Metasurfing since 1987 - a personal story involving soft and hard surfaces, EBG surfaces, cloaking, gap waveguides and mass production

This paper will describe my personal experiences with what today is referred to as metamaterials, and in particular in my case metasurfaces. My journey starts with the introduction of a concept of soft and hard surfaces in 1988, being a generalization of the corrugated surface, and today most conveniently represented by canonical PEC/PMC strip grids. The first industrial application of the soft surface was the patent-protected hat feed in 1987. This has until now been manufactured in more than 940 000 copies mainly for Ericsson´s successful MINILINK product. The anisotropic soft surface is a forerunner of the isotropic EBG surface appearing around year 2000, and the hard surface was used for cloaking 10 years before cloaking became a popular research topic in 2007. The concept of soft and hard surfaces has since 2009 developed into a novel gap waveguide technology. The gap waveguide technology is used to package microstrip and CPW circuits, but also to replace them. The gap waveguides can have similar low-loss performance as solid rectangular waveguides, but they can be realized in a much simpler way in particular at millimeter- and submillimeterwave frequencies. Good performance has been demonstrated for filters, transitions, MMIC packaging, corporate distribution networks, and slot and horn array antennas. The first commercial applications can come soon, probably at 60 GHz.