CB Antenna Ground
Hi Sober,
The coax cable has a "Force Field" around it in the form of a braided shield. This braided shield does two things, it helps prevent the radio signal from bleeding out of the cable and interrupting other electronic equipment near it ... and the braided shield provides a positive ground between radio and antenna needed for the radio to work properly.
But judging from your post, its not the ground thats causing your problem ... it sounds like you are not getting a proper "match" for the antenna and the radio, commonly called "Standing Wave" .. This can be caused by one (or all) of three things...
#1.. the antenna shaft is not of the proper length. (metal antennas only)
#2.. The coax cable not of the proper length.
#3.. the coax braid is in contact with the antenna shaft.
Just for information only,... for a CB antenna to work at it's full capabilities, it should have a metal area under or around it that will reflect the radio signal back onto the antenna..
example: metal roof of vehicle .. or if on a building like a home, the antenna needs radials at the base of it to reflect the signal back onto the antenna itself. These type of antennas are called "Ground Planes"
But the lack of a metal reflecting area does not mean the radio won't work.. it simply won't work as well as one with the metal reflector.
To make things simple for you ... do this,
borrow or buy a "Field Strength/SWR tester.. Commonly called an "SWR" meter. You will also need an 18 inch "jumper cable" to connect the meter between the antenna coax and the radio.
Then based on the reading the meter shows, trim the metal antenna mast down, using 1/4" increments until the swr/reflecting wave is within proper tolerances.. usually less that "1" but can be as high as "2" without restricting your signals..
If using a fiberglass antenna, the coax is the only way to correct the standing wave, without using a matchbox...
Don't worry, the meter comes with instructions and diagrams on how to connect and use the meter..
If for some reason you cannot get an acceptable match between antenna and radio by trimming the antenna or/and coax, there is a tuning device that you can get that will match the standing wave... In CBer's slang, the tuner is called a "Matchbox"..
Make sure that the coax is not more than 20 feet long or less than 16 feet. The proper length of coax used on a 1/4 wave or 1/2 wave antenna is (+/-) 18' 6". Also do not coil up the excess coax.. stretch it out so that it does not overlap itself.. This can be done by stretching the coax out under or on the dashboard or up in the overhead storage area.
NOTE: on some styles of antennas, the coax is shorter because of the way the antenna is made. The "Base Loaded" style of antenna is an example.
I taped my excess coax to the inside wall of the overhead compartment over the windshield.. out of sight and worked great.
Sometimes when people make up their own coax cables they accidentally allow the braided cable to ground out against the copper wire in the center of the coax or against the soldered connection of the PL259 connector.. (Thats the twist-on connector on the end of the coax)
If you bought a ready made antenna with cable, it is not likely to have that problem.
As for distance of a CB signal ... technically the signal emitted from a CB radio can travel completely around the world, but for practical purposes, the average distance that a CB is functional is about five or six miles on a open, flat terrain like some of those Texas or mid-western state's highways that seem to go on forever without a hill or mountain to be seen..
I personally have talked to South America from my home in Raleigh, North Carolina.. with my CB by using a five element powered beam antenna on the rooftop of my home.
That was 40 years ago during the CB craze that swept America.
ahh for the good old days...
Hope this helps,
John KDX1663 The "Raleigh Mailman" (1967)
