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Abstract-This paper studies the surface modes at the interface of finite size Electromagnetic Band Gap (EBG) woodpile structures. The impact of different types of woodpile terminations on the properties of these surface modes is analyzed. For all the studied terminations there exist surface modes which must be taken into account when designing components based on this EBG structure.

Gap waveguide technology has become an alternative for millimetre and sub-millimetre wave electronic circuit packaging thanks to the loss reduction associated to its use. In this paper a simplified design of an inline transition between microstrip and groove gap waveguide operating at W-band is presented. The transition consists of a tapered microstrip line and a Chebyshev adapter that couple the quasi-TEM mode of the microstrip line to the so-called vertical mode of the groove gap waveguide. The simplicity of this design makes this transition appropriate for MMIC packaging at millimetre frequencies and above. The simulation results have been experimentally validated in the W-band. Good performance has been achieved: return loss better than 10 dB and mean insertion loss lower than 2 dB.

Abstract-This paper presents a novel pyramidal (EH) horn antenna based on Electromagnetic Band Gap structures (EBGs). The reported pyramidal woodpile-based horn antenna possesses a symmetrical radiation pattern and a wide operating frequency range. Such antennas can substitute metallic horns in certain circumstances, which is especially valuable for millimetre and THz devices. The principle of creating EH-horn antennas in the woodpile structure is explained in detail. In particular, this paper presents the design of a symmetrical woodpile EH-horn antenna operating at frequencies around 110 GHz. The reported antenna exhibits a wide operating bandwidth (more than 10%), while possessing high directivity and radiation efficiency equal to 16.35 dBi and −0.55 dB (88%) respectively.