Abstract: A stripline tuning fork microwave balanced mixer circuit which includes two diodes (21, 22) and a differential transformer (61) whereby matching is accomplished in the differential transformer (61) and in the circuit arrangement between the differential amplifier and the diodes (21, 22) for matching the resistance to the input terminals (1, 2) and a transforming circuit (24, 25, 26) which suppresses the frequency range of the input signals following the diodes and has simultaneous high frequency blocking for matching to the intermediate frequency signal output at terminal (3). This latter circuit can be utilized so that it functions as a blocker for the sum frequencies of the two input signals and the balanced push-pull mixer circuit of the invention can be used in sensitive receivers used in the microwave range.

Abstract: A P-I-N type diode high frequency switch in a secondary radar interrogation device working with ISLS and RSLS and consisting of a transmitter, two receivers and two antennas. So as to reduce the high cost for P-I-N type diodes, including driver stages for the transmission and reception separation and to eliminate the necessity of an antenna switching unit, the terminals 19 and 20 of a pair of antennas are directly connected through single lines 23 and 24 to band pass filters 5 and 6 connected to respective receivers 7 and 8 with the band pass filters 5 and 6 blocking the transmission signal and allowing reception of received signals and wherein the electrical lengths of the line and the band pass filter is such that the input impedance corresponding to no-load operation occurs at the corresponding antenna terminal for the transmission frequency.