Abstract
Rectangular waveguide is known for its ability to propagate microwave signals with low loss in a wide range of microwave and millimetre-wave applications. Recent developments in these applications have focussed particularly on integration of different circuits and miniaturisation of modules; rectangular waveguide requires expensive fabrication methods and is replaced wherever possible with planar transmission lines. However, these have much higher losses. This research has investigated the feasibility of several low cost methods of fabricating dielectric-filled rectangular waveguide. The methods used are based on multichip module (MCM) technology. The technologies used to fabricate the waveguides are multichip module laminate (MCM-L) and multichip module ceramic (MCM-C) processes. In the MCM-L method, a PCB milling machine technique was used with PCB laminates designed for a multilayer process. With the MCM-C technology, two material types are used to fabricate dielectric-filled waveguide using multilayer thick film processing. The materials used are the photoetchable and photoimageable thick film pastes. The photoimageable thick film process was successfully used to fabricate H-plane offset waveguide filters. LTCC processing using Green Tape materials was also investigated for the dielectric-filled rectangular waveguide fabrication. The MCM-L and photoetchable thick film dielectric filled rectangular were fabricated in- house, whilst the photoimageable waveguide was fabricated by Hibridas as part of a collaborative project. The performances were tested using TRL calibration on the VNA, and a range of transitions, guides, and filters have been evaluated, including a 160-170 GHz bandpass filter. Key words: Dielectric-filled rectangular waveguide, MCM technology, photoetchable and photoimageable thick film technology, LTCC.