HIGH UNIFORMITY MICROSTRIP TO MODIFIED-SQUARE-AX INTERCONNECT

A very low reflection transition with tightly controlled variability between a rectangular coaxial transmission line and a microstrip transmission line. The microstrip ground plane is extended under the transition region to form the transition ground plane. The upper portion of the dielectric of the rectangular coaxial transmission line is removed at the transition region, together with the upper portion of the center conductor. The spacing between the transition center conductor and the ground plane is reduced in relation to the spacing between the rectangular coaxial line center conductor and outer conductive shield. A tuning cavity is formed in the transition ground plane beneath the transition center conductor.