How to generate a high energy electromagnetic wave? Using high voltage or high current?

I am about generating an electromagnetic wave which should be powerful enough. So I should manipulate its electric field and magnetic field simultaneously. As far as I know E amplitude depends on the voltage in the circuit and B amplitude depends on current intensity. I do not have any idea to generate EM wave. Which method is infeasible and efficient? (high voltage or high current)

• Your "high voltage" may be my low voltage. My "high current" may be your low current. I can answer this question for you (see below), but in general when asking an engineering question avoid statements like "powerful enough", "high", "low", "bright", "dim", etc. Ask in engineering units (amps, volts, kg, etc.) If you don't know how much of something you need (i.e., what is "powerful enough" then in a separate question describe your task and ask that (i.e. "how much heat do I need to light a candle")). – TimWescott Jan 18 at 21:05
• should be powerful enough ... what does this mean? – jsotola Jan 18 at 22:51
• talk on your cell phone .... that generates EM waves – jsotola Jan 18 at 22:52

If you are generating an electromagnetic wave in free space then the ratio of the E field to the H field is fixed at 377$$\\Omega\$$ (yes, ohms -- the units work out).
You would hope that would answer your question, but it doesn't because in order to generate a pulse or continuous waveform of electricity and turn it into an electromagnetic wave you need to couple from your circuit to free space (or to whatever material you want the electromagnetic wave to be in). The device that does this is an antenna, and depending on their design antennas can have very different input impedances and efficiencies, even though the EM field that they generate has a ratio of E to M of 377$$\\Omega\$$ in free space, or the characteristic impedance of whatever material you're launching the EM pulse into.