Printed circuit radial power combiner with mode suppressing resistors

Abstract

A power splitter/combiner includes a radial waveguide and a coaxial common port coupled to the center of the radial waveguide. The radial waveguide has a plurality of transmission lines around its periphery at equally spaced locations. Because of its symmetry, the power at each of the peripheral transmission lines is related to the power at the common port in proportion to the number of peripheral transmission lines. For operation at high frequencies, the radial waveguide, the transmission lines and the transition from radial waveguide to the transmission lines have their structural details defined by a printed circuit (PC) board having a low temperature dielectric material. The PC board includes a plurality of radial slots to control undesired circumferential modes. A resistance arrangement is coupled across the open end of each radial slot to dissipate circumferential power. The resistance arrangement includes a copper ring including a like number of radial slots, and at least one thick-film resistor fired at high temperature onto the ring near the open end of each radial slot. A bond wire couples each thick film resistance arrangement across its associated slot. The ring with fired-on resistors is bonded at low temperature onto the printed circuit board with radial slots in the ring registered with the radial slots on the printed circuit board.