SW, I'm not suggesting that sky wave radiation is to be ignored. This seeming compression thing is just one issue that I was surprised to see, and I heard 55 talk about this factor when I called him to ask for a Merlin to test and I would return it when finised or buy it. I still want to test the Top Hat with a coil underneath.
I believe that we are affected by sky waves in our local contacts much of the time, and sometimes they are good and sometimes they are not. I can't explain it any better, but I think Bob has a sense that determines for him when a contact is or is not affected by shywave propagation.
LC, I think my model Top Hat is about 60% in the vertical radiator. My AstroPlane knock offs and the New Top One are closer to 50%. I just took my Old Top One down with a full 1/4 wave in the top vs. my New Top One, that I've been comparing for several days. The local signals are very similar with an edge for the full 1/4 wave radiator, but I did not notice the distinction in DX or local that I've noticed before, so I'm not sure about my thinking on the subject. I will say some folks claim a Top Hat antenna cannot perform at or near par with a full 1/4 wave radiator, but IMP they are wrong to be so categorical about such a claim.
I did not model any matching in any of my models. I don't know how to model matching devices at this point. Among all the full blown Exnec models I ever seen, none showed a matching device.
I have asked MrSuburban and I think I asked Shockwave and a couple of others for a model with matching included, but thus far no models have been received. I get none to few responses to my questions asked of others regarding modeling in fact.
I have read in places and Henry as intimated to me that method of moments modeling is not based on a particular antenna being matched. So, I assume that matching makes little difference to the end results we are likely to get from the modeling efforts. I can skew a 1/4 wave to have a bad match by physically making the elements show a non-resonant mismatch that is considerable. This is similar to several of my models posted above demonstrating the use of 102"/108" whips and in particular the model with no ground plane at all. I also find in my real experience, within reason, where tuning an antenna has little to really do with the antenna's performance...as best I can tell. I am also doing a real life test model for this idea right now using a 102" whip with no ground plane attached to emulate a heavy mismatch.
Bob has suggested to us many times that tuning the Sigma4/Vector is the secret to best performance at a distance, and in that case if true, I think it has more to do with the collinear affect we suspect is at work in such an antenna. If this ever develops to not be the case, then it goes back to Shockwave's idea about sky wave proprogations...that convinced Bob of what he saw.
I have never really tuned my Sigm4, just constructed it per instructions, and it works fine, in fact it was #1 along with my New Gain Master in my recent testing. So, one day I will have to try and duplicate Bob's ideas. The reason I haven't tried it already, is because he also says the response is less dramatic with the original Avanti Sigma4, because it only has three legs and I also agree that may be true as well. I have prov en several times at my location that I see better results when adding effective radials to my MarconiX antenna.
The big issue with a proper tune is making the TX'r happy in operations, so that it will provide 100% of its energy toward the antenna...and then other factors come into play like the feed line, connectors, inline devices, proper construction, and objects around the antenna may start also ill-affect performance.
As noted in my model of the Top Hat 1/4 wave above it could stand some matching help, because it shows the resistance has gone back down from close to 50 ohms in the conventional model with slanted down radials, to 39 ohms again. This is probably why the Merlin and others like it have the coil added in series to increase the resistive feed point value to a better match.
Just my ideas, not facts.
BTW LC, you mention some laws of the universe. Can you elaborate some more on these laws? Which Maxwell are you telling us objects to something said here, and do you have a direct link to such a subject and a claim that Maxwell made?
