That is odd! I honestly doubt if changing antennas was the complete problem, but it sure brings the fact out that there is one. As close as that antenna is, I very seriously doubt if it's because of any differences in the antenna's radiation pattern, no matter what kind of antenna it is. 'RF' may be the problem but not because of the antenna's 'size'.
I'm wondering about a few things. You said an airbag had to be replaced, after it was, did the cable follow the same routing as before, or was it moved any? Sometimes, it doesn't take a lot of difference to make a difference.
I also wonder about those USB cable and what they are 'connecting' to the laptop. Any significance/susceptibility to RF from them? Since they aren't 'connected' tot he radio I don't see why it would affect the radio, but it may 'point' to a cause, sort of.
The 'other' way of RF getting to the radio and the computer especially is through the power lines. (I hate those @#$ inverters, wonder why they don't just do the DC power directly from the DC supply like they used to do?) The power source and lines would seem to be a much more probably entry point that just RF. I use an inverter too, but don't use the car's cig.plug, it's wired directly to a second battery through an isolation device, same for the radio and laptop. I haven't noticed any significant problems so far. (Long story about that, you don't wanna know.)
Very basically there are two routes into things by RF, radiation, and conduction. The problem has to be with one of them. Ferrite 'beads' do work, but are not always a 'cure'. So is distance between cabling for various things. I have to think there's something neither of us are thinking about so the 'trick' is to find that 'thing'.
Good luck! If/when you do find the problem, I really hope you let us know about it.
- 'Doc
