Antennas

In the last chapter we discussed transmission lines, assuming that each line was terminated in a load. That load was drawn as a lumped circuit, and we did not enquire about its purpose, or its form. In practical systems, a transmission line is often used to connect either a power source to a transmitting antenna, or a receiving antenna to a detecting circuit. Antennas are reciprocal devices, so the ideas we will develop in this chapter apply to both transmitting and receiving systems. However, to avoid unnecessary repetition we will only discuss antennas in the transmitting mode.