Chapter 14 Antenna Basics
Note: This chapter is a reworked version of the column “The darker side: Antenna basics,” Circuit Cellar, no. 211, February 2008.
Any RF communication system needs a pair of antennas. What is an antenna? It is simply a device that transforms an electric wave, coming from a generator with a given impedance, into a radiated electromagnetic wave that will propagate in free space or will reciprocally transform an electromagnetic wave into an electric wave to a receiver. Because it is difficult to transmit power over the air, an antenna designer wants reasonable power efficiency in the transmission. To do this, you need to take care of two things: the electric and the electromagnetic sides of the transmission: