Behavior of Microwaves over Hemisphere

I've spent a lifetime dealing with various antennas. However, modeling only became possible when the computers and the software became available. For me the prime inspiration was taking on several consulting jobs with only a slight clue as to what I was doing. There's nothing like panic to inspire the learning experience. I actually did a fairly good job, although I must admit that I was slightly late. After that, it was mostly finding the time to read the docs in order to fill in the knowledge gaps.

Using NEC software is easy enough. There are front ends for the various Fortan NEC engines that make life much easier, such as Eznec and 4NEC2. The problem is that NEC2 works best with wires, not surfaces. One can simulate a surface with a mess of wires, but that creates segmentation problems. When I try to use a surface card, it can fail a sanity check. I've done beautiful looking paper antenna designs, that didn't work because of this problem. NEC2 also has no provisions for modeling dielectrics, does badly with electrically small antennas, and can't handle anything more complicated than a flat earth (ground).

I suggest you try using 4NEC2 which comes with a huge collection of sample antennas. Stay with wire antennas until you see how things work. Lots of tutorials on the web and on YouTube. Try something simple, like raising or lowering a dipole above the ground and see what happens to the pattern. Then, change the wire diameter, tilt the dipole, move some other unconnected wires nearby, etc.

If you want something messy, here are some sample TV antenna models.

I hear "carbon foam" and think charcoal (which is actually a sponge rather than a foam)

OTOH perhaps there's a way to mix a graphite mixture like electrodag

Add a hygroscopic salt to the water, choice of salt depends on relative humidity.

A disk with sharp edges will focus the waves behind the centre, there's a name for this effect which I forget.

Aren't these matters symmetrical? Won't the coupling be the same in both directions?

If i understand the physics correctly it should be. That does not mean that that i understand the physics correctly.

Dr. Hobbs can you further enlighten us?

?-)