Rope to Counter the Force of the Antenna Element.
* Next placed the four middle pieces of PVC Pipe in the
Vertical Position and used two Wire Ties to one at the Bottom
of the fence and one at the top of the fence to hold it in place.
* Then the Feed-End PVC Pipe in the Vertical Position and
used two Wire Ties to one at the Bottom of the fence and one
at the top of the fence to hold it in place. Plus used the
Guide Rope to Counter the Force of the Antenna Element.
* Attached the other end of the Ground Wire to the Metal
Fence Post with a Large Hose Clamp at ground level; at the
base of the Metal Fence Post and the in-the-ground Cement
Anchor (2Ft-3Ft).
* Ran/routed the Coax Cable from the the Antenna Element
to the Receivers location on a Deck. Used a second grounding
point directly under the deck at one of the Metal Pier Anchors.
* Terminate the Coax Cable with an "F" Connector to PL-259
Plug Adapter for connection to the Receivers LO-Z (50 Ohm)
SO-239 Jack. Or, use a second MT and Connect the 300 Ohm
Output Leads to the Receiver's HI-Z (500 Ohm) Terminals.
TBL: The Antenna Element is a "Flat-Thin-Loop" that is
Physically 100 Ft Long and Electrically 200 Ft Out-and-Back.
iane ~ RHF
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= = = AV
= = = wrote in message ...
Dave wrote:
It is a metal fence. Chain-link.
I didn't think that was a very likely answer to my problems.
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I'd be curious as to why running a wire along a metal fence would
be such a problem. I just ran about 200 feet of wire along the top
of a wire fence (2 inch square openings), albeit the type that is
covered with some green vinyl. And I have noticed CONSIDERABLE
improvement in reception. Wouldn't attaching to so much metal just
help to expand the range of the antenna ?
Also, related to the metal fence thing: what would happen were
I to attach a wire to my metal roof?
And as long as we're on the subject of random wire, what's the
deal with needing "stranded" wire. I had about 100 feet of that
first, and then when I went to buy some more all they had was
single strand, so I bought that and just added that to the end
of the stranded. what's the importance/need of using stranded?
av
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