"Microwaves are defined as electromagnetic radiations with a frequency ranging between 300 MHz to 300 GHz while the wavelength ranges from 1 mm to around 30 cm. Microwave radiation is commonly referred to as microwaves. They fall between infrared radiation and radio waves in the electromagnetic spectrum."
https://byjus.com/physics/electromagnetic-spectrum-microwave/
"microwaves can generate electrical current in any conductive metal they encounter."
https://fear-of-lightning.wonderhowto.com/how-to/making-electromagnetic-weapons-directed-microwave-energy-0133231/
"Using fibreglass and copper conductors on a circuit board, the researchers converted microwaves into 7.3 volts of electricity. A USB charger, which is often used to recharge mobile phone batteries and cameras, provides about five volts.
"We were aiming for the highest energy efficiency we could achieve," said team member Allen Hawkes.
"We had been getting energy efficiency around 6-10%, but with this design we were able to dramatically improve energy conversion to 37%, which is comparable to what is achieved in solar cells.""
https://www.bbc.com/news/technology-24897584
"Microwaves beamed to such a craft would be converted to electricity by special antennas"
https://www.nasa.gov/vision/universe/roboticexplorers/catch_a_microwave.html
"the surface of a rectenna designed to receive microwave energy at a power density of 700 watts per square meter"
https://ntrs.nasa.gov/citations/19900014081