RE: NEC-LIST: J-pole modeling, also LPVAs

I never thought of feeding the Jpole like you did. I have modeled and
made several 2 Meter and 70 CM Jpole's. The 2 Meter ones were very
close to the model. I could never get the 70CM ones to work as modeled.
Had to shorten them to get a match. I was using a flange mount SO239,
N-Type on the 70 CM. I figured out that the stray cap was the problem.
Will have to try your method.

Peter D. Richeson/KA5COI
Email: peter.d.richeson_at_boeing.com
"I don't believe in a no-win scenario." - Admiral James T. Kirk
 I do not speak for any one but me, and some times not even for me.

> ----------
> From: w1gql_at_midcoast.com[SMTP:w1gql_at_midcoast.com]
> Sent: Wednesday, December 24, 1997 1:40 PM
> To: nec-list_at_ee.ubc.ca
> Subject: Re: NEC-LIST: J-pole modeling, also LPVAs
>
> Here is how i modeled a j-pole for 2. I used 6 wires each 1/2 inch in
> diameter. 4 wires form a rectangle at the bottom of the jpole. the
> vertical sides of the rectangle are 1.5 inches long. The horizontal
> sides of the rectangle are 2.5 inches long. extending up from the
> upper left corner of this rectangle is a wire 56.5 inches long.
> extending up from the upper right corner of this rectangle is a wire
> 17.5 inches long. The antenna is fed in the center of the wire
> forming the top of the rectangle. When I actually built the antenna I
> made if of 1/2 inch copper tubing. I made the top (fed) pipe section
> moveable so that it could slide up and down a little way. I did this
> by using a 1/2 inch copper "T" which i cut open the whole length of
> the long side of the "T". By spreading out that side of the "T"
> slightly I could make it slide up and down over the pipe....
>
> I originally had planned just to run the outside of the coax to one
> of the vertical members of the jpole and the inside to the other about
> 1 1/2 inches up. I found by modeling that things worked better if I
> actualy made the cross piece of 1/2 inch copper pipe. When I made the
> antenna I cut this cross piece in the middle and fed the antenna at
> the cut.
>
> Antenna works great and SWR is almost as modelled!!
>
> If you don't understand this explanation, let me know your address
> and I will send you a drawing. Dave
Received on Fri Jan 09 1998 - 10:15:50 EST