0 dB coupler employing slot technique on planar microstrip

Abstract

Realization of crossovers is always a problem in the design of microwave integrated circuits. In many cases, when a high isolation between crossing strips is required in a rather large frequency band, it is preferable to avoid a trivial separation of the strips by a dielectric layer. This paper focuses on designing and developing a wideband 0 dB coupler on planar microstrip. in In this paper, the proposed 0 dB coupler is designed using square patch with slotted lines. To compare the performances of the proposed design, a conventional 0 dB coupler using double section branch line coupler is presented as well. A substrate Rogers RO4003C with dielectric constant of 3.38 and thickness of 0.508 mm at center frequency 2.4 GHz are used in both designs. They are compared in terms of the size, and their s-parameter performance. Both couplers developed with the aid of design tool CST Microwave Studio and fabricated using microstrip technology.