Abstract: A SAW device tapped delay line includes an apodized input IDT (inter-digital transducer) and a plurality of substantially identical unapodized output IDTs arranged to receive, after delays which successively increase by an amont T, a SAW propagated from the input IDT. Each output IDT is terminated with a low impedance which is constituted by the low input impedance of a buffer amplifier, to minimize acoustic regeneration by the output IDTs. Grounded dummy fingers with the same metallization ratio as the output IDTs are provided between adjacent output IDTs to provide a constant SAW velocity. The delay line is particularly suited to use in an equalizer of a microwave radio transmission system, in which the delay T is the inverse of the symbol rate of the system. Intermediate frequency automatic time domain equalizer (IF ATDE) arrangements using the SAW device tapped delay line are described.

Abstract: A dielectric resonator microwave bandpass filter includes a printed circuit board supported within a cut-off waveguide, with dielectric resonators and coupling loops on an upper surface of the board and a well beneath the board so that the resonators are well spaced from ground planes. Tuning screws beneath the resonators, and coupling adjustment screws above the board adjacent to the coupling loops and between adjacent resonators, provide for adjustments to provide desired filter characteristics within a wide range. Isolators within the waveguide have ports coupled to the resonators via microstrip transmission lines comprising conductive tracks on the board and ports coupled to coaxial connectors in end walls of the waveguide. The waveguide is formed from a cast body and a flat lid.