Wrapped Antenna Feeding
 

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

--
73 for now
Buck, N4PGW

www.lumpuckeroo.com

"Small - broadband - efficient: pick any two."

Wrapped Antenna Feeding
 

"Buck" wrote in message
...

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

--
73 for now
Buck, N4PGW

www.lumpuckeroo.com

"Small - broadband - efficient: pick any two."

results will be bad, better than a dummy load but not by much. google for
ctha and stop listening to art.

http://www.antennex.com/preview/Folder03/Nov5/ctha.htm
http://www.cira.wvu.edu/index.php?/m.../projects/ctha
http://ieeexplore.ieee.org/Xplore/lo...rnumber=569433

Wrapped Antenna Feeding
 

On 22 mar, 10:46, Buck wrote:
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

--
73 for now
Buck, N4PGW

www.lumpuckeroo.com

"Small - broadband - efficient: pick any two."

Hello Buck,

Assuming real world materials are used:

Both AB, ab (situations 1 and 2) whether shorted or not will be a
very, very bad radiator (you made a twisted pair as distance between
wires Wave Length). It is an electrically small structure; you
don't get end-fire (upwards) radiation.

Your situation 3 depends on the routing of the return wire, so this
one cannot be answered

Situation 4 will radiate as a loop (assuming symmetrical feed so that
feed line does not contribute to radiation).

Best will be connect ab and feed over ground or counterpoise (running
horizontally or downwards).

Best regards,

Wim
PA3DJS
www.tetech.nl
remove abc from the mail address.

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