Design and Validation of Microstrip Gap Waveguides and Their Transitions to Rectangular Waveguide, for Millimeter-Wave Applications

Abstract

The paper describes the design methodology, experimental validation and practical considerations of two millimeterwave wideband vertical transitions from two gap waveguide versions (inverted microstrip gap waveguide, and microstrip packaged by using gap waveguide) to standard WR-15 rectangular waveguide. The experimental results show S11 smaller than -10 dB over relative bandwidths larger than 25% and 26.6% when Rogers RO3003 and RO4003 materials are used respectively. The vertical transition from standard microstrip line packaged by a lid of pins to WR-15, shows measured return loss better than 15 dB over 13.8% relative bandwidth. The new transitions can be used as interfaces between gap waveguide feed-networks for 60 GHz antenna systems, testing equipment (like Vector Network Analyzers) and components with WR-15 ports, such as transmitting/receiving amplifiers. Moreover, the paper documents the losses of different gap waveguide prototypes compared to unpackaged microstrip line and Substrate Integrated Waveguide (SIW). This investigation shows that in V-band the lowest losses are achieved with inverted microstrip gap waveguide.

A V-Band Inverted Microstrip Gap Waveguide End-Coupled Bandpass Filter

“…Since the wave propagates mainly in the air and surface waves do not exist, the width of the lines in gap waveguides become wider than typical microstrip and SIW. A V-band transition between inverted microstrip gap waveguide and rectangular waveguide was presented and validated with both simulations and measurements in [7]. Measurement results confirmed that the overall loss in inverted microstrip gap waveguide is lower than in conventional microstrip and SIW.…”

“…First, the bed of nails composing the inverted gap geometry must be designed. For this purpose, the same transitions as in [7] have been reused and these dimensions are shown in Fig. 1(a) and Table I.…”

Design of -Band Transition From Microstrip to Ridge Gap Waveguide Including Monte Carlo Assembly Tolerance Analysis

“…However, new versions of gap waveguide transitions are required as the frequency increases. Several suitable transitions working at 60 GHz have been already studied and experimentally validated [12], [13]. In addition, some investigations on transitions between a ridge gap waveguide and standard rectangular waveguides at 0.3 THz have been also initiated.…”

Analysis and design of efficient passive components for the millimeter-wave and THz bands

“…More recently, during 2015 and 2016, from Chalmers, Algaba has presented several advanced transitions [860]- [862]. In [860], a complete work, including design methodology, experimental validation and practical considerations is presented.…”

“…In [860], a complete work, including design methodology, experimental validation and practical considerations is presented. Two transitions are designed: SSGW to WR-15, and microstrip packaged with GW technology (later explained in section 8.2.2.7) to WR-15.…”