Thread: J pole
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Old June 1st 04, 12:14 AM
The Masked Marvel
 
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Receive only antenna shouldn't be nearly as critical as x-mit. fat tubing
(say 1/2" copper water tubing) will be wider band than say 1/8"
brazing/brass wire.

A search for 2 meter J-pole or VHF J-pole will turn up a lot of amateur/ham
antenna designs, just shorten the lengths to 146 MHz / 159 MHz (0.92) times
the published lengths.

You also can make a 1/4 wave ground plane antenna w/ a SO-259 (UHF)
connector (or other flange mount RF connector) and a 17 1/2" (about) piece
of brazing wire or small tubing vertical in the center lead solder socket
and 3 or more (4 is easest) 17 1/2" wires attached to the coax shield
grounded mounting flange and bent downward 45° or so. Google for home made
ground plane antenna (and/or 1/4 wave, 2 meter, VHF, etc.) again scale 2m
dimensions by 0.92

Performance for either should be similar, again the fatter the element
diameter the broader the bandwidth, but for receive it is less critical than
for transmit.


"Tom Ring" wrote in message
...
Richard wrote:
Whenever I think about a simple VHF wideband omnidirectional vertical
antenna for my marine band listening, I'm always thinking folded dipole.

I
think I've got folded dipole on the brain. But wait - isn't it better to
make J-pole. Constructionaly simpler I think, and you can feed with
unbalanced coax. Are J-poles wideband antennas? I want any antenna to

cover
156-162 MHZ (6Mhz bandwidth) - RECEICE ONLY. Would a J-Pole do here,
bandwidth-wise?TIA.


A search on google found this marine J-pole.

http://www.arrowantennas.com/j-pole.html

Looks well put together, and covers what you want at 1.5 to 1 claimed.

tom
K0TAR