Control of mode-switching in an active antenna using MESFET

New techniques of realizing mode-switching in an active antenna by using a MESFET are presented. Two types of control circuits are discussed. One is the control circuit using the reactance variation of the MESFET and the other is the control circuit using the resistance variation of the MESFET. The design of these two control circuits is discussed and the beam-switching phenomena of the antenna using these control circuits are compared. Important characteristics such as antenna patterns, operating frequencies and the insertion loss of the control circuits are also compared and discussed.<
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