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Re: Dual Band J Pole



   Has anyone constructed a Dual Band (144/440) J Pole antenna, that they could
   supply the materials and dimensions used. Maybe you know of a Web page site,
   that has this information. Thanks for any help.. 73 N4Zq

Here's an extract from one from my WWW pages (with a copy of the linked
page).  This newsgroup is one of the few places where a dual-band J-pole
is worth pursuing.  Properly tuned, it won't hurt your rig to operate in
both bands, but the terrestrial performance at UHF is not very good.  If
you need instructions on tuning an antenna for dual band use, send me
e-mail.
			-- KD6PAG  (Networking Old-Timer, RF newbie)

-------------------------------------------------------------------------------

	...

Make a 2 meter J-pole [http://www.qsl.net/kd6pag/usenet/J-pole.txt]
antenna from 300ohm twin-lead. [You will need to trim both the short and
long directions.  See also a recent QST article, which may be a better
source, and also gets into dual-band operation.] This project has appeared
in several forms, and others may be included later.  Note there is some
discussion as to which side the shield should be connected to.  I also
recall WA6TVM [now SK] suggested in the local net, the 'Antenna Forum',
using a sleeve balun with one of these.  While you can cut one of these 
to have a decent SWR on both 2m and 440, the pattern in vertical plane
probably does not make this a good general-purpose dual-band antenna, with
the pattern on the 440 side mostly at 45 degrees above the horizon
(e.g. better for satellites than repeaters).

	...

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Path: agate!ames!titan.ksc.nasa.gov!titan.ksc.nasa.gov!nntp
Newsgroups: rec.radio.amateur.antenna,rec.radio.amateur.equipment,rec.radio.amat
eur.homebrew,rec.radio.amateur.misc
Subject: Re: Portable 2m Antenna for Mountaineering???
Message-ID: <1994Jan12.092451.1134@titan.ksc.nasa.gov>
From: Nguyent@snowmass.ksc.nasa.gov (Tom)
Date: 12 Jan 94 09:24:50 EST
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David,

Try a rolled up J-pole.  It's made of 300 Ohm Twin lead and tapped with a 
50 Ohm coax with BNC connector on opposite end.  It provides about 2.8dB
gain.  You can buy the ant from MFJ for  about $12 or build it yourself.  
The dimensions are below:
    -- for 146MHz center freq
                     |  
                     |
                     |
                     |
      this side	     |
           56"       |         
                     | | <---------------------------- trim  here for best SWR.
                     | |        14" on this side 
                     | |
       coax====- -  1-3/4"   tap from bottom
                     | |
                     ---

I've experimented with lots of these  with good results (built about 30 or so 
for myself, friends, and local HAM classes).

Good luck and 73,
Tom
AD4NA

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