Antenna Question: Handheld's vs External Discone or Scantenna ?

Antenna Question: Handheld's vs External Discone or Scantenna ?

Post by Robert1 » Sat, 30 Aug 2003 20:59:31

Hello:

Question regarding handheld scanner aerial (the ***-ducky kind that comes
with unit):

Assuming that I have all of the following 3 aerials at the same height,
would there
typically be "much" of a difference between what the handheld would hear
with it's own aerial, compared to, e.g.,
an external R/S Discone or Scantenna aerial connected to the scanner ?

[again, all 3 at same location and height]

Thanks,
B.

 
 
 

Antenna Question: Handheld's vs External Discone or Scantenna ?

Post by Ralph Mower » Sat, 30 Aug 2003 21:12:56


Quote:> Question regarding handheld scanner aerial (the ***-ducky kind that
comes
> with unit):

> Assuming that I have all of the following 3 aerials at the same height,
> would there
> typically be "much" of a difference between what the handheld would hear
> with it's own aerial, compared to, e.g.,
> an external R/S Discone or Scantenna aerial connected to the scanner ?

> [again, all 3 at same location and height]

There will be a big differance in most any antenna that is broad banded over
the  one on the handheld.
On one of my ham handytalkies I could not hear the weather stations with the
antanna that came with it.  Ran some test on the receiver with a service
monitor and the sensitivity was about the same on all frequencies.  Put
another antenna on the HT and it would receive just fine then.  After
running a few quick and dirty tests by hooking a service monitor up to a
whip antenna and going across about 15 feet to the other side of a room.  I
set up a HT and put on one antenna afer another and would adjust the output
of the service monitor tuil the squelch broke.  Out of about 4 antennas
(*** duck type) I tried I found some were as much as 10 times as
sensitive on some frequencies as others were .
In other words each one seemed to be more sensitive on a differant frequency
.
 
 
 

Antenna Question: Handheld's vs External Discone or Scantenna ?

Post by DougSlu » Mon, 01 Sep 2003 09:27:11

It would depend on the frequencies you are monitoring.  Duckies tend to be
optimized for certain ranges (often leaving dead spots or nulls in other
ranges) whereas the Discone or Scantenna are wideband designs.  At UHF, the
loss in the coax feed line from the external antenna could tend to reduce
the signal available at the receiver as compared to the directly-mounted
ducky (depending on coax quality and length of course).  Another thing to
consider is that an external antenna with some height could overload the
receiver, making it seem like it does not work as well.  Adding an
attenuator helps this problem.

So as you can see, there are more variables than just antenna type and
height.  Frequency, type, length and impedance match of the antenna feed
line and receiver quality are among the others that need to be considered
before you could draw a proper conclusion.

All that aside, I think a discone or Scantenna would probably be better in a
"typical" case.

 - Doug


Quote:> Hello:

> Question regarding handheld scanner aerial (the ***-ducky kind that
comes
> with unit):

> Assuming that I have all of the following 3 aerials at the same height,
> would there
> typically be "much" of a difference between what the handheld would hear
> with it's own aerial, compared to, e.g.,
> an external R/S Discone or Scantenna aerial connected to the scanner ?

> [again, all 3 at same location and height]

> Thanks,
> B.