[TowerTalk] J-Pole Antenna on HF Bands

[Ron Youvan]

Hi:

> << I have a J-Pole design sheet that gives all the formulas for constructing
>
> this Vertical Antenna in the VHF regions.
>
> My Question:  Is the J-Pole limited to the higher frequencies, or can it be
> also be used in the HF spectrum?
>
> If so, will the formulas work at these lower frequencies?  >>

  Yes, and . . .  A "J pole" antenna is a 1/2 wavelength antenna feed by a 1/4

wavelength stub, total length + 3/4 wavelength. (shorted on one end and open on

the other, one side connected to the end of the 1/2 wavelength radiator, with

the feed line connected at the point between zero Ohms of the shorted end and the

10 k Ohms of the open end that matches the feed line impedance.

Total length = 3/4 wavelength.  If the Super "C" antenna from `GAP' doesn't pan out,

I plan on erecting a very light weight (thin) tower 100' high and mount a 1/4 WL

(30 feet) pipe 2-3 inches away, shorted at the bottom open at the top and fed

50 ohms up from the (bottom) bonding connection.  (base grounded for lightning)

  60 feet of radiator (the tower 6-8" face) will resonate at 7.0? mHz, (not 64, as is

used for wire antennae) with 30 of stub below it, bonded to the tower 10 feet up.

A 40 meter "J pole."  Putting a 10' pipe inside at the top (a foot or so sticking

out) and moved up out of the tower, held with hose bands will allow it be tuned.

Formula not needed at these frequencies.

  73 (= Best Regards) de: Ron ka4inm@qsl.net
VISIT my HAM WEB SITE at: http://www.qsl.net/ka4inm
  using LINUX here & loving it!




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