Realisation of carved and iris groove gap waveguide filter and E-plane diplexer for V-band radio link application

Abstract

The gap waveguide technology is a promising candidate as a cost-effective and low-loss platform for realizing microwave devices particularly at frequencies higher than 40GHz. In this study, two types of groove gap waveguide filters and also a diplexer are presented. Coupling mechanism of these filters is based on carving on the pin plate and iris between adjacent cavities. Two fifth-order Chebyshev filters are realised at 62.5GHz. The proposed diplexer consists of RX and TX iris groove gap waveguide filters at the centre frequency of 59.5 and 62.5GHz and an E-plane groove gap waveguide T-junction. The required transition of the groove gap waveguide to WR-15 is designed and used as an input port of the filters. Moreover, E-plane groove gap waveguide T-junction is designed as the connecting part of the groove gap waveguide filters to the WR-15 antenna port. Finally all parts are integrated. The proposed diplexer is manufactured in aluminium by sawing and milling and then silver plating is done. The RX and TX passbands of the diplexer is around 1.7 and 2.4% with the measured return loss better than 13.6dB and minimum insertion loss of 0.9 and 0.8dB, respectively