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9
Microwave Antennas
9.1 Introduction
Antennas (or aerials) are devices that radiate (or couple) electromagnetic
energy into space. Their effectiveness depends on their ability to concentrate
(or direct) the energy into the desired direction. An efcient antenna is one
in which very little or no energy is lost in the radiation process. The trans-
mitting and receiving antennas have similar characteristics and in many
applications, a single antenna is used to perform both the functions. As most
of the radars and communication systems operate in microwave range, the
antennas used in these applications are referred to as microw ...