Development of Non-Contacting Type Microwave Rotary Joint for S-Band Radar Application

This paper presents the design of a half wave resonance cavity-based microwave rotary joint which is completely non-contacting and bidirectional in function. The design of rotary joint is such that it consists of two resonant cavities for fixed and rotating section separately connected through a coaxial transmission line section and compactly housed in a mechanical enclosure with through aperture hole. Rotating and fixed sections of rotary joint are separated via suitable bearing and quarter wave chokes for seamless rotation and electrical separation & isolation respectively. Concept is applied to meet the requirement of BITE and LO1 channel transmission from stationary RF exciter set-up to rotatory antenna electronics, hence implemented to design the rotary joint for microwave transmission in the frequency band of 3.1GHz – 3.5GHz (BITE Channel) and 2.5GHz – 2.9GHz (LO1 Channel). The designed rotary joint has been realized and tested for BITE channel with measured results satisfactorily matching the simulations.