we actually got lost on our trip today and I jumped on a 2 meter repeater 
and found some very nice people that got us right where we wanted to go.
----- Original Message ----- 
From: "Kenneth Lee" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, January 15, 2007 3:14 PM
Subject: Dual Antennas was :RE: antenna building


> 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
>