Experimental realisation of micromachined terahertz electromagnetic crystal (EMXT) waveguide bandpass filter

A terahertz (THz) micromachined waveguide bandpass filter based on metallic two-dimensional (2D) electromagnetic crystal (EMXT) with a square lattice is proposed. The filter structure with three dual-mode circular cavities and two rectangular waveguides is obtained by removing and optimising the EMXT unit cells in a 15 × 20 cells array. This filter, fed by WR2.2 waveguides, is fabricated with the silicon microelectromechanical systems technique and measured using a vector network analyser (VNA) with an extender. The measured fractional bandwidth is 7.6% with a 426.5 GHz centre frequency. The best insertion loss and return loss are 2 and 24 dB, respectively. These results agree well with the simulations. The proposed THz EMXT filter indicates a novel approach to obtain THz waveguide passive devices and has application potential in THz communication and detection.