ABSTRACT
Historically, there are two branches of science that underpin the physics behind electromagnetic fields – electrostatics and magnetism. The ancient Greeks were familiar with electrostatics from their studies of amber and magnetism was known to the Chinese who invented the magnetic compass. Communications, in the form of electromagnetic waves, are literally all around us – radio, TV, mobile phones, Wi-Fi, satellite, etc. One of the problems associated with our innate communication system is that it relies on pressure waves carried by the molecules that make up the air. In order to increase audio power, a microphone can be used to convert sounds into an electrical signal and an amplifier is used to boost the signal. Signals in very high frequency band are quite localized – they are absorbed and scattered by buildings to some extent. The antenna picks up a range of frequencies, for instance the medium-wave band, and these are amplified by the two tuned radio frequency (RF) amplifiers.
