Antenna Height

If your talking VHF or UHF your discone does not have to be high because
VHF and UHF signals are line of sight mostly. The only reason you elevate
the discone is to be clear of metal obstacles. Metal near ANY antenna will
affect the reception and almost always negatively. Thats why the discone
just laying on the couch only sounds marginal better up higher.
I have mine hanging from a tree limb 30 feet up to have it clear the shadow
of the house.
Discones do not have much or any gain. .
If you are interested in long distant reception in you need a vertical or a
yagi antenna to pick up those distant signals. Both vertical and Yagi
antennas have gain.... each Db of gain increases the signal 10 times.
Thats why a discone which does not have any gain at 70 feet is as good as
one at 20 feet. Even though it is up much higher and should see farther
the signals from far away are too weak to be picked up by the
discone. This is not true for a vertical or yagi antenna.

Now on HF higher is always better because the signals bounce between the
earth and the ionosphere... so when you put it up higher
you get more signal. Also if you use a long wire antenna, reception is
always improved by using an antenna tuner.

Antennas are like flutes they have to be the right length in order to
resonate (amplify) the frequency of the signal you are interested in.
Otherwise you will not pick up a lot of signals that are there if it is not
intune with what you are listening to...

To calculate how long an antenna needs to be... take 300 and divide the
frequency you are interested into it. This will give you the answer in
meters... and example 144mhz into 300 yields around 2 meters. So the
higher the frequency the shorter that antenna.
Seeing the cell phones operate in the 800mhz range that makes the antennas
needed very short. Antennas can be a harmonic of the fundamental
frequency.. they can be 1/2 wave 1/4 wave or 5/8 wave. The above formula
gives the answer in full wave length.

There is no ONE antenna that picks up everything. Invest or make a switch
box to switch between antenna's. Seeing you are only using the antenna to
receive an not transmit, regular small switches can do.

Here's a link on propagation
http://www.arrl.org/tis/info/propagation.html

use the arrl.org site to learn more about antenna's and such....

I think antennas are one of the fun things about radios... for $20 USD all
you need is wire and insulators and sturdy string and some trees and you
got the ability to pickup SW stations 10,000 miles away... When I put up
my second long wire up at 70 feet in a tree - I picked up Turkey the first
time ever from Florida... on long wire the direction of the signal is the
direction the wire is strung.

Robert Rathbone
KG4WKM
Florida

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>>Robert Rathbone KG4WKM Florida
>> said

>> Both vertical and Yagi antennas have gain.... each Db of gain increases
the signal 10 >>times. Thats why a discone which does not have any gain at
70 feet is as good as
>>one at 20 feet. Even though it is up much higher and should see farther
>?the signals from far away are too weak to be picked up by the
>>discone. This is not true for a vertical or yagi antenna.

This is inaccurate. Doubling the received signal would result in 3 db gain
(1/2 an S unit). In VHF/UHF the practice is to raise the antenna as high as
possible, especially if the antenna provides unity gain. There is a point
of 'no return' however. The losses in some cables can negate the increase
in signal levels.

I've always followed the policy when dealing with VHF/UHF....."Use as good a
cable as possible and get it up as high as possible". Discones are
excellent antennas for the PCR-1000.

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