Just 'theoretically' speaking with price not being an object.
I am interested in:
-Simulation of electromagnetic behavior of box with circuit board in it. I doubt I would be able to get any kind of RF models for any of the parts I use (say DDS chip from AD, high speed op-amps like 1-4GHz gain band width (the serious opamps) for things like active circulator design). I suspect that the optimal PCB layouts might result in boxes that look weird like having triangle shapes and stuff. I suspect that setting up a usefully accurate electromagnetic simulation of a PCB is outside of my interest because I think you would either need some kind of automated characterization system or do alot of cold calling and begging to get useful models, nor do I find it that interesting on a PCB level to justify simulation.
-Simulation of waveguide things, like those filters that have the little disks that hang off of little rods that you adjust (BPF), I can see myself making something like that if I ever get a lathe and mill, end launchers, different forms of waveguide like circular, flexible, so I can learn to see what happens electromagnetically due to impedance mismatches and to analyze the effect of manufacturing tolerance on waveguide properties.
-Simulation of horn antennas. I see that with tools like the $6000 dollar 5(or was it 6) axis mill that is capable of making cuts in materials like aluminum and even stainless steel or titanium (at a slow rate but how many antennas will I be making), I am interested in those horns like the ones that have dual polarity, bastardized conical shapes, etc. I am not really that interested in other antenna types because the horn seems to be kind of like the best antenna for what I am interested in, I was looking at eventually being able to make my own series of standard gain horn antennas for a wide microwave frequency range when my fabrication skills reach maturity.
-Simulation of dielectric materials to try to optimize a home made EMI chamber with home made foam that I can categorize with the dielectric measurement methods as suggested by someone in another thread, to see how things like layout of cones, geometry and materials composition all come together in anechoic chamber dynamics.
-simulation of microwave reflectors for making things like dishes that are used to communicate with satellites
-simulation of polarization filters (I guess its just a special type of dish)
-simulation of microwave heating apparatus for small samples (like making your own microwave oven with a waveguide feed for heating small things like 'shelenk ware', which would fall under the subset of high pressure medium temperature chemical reactions that have unique reaction dynamics due to the nature of the microwave heating the sample
All these things are not really super dB sensitive and I am suspecting that my manufacturing methods will result in big errors.
I am not that interested in simulating something that will be 0.005 dB accurate, I noticed that most electrical work I do ends up being kind of ratiometric in nature anyway. I thought that certain programs might be catered to designing things with really narrow pass bands, phase coherence, stability
I am more interested in kind of cool physics apparatus then very tight specifications on communications systems, super high repeatability, metrology grade PCB's for use in microwave equipment etc. I don't really see myself doing board level microwave design, it is the least interesting to me because you need to get the PCB made in a factory anyway, it seems the other stuff you can maybe do in a machine shop with enough iterations. I don't think having SMD parts models would be useful for me at all.
Visual representation of fields is very important to me so I learn to imagine what is going on inside of microwave cavities, resonators, antennas, and so on. More so then bode plots and measurement graphs of insertion loss. I also am interested in seeing how microwaves react with bulk dielectrics for things like paraffin lens in experiments
Also stuff like trying to model a structure (say a shed, small building, signs, fences, other common obstructions) in solidworks with realistic materials to see how radio/microwaves are effected by it so I can better understand what is happening with outdoor antenna uses and behavior of radar systems to better understand things like radar cross section of airplanes, stealth aircraft features, etc. Maybe even trying to make a model of my lab and seeing how it compares to real life when lightly irradiated.
Alot of it is that I want something like a 'gmod' (if you played the half life 2 mod) for messing around with RF stuff. I don't expect to make any money learning any of this for any kind of manufacturing purpose. I just really can't imagine half the stuff people talk about and it would help me so much to get cool RF predator vision.
Like with solidworks, I am modeling heat-sinks and cooling systems, but I am never gonna build it like the model, I just want to learn the relationships between different elements to get a good idea of how I can over engineer something properly. Exact simulations I think are typically useful if you want to save money in large scale production, but it would be too much of a pain in the ass for me to build 5 heatsinks with different fin spacings to get an idea of how the spectrum of design choices effects thermal transfer. I am trying to put boundaries on absurd design choices, not hone anything. I know microwaves are alot more sensitive then thermodynamics however, but I don't really see myself sitting there for days on end trying to shave off a fraction of a dB or something, its just really easy to do something completely ridiculous with electronics.
I know its possible to kinda do things by learned intuition and feel, especially after reading documents from the 1970's where they tend to use peacewise approximations and stuff for research, rather then simulating some super refined model... I wanna be able to get that without all the aids a well funded researcher back then would have. (like the work of John Kerr with his dual ridged horn designs)
A useful simulator would probably save me thousands of forum posts.