BM, this is a very interesting article and the evidence presented may be right on the money in the purest sense, but in the real world where we have all kinds of stuff on the surface of the earth and other interfering radiation around our antennas and in the far field as well---such conclusions as noted in the article cannot IMO be considered as categorical regarding antenna success.
You may have noticed that the author's basic premise in observations were probably true, but he also moved his antenna a considerable distance when evaluating his comparisons. He also talked about the earths conductivity in his modeling and used average ground, but in his real world experience his results were developed from two totally different locations.
Ask yourself, what if his trip took him to an area of very good soil based on the ms/m figures he modeled, and while he was at home the soil conditions were over extremely poor soil? The modeling will not analyze those differences and therefore consideration must be made by the reader for those differences. Even if everything in the article is absolute truth, this should give you pause to reconsider.
BTW, on the last topic above, IMO there is a difference in performance between different antennas when over different soil conditions. The article suggest that all antennas respond the same to height changes, but what if the location changes. In the real world, you can't have your analysis both ways---and I'm surprised he made that statement in light of his moving his antenna.
Now, with my own experience I find just like is often claimed--- higher is better and that may always be true with local ground waves and direct line of sight signals not-with-standing interfering stuf on the ground.
Recently I got back to comparing my antennas since hurricane Ike blew through here. I mounted an A99 on a 10' mast and leaned it up against my house. My eves are 8'6" high and the roof peak is 17'8" high. Just like earlier observations I had at least two issues concerning height and stuff that interferes with my antenna signals. With my A99 feed point at about 10' high and leaning up close to my roof the antenna worked, but it was noticeably attenuated to signals on the opposite side of my roof and in fact was perceived to even be a little directional. I raised it up to 15' and I saw noticeable improvement, but IMO it was not due to the increase in height---the antenna was reacting negatively to being too close to my roof---wood and tar based shingles. It was not due to wiring, duct work, or plumbing in the attic either, because there were none of such items in that area or even nearby. I move the antenna at 10' high out away from the house and the improvement was very similar to the antenna at 15', but I still sensed some attenuation, so I raised the antenna to 25' and boom all of the radio signals to the north were noticeably better. I figured this was due to the increase in height, but the "shadow affect of my roof being higher than the base of my antenna," as mentioned in a patent on the Avanti AstroPlane antenna or in the antenna manual, was the cause of the problem I was seeing and height only had a minor effect in that case.
I did eventually get my AstroPlane up and it too reacted just like the A99 had done when put it through similar paces. The surprise for me was that the AP did not resolve the "shadow affect." The way I read the info was that the AP would solve the problem, but maybe I put the antenna to a unfair level of consideration, because the Avanti images describing the "shadow affect" show the base of both antennas well above the roof peak of the house where the antennas were located.
I say all of this, because I just got through going over many of the observations that likely relate to the height questions in your thread. For me the undesirable range limit of zero - 1.5 wavelength in the article probably covers just about the limits of most CB operators working range for installs, so what are we to do?
In my area, I have 60'> trees everywhere and I'm still able to work most of what I would like with little tale-tale signs of attenuation. Would 100' be better? Of course that would put the base of any antenna I put up well over all the trees and that would be better. I've have had antennas up there several times over the years and that usually did make a difference, and when it didn't I figured it may have been because going higher changed the tune enough and has some attenuating affects. I saw this happen with an A99 that had a good tune at about 30' feet, but the tune went south on raising to over 60' and that surprised me.
