We report on the development of K-band circulators operating at 20 and 35 GHz which have been monolithically integrated with both GaAs and epitaxial GaAs-on-Si wafers. They demonstrate the potential for a fully integrated T/R module application.

: Studies of magnetostatic wave (MSW) propagation, in epitaxial yttrium iron garnet (YIG) aimed at the development of dispersive delay lines electronically variable delay lines for use in radar and ECM systems are described. Techniques which show the potential for achieving the performance required for systems application of MSW delay lines have been developed. The most pressing problem area is the reduction of amplitude and phase ripple arising from reflections and higher order mode interference to acceptable levels.

: The design, construction and performance of four magnetostatic wave devices operating at X-band is described. They comprise a dispersive delay line with a 1 GHz bandwidth and a differential delay of about 200 nS, a programmable tapped delay line capable of generating and correlating 4-bit Barker codes, a delay stabilized oscillator with output frequency stable to within + or - 1 MHz over the 0 to +65 C range and a 10-channel filter bank.

Using the technique of ’’surface permeabilities,’’ an expression is derived for the dispersion of magnetostatic waves propagating in two close proximity ferrimagnetic films. Two modes of propagation for volume waves are identified respectively as the symmetric and antisymmetric modes from the symmetry of the rf magnetization. Useful group delay behavior is shown to result from films of equal thickness. Some measurements are reported using two yttrium iron garnet films sandwiching simple single finger transducers. Difficulties in exciting the symmetric forward volume mode are explained in terms of the coupling coefficients for these double film structures.

Basic devices required for analog microwave signal processing have been demonstrated using magnetostatic wave propagation in epitaxial yttrium iron garnet films. 100 nsec delay lines with bandwidths of 400 MHz, dispersive delay lines with differential delays of 200 nsec and bandwidths of 1 GHz and a programmable tapped delay line, all operating at S-band through X-band, are described. The operation of a new type of device, a signal-to-noise enhancer or power expander, is discussed which has the opposite characteristic to the more familiar microwave limiter. All these devices share the unique features of operation directly at microwave frequencies and frequency tunability via the strength of the magnetic bias field which is required for their operation.