Distributed type FET T/R switch

We propose a wideband transmit-receive switch in which a distributed type SPST switch containing only parallel FETs as the distributed circuit elements is combined with the hybrid couplers. The circuit configuration of the switch is explained, the relationship between EET parameters and switch characteristics are found, and test results are described. First, we determine the relationship of bandwidth of the given FETs with the return loss, insertion loss, isolation and rated power of the SPST switch, which is the basic component of transmit/receive switch. Then, applying these relations, the design procedure and design example of SPST switch are given and the possibility of realizing the switch with better bandwidth and rated power characteristics is shown through the calculations using simple equivalent circuits. From the test results, we obtained better insertion loss for more than two octaves. No degradation of performance is seen up to the input power of 28 dBm, and the FETs have no failure even if the input is 33 dBm, which confirms the effectiveness of proposed T/R switch. (C) 1997 Scripta Technica, Inc.