What is an antenna? The IEEE Standard Definitions of Terms (IEEE Std 145-1983): ●“A means for radiating or receiving radio waves” "An antenna is any device that converts electronic signals to electromagnetic waves (and vice versa)"effectively with minimum loss of signals,as shown in Fig.1. EM Waves Portion of radio wave intercepted by receiving antenna Transmitting Receiving antenna antenna Transmission Transmission line line Transmitter Receiver Electronic Electronic Figure 1.Wireless communication system.What is an antenna? The IEEE Standard Definitions of Terms (IEEE Std 145-1983):  “A means for radiating or receiving radio waves”  “An antenna is any device that converts electronic signals to electromagnetic waves (and vice versa)” effectively with minimum loss of signals， as shown in Fig.1. Figure 1. Wireless communication system