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Waveguide-type semiconductor integrated circuits (ICs) in gaps between conducting surfaces with texture – architecture, electromagnetic modeling and micromachining

Final Report Summary - GAPWAVE ICS (Waveguide-type semiconductor integrated circuits (ICs) in gaps between conducting surfaces with texture – architecture, electromagnetic modeling and micromachining)

The gap waveguide (GW) technology is a disruptive one which displaces the conventional waveguide and microstrip line technologies at millimeter wave (mmW) and terahertz regime, especially in the applications of high gain planar array antennas, waveguide filters and integration of large RF systems, with low manufacture cost, low ohmic loss, easy integration with MMICs and scalability over frequencies. The idea of the GW technology is the utilization of two parallel plates with one of PEC (perfect electrical conductor) and the other of PMC (perfect magnetic conductor) so that there is no wave propagation allowed in between them as long as the spacing between the plates is smaller than a quarter wavelength. Introducing some wave guiding mechanism, such as a groove waveguide, a ridge or inverted microstrip line, in the parallel plates, the wave propagation can be controlled to realize different functionalities to build up RF chains or systems for wireless communication system, sensor systems or other systems.

In this ERC project, the concept has been solidly proved with simulations and measurements, and the theory, the analysis methods, the numerical methods and the design procedures for the GW technology have been established. The realization of the PMC plate has been achieved by several means, such as full-height pin, via holes, patches with vias and half-height pins, providing alternatives for different manufacturing techniques with low cost. From the technical perspective, the success of this ERC project has been reflected in the following aspects. 1) Gapwave flanges and twists for connecting waveguides have better performance than traditional waveguide flanges and twists with much easier and faster assembly; 2) Gapwave filters has relaxed manufacturing requirements with good performance; 3) Gapwave planar array antennas have achieved the highest efficiency among all types of antennas at mmW frequencies with low cost; 4) New idea and concept of gapwave technology have been proposed, such as the half-height pin gap waveguide technology and SWE (Sheet Waveguide Element) antennas, as extensions to the original GW technology and also inspired other researchers to propose a new research area called gliding symmetry geometry gapwave technology; 5) A GW calibration kit for measuring devices and antennas at mmW has been realized, which avoids the drawbacks of the existing GSG probe calibration kit; 6) GW technology has provided a new integration method of antennas and devices at mmW to MMICs. A planar antenna system at E-band with diplexer has been integrated with Tx and Rx on MMIC circuitries; 7) GW technology has been applied to realize grid amplifiers with a potential to high power transmitters at mmWs. 8) GW packaging has high isolation, low loss and flexibility without resonance compared to existing technology by using absorber in the closed cavity.

The success of this ERC project has already been recognized by scientific societies. In total, 8 best student paper awards have been received by the PhD students involved in this project, 5 invited talks on GW technology given by Prof. Kildal and Prof. Yang in conferences and workshops, 1 convened session on GW technology at a well-known international conference held with the presentations of 10 researchers over the world in 2017.

The success of the project is also reflected by the fact that 6 PhD students have been supported by the project and 4 of them have got their PhD degrees, and two are finishing their PhD study.

This ERC project is very successful in transferring the knowledge and IPs (intellectual properties) created during the project to industry and creating new jobs. 1 industry entrepreneur award has been received by Prof. Kildal. 7 patent applications have been filed and transferred to different companies. A spin-off company from the research team, Gapwaves AB in Gothenburg, Sweden, has been successfully listed in First North Nasdaq in 2016, and now has about 20 employees.