View Single Post
  #4   Report Post  
Old March 30th 08, 12:48 AM posted to rec.radio.amateur.antenna
Dave Oldridge Dave Oldridge is offline
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 234
Default Wrapped Antenna Feeding

Buck wrote in
:


A B
\ /
X
/ \
\ /
X
/ \
\ /
X
/ \
\ /
X
/ \
a b

The above diagram represents a piece of material with two wires
wrapped around it. One is wrapped clockwise and the other is counter
clockwise. The first wire is a to A and the second is b to B.

For the sake of discussion I am going to assume the piece of material
is a 1" diameter pvc pipe and the wire lengths are each 16 feet or the
equivalent of a 1/4 wave for 20 meters.

I realize that the inductance will create a variation, but since this
is hypothetical, I am assuming this is a 20 meter antenna. Also
assume it is 20 feet or more above the ground with no ground plane
radials.

There are several scenarios for feeding this antenna. My question is
what kind of performance could I expect by each of the variations
below?

1) Feed ab - This is like a dipole with the elements intertwined.

2) Short AB and feed ab - a closed loop

3) feed Ab - this would require additional wire to reach the ends

4) feed Ab - using bending the pvc like a hula loop.

Thank you


Short A to B and short a to b. Supply radials and feed at one end
against the radials. Work 20m DX.





--
Dave Oldridge+
ICQ 1800667