The Amateur Radio Community [Hams] lots of electronic and Radio frequency resources going back to Radio's start. Lots of innovation and cheap tricks. The EM Drives are specially shaped closed cavity resonators. Normal cavity resonators are widely used as the oscillatory systems of generators (klystrons, magnetron's), as filters, frequency standards and measuring circuits.The Amateur resources tend to be more plain language. They also cover all the electronics as well. They have lots of Elmer's [Mentors]
Hams have satellites, Space station operations, moon bounce, meteor scatter, advanced signal processing tools, computer controlled radios, Slow Scan TV, packet radio [networked wireless data relay stations]. Hams worked on both mobile communications and data transmission to get equipment smaller and more reliable.
There are legal, safety, interference, shielding, efficiency power transmission/reflection and grounding issues. These high power Radio frequency systems can cause interference/damage to other devices.
Radio uses complex [real and imaginary] numbers for analysis There are math tools available.
There is also antenna modeling software available. These do generate correct models but indicate no thrust.