Pulse modulator for nonradiative dielectric waveguide, and millimeter wave transmitter/receiver using the same

A millimeter wave transmitter/receiver, comprising:

• a pair of parallel plate conductors one separated from the other by a distance not greater than one half wavelength of a millimeter wave signal to be transmitted;
• a first dielectric waveguide for propagating the millimeter wave signal therethrough;
• a millimeter wave signal oscillator, attached to the first dielectric waveguide, for generating the millimeter wave signal using a high frequency generating device, and for propagating the millimeter wave signal into the first dielectric waveguide;
• a second dielectric waveguide whose one end is electromagnetically coupled by proximity to the first dielectric waveguide, or is joined to the first dielectric waveguide, thereby propagating a portion of the millimeter wave signal into a mixer;
• a pulse modulator for a nonradiative dielectric waveguide, including:
• a first circulator constructed with 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, the first circulator having a function of directing the millimeter wave signal inputted from one of the mode suppressors, into another one of the mode suppressors that is adjacent in clockwise or counterclockwise direction in a plane of the ferrite plates, and
• a pulse modulation switch comprising a dielectric wiring substrate, a choke-type bias supply line formed on the dielectric wiring substrate, and a Schottky barrier diode connected to an intermediate point of the choke-type bias supply line,
• wherein the first dielectric waveguide is connected to a first mode suppressor of the plurality of mode suppressors of the first circulator at a position on the downstream side, as viewed in signal propagation direction, of a signal coupling portion where the portion of the millimeter wave signal is coupled into the second dielectric waveguide, and
• the pulse modulation switch is mounted on the farthest end face of a second mode suppressor of the plurality of mode suppressors of the first circulator 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, and that the distance from an edge of the ferrite plates to the Schottky barrier diode is approximately equal to nλ/2 where n is an integer not smaller than 1, and λ is the wavelength of the high frequency signal;
• a second circulator constructed with two ferrite plates disposed opposite each other on the 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 the dielectric constant of the dielectric waveguide, the second circulator having a function of directing the millimeter wave signal inputted from one of the mode suppressors, into another one of the mode suppressors that is adjacent in clockwise or counterclockwise direction in the plane of the ferrite plates, wherein one of the plurality of mode suppressors of the second circulator is a third mode suppressor of the plurality of mode suppressors of the first circulator;
• a transmitting/receiving antenna, connected to a fourth mode suppressor of the plurality of mode suppressor of the second circulator, for propagating the millimeter wave signal therethrough for transmission or reception of the millimeter wave signal, the fourth mode suppressor being another one of the plurality of mode suppressors of the second circulator;
• a third dielectric waveguide for propagating into the mixer a received wave received by the transmitting/receiving antenna, propagated through the fourth dielectric waveguide, and outputted from a fifth mode suppressor of the plurality of mode suppressor of the second circulator, the fifth mode suppressor being another one of the plurality of mode suppressors in the second circulator;
• and
• a mixer section for generating an intermediate frequency signal by mixing the portion of the millimeter wave signal with the received wave, the mixer section being constructed by electromagnetically coupling an intermediate portion of the second dielectric waveguide by proximity to an intermediate portion of the third dielectric waveguide or by joining the second and third dielectric waveguides together,
• wherein the first dielectric waveguide, the millimeter wave signal oscillator, the second dielectric waveguide, the pulse modulator, the second circulator, the third dielectric waveguide, and the mixer section are arranged between the parallel plate conductors.

A millimeter wave transmitter/receiver, comprising:

• a pair of parallel plate conductors one separated from the other by a distance not greater than one half wavelength of a millimeter wave signal to be transmitted;
• a first dielectric waveguide for propagating the millimeter wave signal therethrough;
• a millimeter wave signal oscillator, attached to the first dielectric waveguide, for generating the millimeter wave signal using a high frequency generating device, and for propagating the millimeter wave signal into the first dielectric waveguide;
• a second dielectric waveguide whose one end is electromagnetically coupled by proximity to the first dielectric waveguide, or is joined to the first dielectric waveguide, thereby propagating a portion of the millimeter wave signal into a mixer;
• a pulse modulator for a nonradiative dielectric waveguide, including:
• a circulator constructed with 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, the circulator having a function of directing the millimeter wave signal inputted from one of the mode suppressors, into another one of the mode suppressors that is adjacent in clockwise or counterclockwise direction in a plane of the ferrite plates, and
• a pulse modulation switch comprising a dielectric wiring substrate, a choke-type bias supply line formed on the dielectric wiring substrate, and a Schottky barrier diode connected to an intermediate point of the choke-type bias supply line,
• wherein the first dielectric waveguide is connected to a first mode suppressor of the plurality of mode suppressors of the circulator at a position on the downstream side, as viewed in signal propagation direction, of a signal coupling portion where the portion of the millimeter wave signal is coupled into the second dielectric waveguide, and
• the pulse modulation switch is mounted on the farthest end face of a second mode suppressor of the plurality of mode suppressors of the circulator 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, and that the distance from an edge of the ferrite plates to the Schottky barrier diode is approximately equal to nλ/2 where n is an integer not smaller than 1, and λ is the wavelength of the high frequency signal;
• a transmitting antenna, connected to a third mode suppressor of the plurality of mode suppressors of the circulator, for propagating the millimeter wave signal therethrough for transmission of the millimeter wave signal;
• a third dielectric waveguide having a receiving antenna at an end portion thereof and the mixer at the other end;
• and
• a mixer section for generating an intermediate frequency signal by mixing the portion of the millimeter wave signal with the received wave, the mixer section being constructed by electromagnetically coupling an intermediate portion of the second dielectric waveguide by proximity to an intermediate portion of the third dielectric waveguide or by joining the second and third dielectric waveguides together,
• wherein the first dielectric waveguide, the millimeter wave signal oscillator, the second dielectric waveguide, the pulse modulator, the third dielectric waveguide, and the mixer section are arranged between the parallel plate conductors.