A Miniaturized Ferrimagnetic High Power Coaxial Duplexer-Limiter

The device to be described in this presentation is a miniaturized high power coaxial component performing within a single package the functions of circulation, power limiting, and preselection. Attention is principally directed to the limiting and preselection functions which are accomplished through the use of a crossed-strip gyromagnetic coupler which differs from those previously reported in that the second-order nonlinear process rather than the first-order process is the basis for its operation. This limiter has been tested independently at power levels as high as 8 kw and found to exhibit a flat leakage output less than 200 mw and a spike leakage energy of about 0.5 erg. The limiter is mechanically tunable over a frequency range greater than 10% in C band. At a fixed setting the 3 db bandwidth is about 20 Mc. The recovery time of the limiter is determined by the kickback of energy from the garnet spin system. Experimental values of this quantity will be presented. The duplexer-limiter package operates at peak powers up to 40 kw into a 2:1 antenna mismatch. Input VSWR at the transmitter port is less than 1.35. Insertion loss from the transmitter port to the antenna port is less than 0.7 db. Low power insertion loss from antenna port through the limiter to the receiver port is 1.0 db.