Radio waves and propagation

This chapter discusses properties of radio waves and their propagation. Radio waves are a form of radiation known as electromagnetic waves. The properties of radio waves and the way in which they travel or propagate are of prime importance in the study of radio technology. These waves can travel over vast distances enabling communication to be made where no other means is possible. The communication can be established over distances ranging from a few metres to many thousands of miles. This enables telephone conversations and many other forms of communication to be made with people on the other side of the world using short wave propagation or satellites. Radio waves can be received over even greater distances. Moreover, these waves are quite complicated in their make-up, having both electric and magnetic components that are inseparable. The electric field results from the voltage changes occurring in the antenna which is radiating the signal, and the magnetic field changes result from the current flow. It is also found that the lines of force in the electric field run along the same axis as the antenna, but spreads out as they move away from it.