Fundamentals of the Interactions of Radio Frequency and Microwave Energies with Matter

Abstract

A relatively large segment of the electromagnetic spectrum is occupied by radio-frequencies (RF) and microwaves (MW). The lower part between a few tens of kilohertz (kHz) and 300 megahertz (MHz) is called radio-frequencies, while the upper part between 300 MHz and 300 gigahertz (GHz) is named microwaves. The corresponding wavelengths extend from a few tens of kilometres (km) to 1 metre (m) for radio-frequencies and from 1 m to 1 millimetre (mm) for microwaves. The quantum energies at these frequencies are very small and not capable of altering the intramolecular structure nor breaking any intermolecular bonds. The maximum quantum energy (at 300 GHz) is 1.2 × 10⁻³ electronvolt (eV), while a disruption of the weekest hydrogen bond requires 0.08 eV, for comparison, the thermal motion energy at 30°C is 2.6 × 10⁻² eV.