Gap waveguides and PMC packaging: Octave bandwidth mm- and submm-wave applications of soft & hard surfaces, EBGs and AMCs

AMCs, EBGs and other surface-based metamaterials are known to have narrow bandwidths. However, when they are used to generate stopbands for parallel-plate modes, the bandwidth can be very large. This characteristic is used in the gap waveguide technology that was invented in 2008, based on old research on soft and hard surfaces. The gap waveguide technology can be used to package microstrip and CPW circuits, but can also with advantage replace such standard technologies and in particular above 30 GHz. The gap waveguides can have similar lowloss performance as solid rectangular waveguides, but they can be realized in a much better way. Rectangular waveguides are normally realized by split blocks which are screwed tightly together to ensure good conductive contact, whereas gap waveguides can be realized between parallel plates without metal connection. This paper overviews how the gap waveguide technology has been explored during the passed five years including: demonstrations of the wideband lowloss guiding characteristics up to 260 GHz, demonstrations of packaging in different frequency ranges with different AMCs or EBGs, and demonstrations of filters, transitions, MMIC packaging, corporate distribution networks, and slot and horn array antennas. The technology demonstrators cover the three different versions of gap waveguides: groove gap waveguide, ridge gap waveguides and microstrip gap waveguides.