A filter-based NRD-guide duplexer with low-loss and high-isolation for wireless broad-band asymmetric digital subscriber line at 60GHz

A filter-based duplexer having low-loss and high-isolation performance was developed for a wireless broad-band asymmetric digital subscriber line by using NRD guide technology at 60 CHz. Emphasis was placed on rigidity of the circuit configuration. The duplexer consists of a junction circuit and low-loss ceramic resonators. The junction circuit, made by a mode transformer between an NRD guide and a vertical strip line, provided good rigidity and well halanced output levels as well as small insertion loss. The NRD guide band-pass filter using circular ceramic resonators embedded in a thin Teflon sheet has good advantages such as low insertion loss in a pass band and sharp skirt cutoff nature in rejection bands. The NRD guide duplexer was fabricated by assembling them. The isolation between a transmitter port and a receiver port was measured to he more than 45 dB, and besides, the insertion loss was measured to he less than 3 dB in the 60 GHz baud.