A 170–260 GHz CPW to Waveguide Contactless Transition Using Interdigital-pin EBG Structure

A broadband coplanar-to-rectangular waveguide transition using contactless electromagnetic bandgap (EBG) structure in the form of interdigital-pin bed of nails is introduced in this paper. The electromagnetic (EM) wave propagates from the CPW, and then radiates from the probe into the WR4. The rectangular patch is adopted as the probe to accomplish a broadband performance without an impedance transformer. The presented transition has 41.8% fractional bandwidth, which covers the whole WR4 band (170-260GHz). The insertion loss is less than 0.47dB. In addition, the interdigital-pin EBG structure is added to the machining splitter of the rectangular waveguide which is no need for strict electrical contact. The greatest advantage of the interdigital-pin lattice has a significant pin gap increase and is easy to fabricate for millimeter-wave (mm-Wave) applications.

I. Introduction

With the development of millimeter-wave (mm-Wave) technology in modern wireless communication systems, mmWave hybrid integrated circuits and monolithic integrated circuits have been widely used in communications, radar, guidance and other systems. Coplanar Waveguide (CPW) is an important transmission line in the mm-Wave integrated circuit which has the advantages of small dispersion, low loss and easy to realize the series and parallel of passive and active devices [1]. However, rectangular waveguides are currently adopted as input and output ports for many mainstream mmWave measurement systems and devices. Therefore, the wideband transition design from CPW to rectangular waveguide is necessary in millimeter wave circuits and systems.