View Full Version : Fiberglass antenna springs

05-25-2019, 07:25 PM
This is going to seem like a silly question, but I can't seem to find an answer for it. Does a fiberglass antenna require a spring in order to be able to tune it properly? A spring adds several inches to the length of the antenna, and 1/8" can make a big difference in SWR. I have talked to a few experienced CBers, and have been told both that I do not need a spring, and that I absolutely need a spring. I know that the lower the frequency the longer the antenna needs to be. Are some fiberglass antennas made to be used with a spring, and others without a spring? The last base station antenna I used was a vertical 102" whip with a spring on a mirror mount bracket, bolted to the wood fascia of my house, then a heavy gauge wire of approximately the same length attached to the mounting bracket, and run along the edge of the roof, basically creating a dipole with one vertical 1/4 wave element and one horizontal 1/4 wave element. It worked very well. I got no readable SWR at all. I'm trying to tune a 4' mobile fiberglass antenna, and cannot get the SWR down. Do I need a spring. Sorry for all the rambling.

05-26-2019, 07:24 AM
If SWR is higher on channel 1, than 40, then your antenna is too short..."Add the spring"...

05-27-2019, 04:34 PM
The fiberglass are usually wire wound internally. Is it top loaded, bottom loaded or no load. determine the SWR at ch 40 and at ch 1.

05-29-2019, 09:48 AM
sometimes fiberglass or any antenna with a solder joint can fail at that solder joint and the antenna will never tune at it's intended frequency . is it a new antenna or old ? even new ones can be a lemon but it is rare . you may also not have a good ground connection for the ground side of the antenna . if you still have the 102 with the spring try it on the stud on tour mobile to see if you have a similar issue . if you do the issue is in the ground or install . if you don't something is up with the FG antenna . or .... if you have a antenna analyzer you can use that to find where the antenna will tune and if it's close to the cb band some additional tuning should help . if not then try another antenna AFTER tripple checking your install for good connection to RF ground on the vehicle and no shorts between ground and hot on the antenna mount .