Please buy and READ some antenna books or search the web

It would take pages here to explain antennas to you.

--
Caveat Lector



wrote in message
oups.com...

Howard wrote:
On 8 Jan 2005 18:19:19 -0800, wrote:

How would you go about tuning a ground plane antenna? Is a ground
plane
a good antenna for 2 meters/440?

On another note, I have read about discone's being very broad
banded.
Are these the best antenna for scanner listening?


A 1/4 wave ground plane is tuned by varying the length of the
radiating element. Calculate the length, add a bit for good measure,
build it then tune it by pruning the length (in small increments).
The tuning can be done using an SWR analyzer or as most of us do,
with
a radio and an SWR meter.

Discone's do offer broadband coverage, though I don't have direct
experience to say they actually work well, great or poorly. I do
know
that for my scanner I use a 1/4 wave ground plane that was built for
220 MHz and it works fine - for a reference point though I am in an
urban area and most of what I listen to is within a 15 mile radius.
In order to decide what's best you should first establish your
purpose; are you in a fringe area, do you need directional coverage,
do you scan a wide range of frequencies or are your listening
interests all in the same "neck of the RF spectrum"?

Do 1/4 wave ground planes work well for 2 meters? (Send and receive).
Would they work as well as a j pole? What if you use different size
elements?

I just did not know what a discone would do for 2 meter send and
recieve compared to a ground plane.

On the scanner, I live in a fringe area for police but can pick up the
police on a homemade wire 1/4 wave for 450 mhz about 20 miles away.

What eventually I would like to do is pick up air traffic. And also
pick up various other frequencies like ambulance, state police, etc.
or your scanner do you use one antenna or several?