Abstract: A hardware-only contactless position sensor system is provided that includes a contactless position sensor and hardware-only sensor system electronics. The sensor includes excitation, sine, and cosine coils. The electronics are coupled to the sensor and detect a position of a target relative to the sensor. The electronics include a phase shift and summation circuit that applies a phase shift at a frequency of the excitation coil to one of a sine signal from the sine coil or a cosine signal from the cosine coil as a phase shifted signal and add the phase shifted signal with an unshifted instance of the cosine or sine signal to produce a phase shifted output. The electronics also include a phase detector circuit that detects a phase of the phase shifted output and generate an output voltage corresponding to the phase and proportional to the position of the target.

Abstract: In one example, a patch antenna includes a conductive ground plane layer, a conductive circular patch layer, a dielectric layer, a grounding connection, and a RF feed. The conductive circular patch layer includes a plurality of voids. The dielectric layer is disposed between and contacts each of the ground plane layer and the circular patch layer. The grounding connection extends from the ground plane layer through the dielectric layer and contacts the circular patch layer at a grounding location of the circular patch layer. The RF feed extends through the ground plane layer and the dielectric layer and contacts the circular patch layer at a RF feed location of the circular patch layer. The RF feed location is offset from a central axis of the circular patch layer.

Abstract: In one example, a patch antenna includes a conductive ground plane layer, a conductive circular patch layer, a dielectric layer, a grounding connection, and a RF feed. The conductive circular patch layer includes a plurality of voids. The dielectric layer is disposed between and contacts each of the ground plane layer and the circular patch layer. The grounding connection extends from the ground plane layer through the dielectric layer and contacts the circular patch layer at a grounding location of the circular patch layer. The RF feed extends through the ground plane layer and the dielectric layer and contacts the circular patch layer at a RF feed location of the circular patch layer. The RF feed location is offset from a central axis of the circular patch layer.

Abstract: A hardware-only contactless position sensor system is provided that includes a contactless position sensor and hardware-only sensor system electronics. The sensor includes excitation, sine, and cosine coils. The electronics are coupled to the sensor and detect a position of a target relative to the sensor. The electronics include a phase shift and summation circuit that applies a phase shift at a frequency of the excitation coil to one of a sine signal from the sine coil or a cosine signal from the cosine coil as a phase shifted signal and add the phase shifted signal with an unshifted instance of the cosine or sine signal to produce a phase shifted output. The electronics also include a phase detector circuit that detects a phase of the phase shifted output and generate an output voltage corresponding to the phase and proportional to the position of the target.

Abstract: A phase shifter for and a method for shifting phase in an antenna configured to emit a radio signal at a wavelength include a transmission line. The transmission line has a length along a primary axis and a width across a secondary axis. The primary axis and secondary axis intersect to define a waveguide plane. A conductive screen layer has first and second screen surfaces. The screen surfaces are substantially planar and disposed parallel to and spaced apart from the waveguide plane by a distance and are spaced apart from each other by a screen thickness much smaller than a skin depth of the screen layer determined at the wavelength. A dielectric layer envelopes the screen layer and has a first dielectric surface residing substantially in the waveguide plane and a second dielectric surface parallel to and spaced apart from the first dielectric surface by a height greater than the distance.

Abstract: A monolithic integrated circuit for performing power dividing and power monitoring functions is disclosed. The monolithic integrated circuit includes a power dividing portion for dividing radio frequency (RF) signal power and a power monitoring portion for monitoring the RF signal power. In one example, the monolithic integrated circuit is a microwave monolithic integrated circuit (MMIC) for use in high-frequency applications within microwave and millimeter-wave frequency range.

Abstract: Imaging methods and systems for concealed weapon detection are disclosed. In an active mode, a target can be illuminated by a wide-band RF source. A mechanically scanned antenna, together with a highly sensitive wide-band receiver can then collect and process the signals reflected from the target. In a passive mode, the wide-band receiver detects back-body radiation emanating from the target and possesses sufficient resolution to separate different objects. The received signals can then be processed via a computer and displayed on a display unit thereof for further analysis by security personnel.

Abstract: Imaging methods and systems for concealed weapon detection are disclosed. In an active mode, a target can be illuminated by a wide-band RF source. A mechanically scanned antenna, together with a highly sensitive wide-band receiver can then collect and process the signals reflected from the target. In a passive mode, the wide-band receiver detects back-body radiation emanating from the target and possesses sufficient resolution to separate different objects. The received signals can then be processed via a computer and displayed on a display unit thereof for further analysis by security personnel.

Abstract: A proximity sensor having a generator providing a signal of which a small portion is used as a reference signal and the remaining portion is radiated out towards a target. The radiation reflected from the target is equalized and/or normalized relative to the reference signal. The signals are compared in terms of relative phase relationship. This relationship implies the distance of the target from an antenna. An example target may be a rail wheel. A certain part of the wheel is measured in terms of distance from the sensor. This distance may determine wheel wear. Such wear is gauged relative to a threshold signal or reference distance. Also, speed and direction of the rail wheel can be determined from the signal reflected back to the proximity sensor.

Abstract: A varactor diode having a stepped capacitance-voltage profile, formed in heterostructural integrated circuit technology. Several layers in the diode structure have pulse doping to confine conduction in the diode to a sheet of charge that provides the stepped capacitance-voltage profile. The structural design of the diode may be modified to attain desired capacitance-voltage characteristics.

Abstract: A voltage-controlled oscillator (VCO) especially designed for use in the millimeter wave frequency band (Ka-band) and which exhibits an adjustable tuning sensitivity. A low tuning sensitivity is easily obtained, making it suitable for narrow-band FMCW applications. It comprises a Gunn diode as a negative resistance device and a voltage variable capacitance diode (varactor) as a tuning element. A fixed capacitance element is coupled in RF series with the varactor and microstrip transmission lines are configured to function as impedance matching, resonating and filtering elements. By incorporating the fixed capacitance in RF series with the varactor, the tuning sensitivity, measured in volts/Hz is markedly reduced. The VCO uses a novel RF structure which puts the fixed capacitance in RF series with the varactor, without introducing the fixed capacitance element in the varactor bias circuitry.

Abstract: A microstrip oscillator utilizing a Gunn diode as its active element for operation in the W-Band. A microstrip shunt resonator is dimensioned to resonate the Gunn diode at either its fundamental frequency or second harmonic frequency while a matching circuit, including a quarter wavelength transformer and a coupled microstrip transformer is employed to match the complex impedance of the Gunn diode device to the load. A radial hat on the Gunn diode effectively prevents radiation of electromagnetic energy from the system to thereby maximize the energy delivered to the load while, at the same time, functioning as a transformer element.

Abstract: A planar varactor tuned microstrip oscillator for Ka band operation comprising a GaAs Gunn diode, a varactor diode, an impedance inverter microstrip line placing the varactor in shunt with the Gunn diode, an impedance matching transformer connected from the output of the Gunn diode to a load connection means, a source of negative bias potential for the varactor and a source of positive bias potential for the Gunn diode.