Abstract: A high frequency pulse-time modulation (PTM) signal generator employs four or more high frequency oscillators which are mutually locked uniquely either in a symmetric mode or an antisymmetric mode by means of a plurality of electronic phase shifters. The output signals from the oscillators are cascaded together to form a PTM output through control of the electronic phase shifters which shift the mutual locking of the oscillators back and forth between the symmetric and antisymmetric modes. Magic-tees or other combining elements are employed to combine the oscillator output signals so that an output pulse is generated when the oscillators are locked in the symmetric mode and a zero level output is generated when the oscillators are locked in the antisymmetric mode.

Abstract: A high frequency pulse-time modulation signal generator employs first and second microwave or laser oscillators which are mutually locked uniquely either in a symmetric mode or an antisymmetric mode by means of an electronic phase shifter. The output signals from the oscillators are combined to generate pulse-time modulated output pulses through application of a control voltage to the electronic phase shifter which switches the mutual locking of the oscillators back and forth between the symmetric and antisymmetric modes. In a microwave embodiment, a hybrid-tee, such as a magic-tee, is employed to combine the oscillator output signals, while in the optical or laser embodiment, a half-silvered mirror is employed to combine the oscillator output signals. When the oscillators are locked in the symmetric mode, the hybrid-tee generates an output pulse, and when the oscillators are locked in the antisymmetric mode, the hybrid-tee generates a zero level output.

Abstract: A waveguide adaptor or transition for interfacing a microwave waveguide to a coplanar transmission line or electronic device is disclosed. The adaptor includes a waveguide section having an integral coplanar transmission line formed in a longitudinal slot in a top wall thereof. A metallic fin is disposed in the waveguide which extends into the slot. The transmission line is coplanar because the edges of the slot on either side of the fin both act as ground planes. A tapered portion of the fin gradually rises from the bottom surface of the waveguide into the slot which acts as an impedance matching structure between the waveguide and the transmission line. Numerous circuit elements can be connected to the transmission line so that the adaptor can be used to fabricate oscillators, amplifiers, filters and other devices. In particular, a Gunn oscillator formed with the adaptor is disclosed.

Abstract: Dielectric waveguide-to-transmission line transition structures are disclosed which can be used to interface low loss dielectric waveguides with integrated electric circuits for operation in millimeter wave frequency ranges on the order of 100 GHz. Numerous transition designs are presented for interfacing signal propagation in rectangular or cylindrical coplanar metallic transmission lines to signal propagation in dielectric waveguides. In one embodiment of the present invention, a transition structure is provided which includes a first transition section for interfacing a dielectric waveguide to a microstrip transmission line, and a second transition section for interfacing the microstrip transmission line to a coplanar transmission line. In other embodiments of the present invention, the dielectric waveguide interfaces directly to a coplanar transmission line.

Abstract: A waveguide adaptor or transition for interfacing a microwave waveguide to a coplanar transmission line or electronic device is disclosed. The adaptor includes a waveguide section having an integral coplanar transmission line formed in a longitudinal slot in a top wall thereof. A metallic fin is disposed in the waveguide which extends into the slot. The transmission line is coplanar because the edges of the slot on either side of the fin both act as ground planes. A tapered portion of the fin gradually rises from the bottom surface of the waveguide into the slot which acts as an impedance matching structure between the waveguide and the transmission line. Numerous circuit elements can be connected to the transmission line so that the adaptor can be used to fabricate oscillators, amplifiers, filters and other devices. In particular, a Gunn oscillator formed with the adaptor is disclosed.

Abstract: A field-effect transistor (FET) and a corresponding method for its fabrication, the transistor having a source and a gate located at opposite faces of an active channel region formed in a substrate, the source being substantially shorter in effective length than the gate and located symmetrically with respect to the gate. The transistor also has two drains, located one at each end of the channel region, and charge carriers flow from the source to the drains in two paths, under control of the same gate. Electrical contact with the source is made from beneath the substrate, while contact with the gate and drains is made from above. The resulting device has a large incremental transconductance and relatively small parasitic impedances, and therefore can operate at much higher frequencies than conventional FET's.

Abstract: A vector network analyzer system for measuring the complex impedance of devices and components at millimeter wavelengths is disclosed. A pair of directional couplers provide samples of the signal incident on and reflected from the element under test through reference and test channels, respectively. A 180.degree. hybrid, or magic tee, device receives the samples, mixes them vectorially, and produces outputs to two power detectors which provide amplitude and phase information about the complex reflection coefficient. Similar measurements are obtained for the complex transmission coefficient. A 90.degree. phase shifter consisting of a second magic tee and a PIN diode is connected in the reference channel to eliminate a phase measurement ambiguity. A computer processes the power detector output to determine the value of the unknown impedence. An electronically swept signal source allows measurements to be made automatically over a wide frequency band.

Abstract: An IMPATT diode mounted in a double-tuned resonant cavity to exhibit stability by suppressing subharmonic frequencies is disclosed. A foreshortened quarter wavelength section is connected to the diode to form an equivalent parallel resonant circuit at one end thereof. At the other end of the quarter wavelength section is an odd-quarter wavelength tuning slug which provides a section which exhibits a second, series equivalent resonant circuit. To provide increased stability at subharmonic frequencies, a half-wavelength tuning slug is disposed adjacent to the odd-quarter wavelength section. The half wave tuning slug is virtually transparent at the operating frequency, but is a quarter-wavelength at the first subharmonic, and thus exhibits a high resistance at the subharmonic frequency.

Abstract: A microwave and millimeter wave amplifier consisting of a field effect travelling wave transistor monolithically integrated into a coplanar waveguide having input, output and matching sections is disclosed. The amplifier consists of a semi-insulating substrate doped on its upper surface to form within an active region of the device a doping layer of predetermined conductivity type, such as an N type layer. At the lateral edges of the active region the N type material is further doped to produce N+ type regions for receiving source electrodes, while a central part of the active region is similarly doped to produce an N+ type region for receiving a drain electrode. A gate line having a bifurcated terminal end extends into the spaces between the drain electrode and the spaced source electrodes and forms junction contacts with the N type layer in the active region.

Abstract: A solid state integrated circuit type transmission line structure is formed by a semi-conductor substrate consisting of an active layer and a semi insulating layer of given conductivities and permittivity which bears a groove extending through the active layer into the semi insulating layer of the substrate. A thin metalization coating on the active layer surface of the substrate extends into the slot along opposite slot sides thereof, and a low loss dielectric material of different permittivity at least partially fills the slot and extends between the metalization coatings of the slot. There is thus formed a slot line structure and parallel plate transmission line.

Abstract: A field-effect transistor (FET) and a corresponding method for its fabrication, the transistor having a source and a gate located at opposite faces of an active channel region formed in a substrate, the source being substantially shorter in effective length than the gate and located symmetrically with respect to the gate. The transistor also has two drains, located one at each end of the channel region, and charge carriers flow from the source to the drains in two paths, under control of the same gate. Electrical contact with the source is made from beneath the substrate, while contact with the gate and drains is made from above. The resulting device has a large incremental transconductance and relatively small parasitic impedances, and therefore can operate at much higher frequencies than conventional FET's.