I depend on my models for information, but I'm not sure about these mobile objects I use.
Well DB, to this point I have little to no confidence my mobile objects being anywhere near accurate, and that is why I posted the comment above. I would leave it to the reader to go back and reread the article and pay attention...if they missed that important distinction concerning the length of the ground side of the line.
To give a visual of this effect in modeling...it is to be noted that when the mast touches the ground in the model "O" with a little circle inside...the feed line length for both the shield and the center conductor would be identical, and that is a difference that must be understood. As Bob will probably note...such a situation is likely to not be possible in our antenna work at home and in our back yard. The center conductor and the shield length to ground will not likely ever be the same length.
W8ji is correct, however, that is not a complete explanation of what is happening in the stated situation, namely a mobile environment. A few questions for you.
Yes IMO W8JI is right, but there is a lot more to consider that the words here cannot likely explain easily. I too will put mobiles in a different category in this case, but I'll leave that to you to explain.
Personally I never noticed the ill-effects on performance when CMC were manifest in my CB system. Maybe my antennas did not have bad enough issues with CMC. However, I did think I was able to tell there were CMC on the feed line, but I wouldn't bet my life on the fact. IMO there is likely little to no way to really tell how or if these CM currents help or hurt performance, even though I've heard a lot of symptoms being solved immediately upon stopping these currents from manifesting themselves locally. Similar stories to accounts about earth grounding and antenna responses come to mind. IMO a lot of that is likely in the imagination of the operator.
Sometimes my models show enough CMC on the mast that I see it ill-effect the pattern produced and sometimes I see the CMC seem to help the far-field gain and pattern produced.
So, if there is any truth in my observations and models here...then I doubt there are too many out there that will be able to really do anything...except possibly minimize the CMC from manifesting locally to there station. But again, I don't see how they can determine if eliminating these currents helped performance or not, I never have seen it happen.
On two occasions with antennas that acted very badly in this regard...I got local reports the antennas performed with a bit stronger signal than other antennas I had up an working at the same time and that suggest to me that CMC can also be of benefit in some situations.
The key is its grounded at the source end Eddie,
Yea Bob, that is why I called attention to the specific sentence in W8JI's article where he made the same claim.
I even highlighted it by underlining it, because I think most CBr's overlook the very important distinction you just made.
ohh ok Thanks for clearing that up guys! 
