Patent ID: 7068118

Claim:
A pulse modulator for a nonradiative dielectric waveguide, comprising: parallel plate conductors one separated from the other by a distance not greater than one half wavelength of a high frequency signal; a circulator placed between the parallel plate conductors, the circulator including two ferrite plates disposed opposite each other on inner surfaces of the parallel plate conductors, a plurality of mode suppressors, each constructed from a dielectric waveguide for transmitting therethrough an LSM mode electromagnetic wave while shutting off an LSE mode electromagnetic wave, and arranged in such a manner as to extend substantially radially from the two ferrite plates, and an impedance matching member mounted on one end face of each of the mode suppressors and having a dielectric constant different from that of the dielectric waveguide; and a pulse modulation switch constructed from a Schottky barrier diode connected at an intermediate point along a choke-type bias supply line formed on a dielectric wiring substrate, the pulse modulation switch being mounted on the other end face of any one of the mode suppressors in such a manner that a direction of application of a bias voltage to the Schottky barrier diode coincides with a direction of electric field of the LSM mode electromagnetic wave, wherein a distance from an edge of each of the ferrite plates to the Schottky barrier diode is set approximately equal to nλ/2 where n is an integer not smaller than 1, and λ is the wavelength of the high frequency signal.