J_Pole Trials and Tribulations
 

J_Pole Trials and Tribulations
 

wrote:

I happen to like them as they can be made from common materials with
excellent ruggedness.

A 1/4WL ground plane takes one SO-239 and five pieces of
19 inch copper wire (or stingers). :-)
--
73, Cecil http://www.qsl.net/w5dxp

J_Pole Trials and Tribulations
 

Roy Lewallen wrote:
What's the mechanism which gives this half wave antenna 2.4 dB gain over
a half wave dipole?

A J-Pole over ground obviously has gain over a half wave
dipole in free space? :-)
--
73, Cecil http://www.qsl.net/w5dxp

J_Pole Trials and Tribulations
 

wrote:

Cecil Moore wrote:
A 1/4WL ground plane takes one SO-239 and five pieces of
19 inch copper wire (or stingers). :-)

Now drive over one with a Chevy Pickup, the Jpole survived that
at field day one year.

Well, I just did that with a GMC pickup (hope that counts).
Nothing broke. I just straightened out the wires and it
still works just fine. If, Heaven forbid, a wire broke, it
would only take a butt connector and 20 seconds to repair it.
--
73, Cecil http://www.qsl.net/w5dxp

J_Pole Trials and Tribulations
 

Same here..in the attic...works great...even at 50w.

73 de KB9BVN


--
=========================================
Radio Amateurs - Fill your junk box, from my junkbox!
http://www.hamradparts.com
73 de KB9BVN
=========================================


"Buck" wrote in message
...
On 25 Apr 2006 16:43:11 -0700, wrote:


jimbo wrote:
SNIP
jimbo - AJ7IM

Hi Jimbo, it has been my experience, and everybody else's that an
indoor or attic J-pole is unpredictable. A high impedance end fed
antenna in an attic environment will be hard to predict. Moving it one
foot can effect things.
You might consider the SO-239 ground plane. It can be built and
tuned in 30 minutes, is 50 ohms, so it will not be so concerned about
its environment. Likely you could not tell a difference in performance
from a J-pole especially if they are both in the attic.
Oh yes, the standard-if the SWR is below 3.0, don't worry about it.
Gary N4AST


I started building dipole antennas. they can be mounted horizontal or
vertical and easily moved around. I use cpvc with a dipole wire
inside and a coax-choke balun. They work quite well.

Just another option.
--
73 for now
Buck
N4PGW

J_Pole Trials and Tribulations
 

J_Pole Trials and Tribulations
 

Bob wrote:
snip

My point is, why not make a simple ground plane for the attic that may
not get bothered by surroundings as much as the J-pole.
Bob


I made one of those antennas right after I got my Tech license. Hit
the local repeater with no problems. I guess I forgot or thought it
was too simple for the current application.

jimbo

J_Pole Trials and Tribulations
 

"Bob" wrote in message
. com...
The J-pole crowd seems to tout fantastic claims about this antenna and I
have never been impressed. Many people have tested the J-pole against
other easy to make antennas and the end fed half wave J-pole usually
does not stand up to even it’s brother, the center fed half wave dipole.
I assume the decrease in performance is due to mistakes in assembling
and tuning the matching section. Here is a link to a group that tested
some J-poles against other antennas in the CA desert and the J-pole lost
to even simple 1/4 wave ground plane types.
http://www.geocities.com/SiliconVall...5/anttest.html

snip

A quick look at the numbers doesn't make the j-pole look so all-fired bad.
"Losing" by 1 dB or so isn't a serious loss. Ham radio isn't exactly the
Kentucky Derby.

I don't know what "fantastic claims" you've heard, but my affinity for the
j-pole comes from its simplicity and durability. It's a halfwave vertical
that requires no ground plane and can often be matched to 1:1 at the sweet
spot. Mounting is a dream -- it even works if you drop the low end into a
plumbing vent pipe. (How would I know that? ;-)

I have never built a center-fed halfwave, but we use a bunch of them in the
Navy -- call them "stovepipes" because of the way the fiberglass housings
look -- and they work very, very well. The elements are large metal
cylinders, tending to make them quite broadband. I do not know how they're
fed ... balun or what.

John , KD6VKW

J_Pole Trials and Tribulations
 

I happen to like them as they can be made from common materials with
excellent ruggedness.
A 1/4WL ground plane takes one SO-239 and five pieces of
19 inch copper wire (or stingers). :-)

AND if you make it out of stiff wire (say #12 or so), it can be folded
to fit in a grab-n-go box and then unfolded when needed! The slight bends
caused by folding/unfolding may not look neat, but it's mighty handy!

--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)

J_Pole Trials and Tribulations
 

The J-pole crowd seems to tout fantastic claims about this antenna and I
....[snip]....

... my affinity for the j-pole comes from its simplicity and durability.
... Mounting is a dream -- it even works if you drop the low end into a
plumbing vent pipe. (How would I know that? ;-)
....[snip]....

I once made a J-pole from 300-ohm twinlead and tweaked it until it worked
OK while hanging from the ceiling, but when I moved it over next to a
wood-framed picture window (hung it from the window casing), the SWR went
to pot. Did I do something wrong?

(I concluded the J-pole must be VERY sensitive to its surroundings.)

--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)