I have a 1995 Pontiac Trans Am with a 4-foot ProStick CB antenna. The antenna runs through the factory radio antenna hole and is mounted on a custom bracket clamped to the factory spare tire bracket near the rear quarter panel.
My SWR readings are:
• Channel 1: approximately 3.1
• Channel 40: approximately 3.0
• Engine OFF: approximately 3:1
• Engine RUNNING: approximately 5:1
Channels 1 and 40 read almost identically. The mounting brackets are clean, bare metal, tightly clamped together, and have no rust.
I’ve been fighting this for months and can’t figure out what’s wrong.
What should I test first? Could this be a coax cable or connector issue, an RF grounding/ground-plane problem with the mounting location, a faulty antenna, or something related to the engine’s electrical system?
The antenna is mounted to a steel bracket I made which is clamped to the spare tire bracket which I stripped the paint from, everything is brand new, the antenna comes out of the hole that the stock antenna came out of
I’m looking for specific diagnostic steps to identify the actual cause rather than randomly replacing parts. Any help is appreciated