A compact dual‐band coupled‐microstrip‐slotline coupler with arbitrary power division ratios

Abstract

In this paper, a novel dual-band coupler with arbitrary power division ratios using coupled-microstrip-slotlines (CMSLs) is proposed. It consists of only four CMSL sections and occupies a small circuit area due to the centric arrangement of the excitation ports. Different from the microstrip implemented edge-coupled-line, the odd and even modes of the CMSL are physically separated, this feature enables the compensation of their phase velocities, facilitates the control of their characteristic impedances, and reduces the design complexity of the dual-band coupler. Explicit design formula for the proposed coupler is developed. To verify the proposed concept, a dual-band CMSL coupler with an unequal power division ratio is designed and characterized.