Substrate integrated waveguide negative-order resonances and their applications

Abstract

A family of substrate integrated waveguide (SIW) negative-order resonances and their applications to miniaturised antennas and filters are investigated and presented. These metamaterial resonators are realised by etching the interdigital slot on the surface of SIW with varied boundary conditions. The slot acts as a series capacitor along with the waveguide inherent shunt inductor achieving a composite right/left-handed functionality. These resonances are generated below the characteristic waveguide cut-off frequency and are independent of the dominant TE10 mode. The properties of these different resonances, which are characterised by half-wavelength or quarter-wavelength resonances, are discussed and compared. According to their characteristics, different applications are investigated. First, miniaturised waveguide slot antennas based on the first-order resonance are discussed. These antennas provide relatively high radiation efficiency and regular radiation patterns while keeping a low profile. Secondly, compact waveguide filters are proposed and presented. The simulated and measured results for these filters are provided. These metamaterial filters are showing advantages in terms of low-profile, high stopband rejection, easy fabrication and integration with other circuits.