New low loss inverted microstrip line using gap waveguide technology for slot antenna applications

Recently, a new transmission line concept, called gap-waveguide, has been introduced. This technology generates a quasi-TEM mode in the gap between parallel metal plates and prohibits all other modes to propagate by making use of artificial magnetic conductors (AMCs) in the forms of e.g. lid of nails or mushrooms-type EBG surfaces. It has been shown how such geometry can replace standard microstrip lines and waveguides since it needs neither dielectric nor metal joints, being then an advantageous alternative that can be used for several applications at high frequency. This paper shows how the gap waveguide can also be realized in printed technology creating a new type of inverted microstrip line, called microstrip gap waveguide, which has low loss and large bandwidths can be achieved.