What kind of 1/2 wave antenna is this?
 

Way back in the good old days, I had a situation where I couldn't
center-feed an antenna, and couldn't use any kind of end-fed antenna that
required a ground system. So, I built an antenna that's described below.

1/4 wavelength of wire going to two egg insulators. Off of one of the egg
insulators is another 1/4 wavelength of rope. The feedline (coax) is
taped to the rope along its length, then the rope and feedline combination
is enclosed in 1/4 wavelength of copper braid. The center conductor of
the feedline goes to the wire, and the shield goes to the braid.

This then becomes for all practical purposes a 1/2 wavelength end-fed,
which is actually a center-fed because that's where the coax center
conductor is actually connected. Unlike a traditional center-fed dipole,
you don't need to worry about running the coax away at right angles for a
certain distance.

I seem to recall that this antenna worked pretty well on 20 meters but I
really had nothing to compare it with, and I only ran 50 watts anyway so
didn't get much DX.

I vaguely recall this antenna being referred to as a "bazooka" but I have
since seen the term "bazooka" applied to something else (e.g.
http://www.hamuniverse.com/bazooka.html), and mostly all I see is
references to a "double bazooka" (is there a single bazooka?).

Does this ring any bells with any of you?

Where can I buy braid that will be suitable? Most braid I've seen is flat
and if it can be rounded out at all (so that things can be inserted inside
the braid), doing so over a 1/4 wavelength on 40 or 20 would be very
difficult.

Thanks...

What kind of 1/2 wave antenna is this?
 

Rick wrote:
1/4 wavelength of wire going to two egg insulators. Off of one of the egg
insulators is another 1/4 wavelength of rope. The feedline (coax) is
taped to the rope along its length, then the rope and feedline combination
is enclosed in 1/4 wavelength of copper braid. The center conductor of
the feedline goes to the wire, and the shield goes to the braid.

This is the old coaxial vertical antenna just bent at
the center.
--
73, Cecil http://www.w5dxp.com

What kind of 1/2 wave antenna is this?
 

On Mon, 09 Apr 2007 17:21:11 +0000, Cecil Moore wrote:

This is the old coaxial vertical antenna just bent at
the center.

OK, except that it wouldn't be bent at the center... the 1/4 wave of wire
and the 1/4 wave of rope / coax / braid would all be horizontal.

What kind of 1/2 wave antenna is this?
 

Rick wrote:
On Mon, 09 Apr 2007 17:21:11 +0000, Cecil Moore wrote:

This is the old coaxial vertical antenna just bent at
the center.

OK, except that it wouldn't be bent at the center... the 1/4 wave of wire
and the 1/4 wave of rope / coax / braid would all be horizontal.

Sorry, from your description, it sounded to me
like the rope was going off at a right angle.
--
73, Cecil http://www.w5dxp.com

What kind of 1/2 wave antenna is this?
 

Rick wrote:

1/4 wavelength of wire going to two egg insulators. Off of one of the egg
insulators is another 1/4 wavelength of rope. The feedline (coax) is
taped to the rope along its length, then the rope and feedline combination
is enclosed in 1/4 wavelength of copper braid. The center conductor of
the feedline goes to the wire, and the shield goes to the braid.


Andy comments:
I remember seeing something similar where a coax feedline had
the center conductor connected to 1/4 wavelength of wire, and
then 1/4 wavelength down the coax feedline, the coax was wrapped
thru a
toriod, which decoupled the "outer surface" but didn't affect the
inner power flow which was common mode..... Seems to me that it would
work the same
way.....
Anybody seen this, or have a name for it ?

Andy W4OAH

What kind of 1/2 wave antenna is this?
 

"Rick" wrote in message
...

Way back in the good old days, I had a situation where I couldn't
center-feed an antenna, and couldn't use any kind of end-fed antenna that
required a ground system. So, I built an antenna that's described below.

1/4 wavelength of wire going to two egg insulators. Off of one of the egg
insulators is another 1/4 wavelength of rope. The feedline (coax) is
taped to the rope along its length, then the rope and feedline combination
is enclosed in 1/4 wavelength of copper braid. The center conductor of
the feedline goes to the wire, and the shield goes to the braid.

I think you are describing a sleeve antenna. Usually hung vertically. It is
described in either the ARRL Antenna Book, or the Handbook.

Tam/WB2TT

What kind of 1/2 wave antenna is this?
 

"AndyS" wrote in message
ups.com...

Rick wrote:

1/4 wavelength of wire going to two egg insulators. Off of one of the
egg
insulators is another 1/4 wavelength of rope. The feedline (coax) is
taped to the rope along its length, then the rope and feedline
combination
is enclosed in 1/4 wavelength of copper braid. The center conductor of
the feedline goes to the wire, and the shield goes to the braid.


Andy comments:
I remember seeing something similar where a coax feedline had
the center conductor connected to 1/4 wavelength of wire, and
then 1/4 wavelength down the coax feedline, the coax was wrapped
thru a
toriod, which decoupled the "outer surface" but didn't affect the
inner power flow which was common mode..... Seems to me that it would
work the same
way.....
Anybody seen this, or have a name for it ?

Andy W4OAH

No, but very interesting. I was going to try this, to see if it would work.
Should be able to use a 1:1 commercial current balun at the point 1/4 wave
down the coax. I think you do not take the coax propagation velocity int
account. There is also triaxial cable.

Tam/WB2TT