HIGH-FREQUENCY CIRCUIT DEVICE AND COMMUNICATION APPARATUS HAVING SPURIOUS MODE PROPAGATION BLOCKING CIRCUIT

摘要

Electrodes are formed on both top and bottom surfaces of a dielectric plate and grounded coplanar lines, as transmission lines, are formed on the top surface of the dielectric plate. A plurality of micro-strip lines, each composed of high-impedance lines and low-impedance lines alternately connected in series, is arranged at a pitch shorter than the wavelength of a wave traveling along the grounded coplanar lines. A spurious mode propagation blocking circuit thus constructed prevents a spurious mode wave, such as a parallel-plate mode, from traveling.