Interdigital-Pin Groove Gap W-Band Waveguide Filter

In this paper, the design and realization of an interdigital-pin groove gap waveguide filter in W-band is discussed. The groove gap waveguide technology has proven to be suitable for the realization of passive components up to high frequencies. However, the overall structure including pin width and pin distance becomes smaller for higher frequencies, which increases manufacturing difficulties. Especially the pin distance defines the manufacturing costs and effort with respect to the computerized numerical control (CNC) milling approach, which is often used for fabrication. The interdigital-pin groove gap waveguide approach is therefore applied, increasing the maximal allowed cutter diameter compared to standard groove gap waveguide technique. The design and realization of a third order W-band (75GHz-110GHz) groove gap waveguide filter is discussed and potential approaches for further reducing the manufacturing effort are proposed.

I. Introduction

Gap waveguide components were first introduced in [1]. They usually consist of two parts: a periodic pin structure, providing the electromagnetic functionality as well as a flat cover. In comparison to the well-known waveguide components, the pin structure and the flat cover do not have any contact with each other. Therefore, a potential Q-factor reduction due to imperfect material transitions as in the case of commonly known waveguide components is avoided. This additionally reduces the risk for passive intermodulation due to gaps between two waveguide halves [2]. The gap can also be used for the integration of additional components.