View Single Post
  #14   Report Post  
Old January 9th 04, 03:37 AM
John Smith
 
Posts: n/a
Default


"Desmoface" wrote in message
...
How about a J-Pole? Low angle radiation. The bottom end can be connected

to
earth ground. In fact, I constructed one using a mast with the 1/4 wave
parallel section added 1/2 wave below the top. Real easy. No radials.


thats also an option..i wonder if'n I'll need radials with a vertical

dipole??

Steve
kb8viv



As others have replied, no you don't.

I once made a 1/4 wave vertical and was listening to a local conversation on
my IC-2AT when there occured a lightning stroke from a thunderstorm a few
miles away. Although the mast and radials were grounded, the conversation
disappeared for about 5 seconds and then faded back in. Electrical charge on
the ungrounded vertical element. But I have never had this problem with a
J-Pole since all parts of it can be at earth ground. I've also used folded
vertical monopoles with the same results.

In my old age I have probably become paranoid about ungrounded driven
antenna elements. I know that some (maybe all) commercial antennas are
designed with networks or other devices which does the grounding. If I were
to build a simple ground plane today, I would make it a bit shorter than
resonant and add a shunt inductor across the feed point. That way there can
be no static accumulation on the element.

By the way, we sometimes get sand/dust storms here. I have seen and heard
the repeated discharges from the center pin to the shell of a PL-259 on a
RG-8 line coming down from the roof during a sand storm.

Anyway, this is not to convince anyone that a J-Pole is a cure-all or even
the best choice. I just wanted to tell about what drives my choices and tell
about a couple of my experiences. Anything you choose will be just fine, as
long as you are aware of its properties.

Have fun.

John - KD5YI