Is a 2 meter antenna different than a CB antenna...

[Metal Twister]

Is a 2 meter antenna different than a CB antenna? If so what is the difference?

[Glenn D]

Yes they are different, the CB transmits in the 11 meter band, and the 2 meter in, will the 2 meter band.  The length is the difference.  The ?match? , the length needs to be right or the transmitted power comes back into the radio and will kill it.  They are both just lengths of wire that are the proper length to match the wavelength being transmitted.

The coax cable can be the same, and the connectors also the same, but the length of the antenna needs to match the radio. I use a fire stick on the right rear corner of my Jeep for the CB, and a MFJ duel band 2meter/44cm on the left rear.  It works well except that 50 watts out of the ham will light the display on the CB, when I had the 109? whip on the CB, it was not a problem. 

Keeping the tip of the 2 antennas at different heights helps.

[jchappy]

CB is 27Mhz and the ant. need to be tuned to that freq. range (you need a SWR meter for that)
HAM is the same way in that you need to tune your ant. to the specific freq. range your using (Cut to length)

[wiebewagon]

at some point at a M&G or something i want to have someone that knows more about CB radios to look at mine, i have a full length whip and a (i'd call mid grade) Cobra Radio that being said i cant seem to get them to tune properly.

[Glenn D]

With the full length whip, it is still a little short for a full 1/4 wave on the CB band. they are 109" long and are made to have a 3 inch spring under it to get to the full 112" length.  Also, using 18 ft of coax was the hot setup years ago, but with a SWR meter the coax can be cut to fit the length of the whip to provide almost a 1:1 match, without the spring.   

up to 1:1.5 is good, and above 1:1.75 is not the best, 1:2 or above is bad... 

Radio Shack used to sell them, bu now it they are Cell Phone & Battry shack..  not what it used to be.  With the mount in the middle of the roof on the full size woudl make a great setup.
 

[wiebewagon]

sorry about the  but thanks for the info, i think my problem might be in that i have a shorter spring or maybe something else, ill look at that stuff and maybe next time i wheel with someone smarter than me i can be taught more about it and get my stuff dialed in properly

[StvDiego]

at some point at a M&G or something i want to have someone that knows more about CB radios to look at mine, i have a full length whip and a (i'd call mid grade) Cobra Radio that being said i cant seem to get them to tune properly.

Just a thought; most off-road clubs do not allow "whip" antennas on their runs/events....

More on differences:

Radio signals transmit in "waves" (see pic below). Think of dropping a rock in water, the ripples that move away is the energy moving through the water from the rock hitting the surface of the water. The bigger, or faster, the rock, the bigger or faster the waves and the effect on the distance between the waves (wavelength). Radio waves are energy (ripples) waves moving away from the tip of the cb antenna.

In radio frequencies we determine the wavelength by dividing the speed of light (how fast a radio energy moves - like how hard the rock was thrown in the water) by the frequency of the signal (~3.00 ? 108 m/sec - the cb freq)

Ideally, a radio antenna would match the length of the wave. CB radio begins at about 25.01 megahertz (frequency) and using the formula above a full wave length would be about 39.34 feet long. That would be a little big for a mobile antenna so we have antennas that are a fraction of the wavelength: 1/2, 5/8, 1/4 and 1/8 etc. The 1/4 wave length antenna at just under 10 feet long is the whip antenna mentioned above.

Antennas like the Firestick are wound with wire to "cheat" and load the antenna to match the wavelength and trick the radio signal into believing the antenna is a full wavelength, or 39+ feet tall.

Now 2m ham 19"s.... Doesn't match the cb range

All pretty simple