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Date: | Mon, 15 Jan 2007 15:14:10 -0500 |
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Colin, I agree with your comments regarding using 2-meters verses the CB
band. I almost always have better luck finding info and help from the hams
(either on 146.52 or a local repeater) than from the CBers. Also, when I
listen to the CB band I have to use headphones because the language is so
terrible. I usually only use the CB when the traffic has stopped and I want
to know what's happened. I never use the cb locally, only on long trips.
Regarding dual antennas. Dual antennas can be very helpful in several
situations. I personally use a single 5-foot firestik on our minivan (for
10 thru 12 meters), but below is some good reading from Firestik's
web page regarding dual and single systems. Note also that Firestik
suggests that in most cases a single antenna is all that is needed. Here's
part of the article and the link to it.
http://www.firestik.com/Tech_Docs/SNGL-or-Dual.htm
CHOOSING SINGLE OR CO-PHASE ANTENNA SYSTEM
Compliments of Firestik® Antenna Company Technical Support Team
Copyright © 1996 Firestik® Antenna Company
Truck drivers' made co-phase antenna set-ups popular back in the early 70's.
There are several good reasons for their use. First of all, co-phased
antennas
create a directional pattern that favors communications in front and in back
of the vehicle. This is ideal for truckers and RV's that use their radios
to speak to those on the same road/highway that they are traveling on. If
you are speaking with someone in front or behind your vehicle and either one
of you take a turn and leave the more powerful RF lobe, a definite change in
clarity will be noted.
The second advantage of co-phased antennas is there ability to perform where
there is little reflective ground plane for the single antenna to radiate
its
energy from. For instance, on fiberglass vehicles or those with light
aluminum sheeting over a non-metallic frame. In those situations a co-phase
set-up
allows the antennas to use each other's radiation field to direct the
combined energy across the horizon. In order to be effective at least 2/3's
of each
antenna must have unobstructed line-of-sight to the other antenna.
The third justification for dual antennas involves situations where some or
the entire signal would be blocked if a single antenna was used. For
instances,
if you were pulling a large trailer. In such cases, having an antenna on
both sides of the vehicle prevents signal blockage. Note: Drivers that pull
large
trailers and choose to use one antenna will (should) mount the antenna on
the drivers side of the vehicle in order to maintain contact with vehicles
traveling
in the opposite direction.
One additional reason has to do with power. Stock CB's leave the factory
with the transmitter power limited to 4 watts but there is an underground
market
of linear amplifiers in existence. Inasmuch as power will eventually turn
into heat, and the antenna will be required to dissipate that heat, two
antennas
will more than double the heat dissipation abilities of a single antenna.
For general communication, with an Omni-directional radiation pattern, a
single antenna system is all you probably need.
.... Article goes on...
73, Ken -N5SWR
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