ABSTRACT
Transmitting antenna and Receiving antenna behave identically i.e., their behaviour is reciprocal. The phenomenon of using the same antenna for transmission as well as for reception is called Antenna Reciprocity. A transmitting antenna or aerial can be considered as an open circuited transmission line. The space around the line may be considered as load with complete mismatch conditions. This line (antenna) radiates signal in the form of e.m. waves. The length of antenna should be some multiple of the wave length of the applied RF energy. This is, because the antenna must present itself as a resonant circuit to the RF signal so as maximise power in the antenna. The components of the line produce capacitive and inductive effects. The effective length of the antenna therefore increases. The transmitting antenna radiates signal energy in the form of em waves which travel through the layers of the “ionosphere”. The radiation changes with season and also with day and night.
