Abstract: Low-profile radar reflectors are provided for reradiating when illuminated by a vertically-polarized incident wave generated by an automotive radar. One example reflector includes a ground plane, a substrate having a top surface and a bottom surface, and radiating elements positioned on the substrate. Each radiating element includes opposing vertical metallic side segments connected to the ground plane, and a horizontal metallic segment extending between the opposing vertical metallic side segments and along the top surface of the substrate. The horizontal metallic segment of each radiating element has a defined length such that, when the radiating element is illuminated by a vertically-polarized incident wave from an automotive radar, each radiating element is at its resonance causing currents in the opposing vertical metallic side segments to flow in the same direction and reradiates back to the automotive radar.

Abstract: A real-time automotive radar simulation tool is developed based on reduced statistical models summarized from physical-based asymptotic and full-wave simulations. Some models have been verified with measurements. The simulation tool can help save cost and time for the automotive industry, especially for autonomous vehicles. The simulation tool can also help develop new functionalities like target identification or classification as well as help prevent false alarms.

Abstract: In one aspect, a system and method for aligning hip replacement prostheses comprises an acetabular liner having an inner concave surface and an outer convex surface. The acetabular liner includes at least two magnetic sensors arranged in a spatially distributed manner. The system and method also include a prosthetic femoral component comprising a femoral head component. The femoral head component and the acetabular liner component are shaped such that a ball and socket joint is formed when the femoral head component comes into contact with the inner concave surface of the acetabular liner. While the ball-and-socket joint is formed, and in at least some orientations of the femoral head component relative to the acetabular liner component, a contact point on an external surface of the femoral head component contacts the inner concave surface. The femoral head component includes at least one permanent magnet.

Abstract: A dual-polarized antenna is presented for 5G mobile communications. The antenna includes two discrete elements—a folded dipole and a folded monopole, which generate two orthogonal polarizations. Parasitic elements are used to realize higher-band operation. In one example, the antenna covers both the 28 GHz band and the 39 GHz band. The entire structure is designed on an ultra-thin four-layer laminate and is intended to be incorporated along the edges of smartphones to enable 5G operation.

Abstract: All existing state-of-the-art high resolution millimeter wave imaging systems experience a trade off between image acquisition time and transceiver array complexity. The proposed dual reflector antenna breaks this trade-off by drastically reducing the array formation time while maintaining the relative simplicity that comes with using a single transceiver element. It consists of a dual mode horn feed, a rotating ellipsoidal sub-reflector and a conic main reflector. The rotating sub-reflector creates a virtual phase center that rotates about an axis to produce a synthetic circular array with a diameter of 120?. The main reflector redirects the beams from each of these virtual phase centers to overlap and illuminate the scene over a wide field of view. The proposed system can reduce the image acquisition time to the order of milliseconds/seconds which makes real-time SAR imaging a practical alternative to MIMO and phased arrays at millimeter-wave and sub-millimeter-wave frequencies.

Abstract: A subsurface imaging technique using distributed sensors is introduced. Instead of monostatic transceivers employed in conventional ground penetrating radars, the proposed technique utilizes bi-static transceivers to sample the reflected signals from the ground at different positions and create a large two-dimensional aperture for high resolution subsurface imaging. The coherent processing of the samples in the proposed imaging method eliminates the need for large antenna arrays for obtaining high lateral resolution images. In addition, it eliminates the need for sampling on a grid which is a time-consuming task in imaging using ground penetration radar. Imaging results show that the method can provide high-resolution images of the buried targets using only samples of the reflected signals on a circle with the center at the transmitter location.

Abstract: A two-port antenna system is proposed that uses a polarization-independent spatial power divider to align the beams from two orthogonally oriented dual-polarized feeds. This antenna system is compatible with fully polarimetric radar and provides high port isolation. It simultaneously provides a common aperture for transmit and receive to minimize radar parallax. The spatial power divider is designed using a combination of all-dielectric metamaterial techniques and the concept of miniaturized-element frequency selective surfaces, and is fabricated on a silicon wafer using standard microfabrication technology.

Abstract: An active matching network for impedance matching to a miniature antenna, comprising a cross-coupled transistor pair, where each transistor has an emitter, base and collector, the emitter of a first transistor forms an input terminal, the emitter of a second transistor forms on output terminal, the collector of the first transistor coupled to the base of the second transistor, the collector of the second transistor coupled to the base of the first transistor, and a matching circuit coupled between the collectors of the first and second transistors. The matching network is configured to match an impendence near resonance of the high Q miniature antenna to an input impedance using a complex negative impedance comprising resistance, inductance and capacitance.

Abstract: A dual-polarized antenna is presented for 5G mobile communications. The antenna includes two discrete elements—a folded dipole and a folded monopole, which generate two orthogonal polarizations. Parasitic elements are used to realize higher-band operation. In one example, the antenna covers both the 28 GHz band and the 39 GHz band. The entire structure is designed on an ultra-thin four-layer laminate and is intended to be incorporated along the edges of smartphones to enable 5G operation.

Abstract: A two-port antenna system is proposed that uses a polarization-independent spatial power divider to align the beams from two orthogonally oriented dual-polarized feeds. This antenna system is compatible with fully polarimetric radar and provides high port isolation. It simultaneously provides a common aperture for transmit and receive to minimize radar parallax. The spatial power divider is designed using a combination of all-dielectric metamaterial techniques and the concept of miniaturized-element frequency selective surfaces, and is fabricated on a silicon wafer using standard microfabrication technology.

Abstract: An antenna system includes a ground and a substrate mounted on the ground. The antenna system includes a first transmitter antenna and a second transmitter antenna configured to transmit a first signal at a predetermined frequency. The first transmitter antenna has a first longitudinal axis and is mounted in a first quadrant of the substrate. The second transmitter antenna has a second longitudinal axis and is mounted in a second quadrant of the substrate. The antenna system includes a first receiver antenna and a second receiver antenna configured to receive a second signal at the predetermined frequency. The first receiver antenna has a third longitudinal axis and is mounted in a third quadrant of the substrate. The third longitudinal axis of the first receiver antenna is oriented orthogonal to the first longitudinal axis of the first transmitter antenna and the second longitudinal axis of the second transmitter antenna.

Abstract: A broadband, dual-polarized, cavity-backed slot antenna (CBSA) array is presented for enabling full-duplex wireless communication. The antenna consists of a thin rectangular cavity appropriately loaded with metallic septa to excite multiple resonances of similar desired field distribution to achieve consistent radiation characteristics over a wide bandwidth. Four pairs of orthogonal radiating slots are cut out on one of the broad-walls of the cavity; all of which are fed by two orthogonal slots on the opposite broad-wall of the cavity. The cavity is fed by an end-launch coaxial-to-waveguide transition to excite one of the channels. The other channel is excited by a two-pronged microstrip line symmetrically crossing over the other cavity feeding slot. Due to the out-of-phase coupling from the two prongs of the microstrip line to the other port, this type of excitation is shown to provide an unpredicted level of isolation between the two channels over a wide bandwidth.

Abstract: An active matching network for impedance matching to a miniature antenna, comprising a cross-coupled transistor pair, where each transistor has an emitter, base and collector, the emitter of a first transistor forms an input terminal, the emitter of a second transistor forms on output terminal, the collector of the first transistor coupled to the base of the second transistor, the collector of the second transistor coupled to the base of the first transistor, and a matching circuit coupled between the collectors of the first and second transistors. The matching network is configured to match an impendence near resonance of the high Q miniature antenna to an input impedance using a complex negative impedance comprising resistance, inductance and capacitance.

Abstract: In one aspect, a system and method for aligning hip replacement prostheses comprises an acetabular liner having an inner concave surface and an outer convex surface. The acetabular liner includes at least two magnetic sensors arranged in a spatially distributed manner. The system and method also include a prosthetic femoral component comprising a femoral head component. The femoral head component and the acetabular liner component are shaped such that a ball and socket joint is formed when the femoral head component comes into contact with the inner concave surface of the acetabular liner. While the ball-and-socket joint is formed, and in at least some orientations of the femoral head component relative to the acetabular liner component, a contact point on an external surface of the femoral head component contacts the inner concave surface. The femoral head component includes at least one permanent magnet.

Abstract: A subsurface imaging technique using distributed sensors is introduced. Instead of monostatic transceivers employed in conventional ground penetrating radars, the proposed technique utilizes bi-static transceivers to sample the reflected signals from the ground at different positions and create a large two-dimensional aperture for high resolution subsurface imaging. The coherent processing of the samples in the proposed imaging method eliminates the need for large antenna arrays for obtaining high lateral resolution images. In addition, it eliminates the need for sampling on a grid which is a time-consuming task in imaging using ground penetration radar. Imaging results show that the method can provide high-resolution images of the buried targets using only samples of the reflected signals on a circle with the center at the transmitter location.

Abstract: A broadband, dual-polarized, cavity-backed slot antenna (CBSA) array is presented for enabling full-duplex wireless communication. The antenna consists of a thin rectangular cavity appropriately loaded with metallic septa to excite multiple resonances of similar desired field distribution to achieve consistent radiation characteristics over a wide bandwidth. Four pairs of orthogonal radiating slots are cut out on one of the broad-walls of the cavity; all of which are fed by two orthogonal slots on the opposite broad-wall of the cavity. The cavity is fed by an end-launch coaxial-to-waveguide transition to excite one of the channels. The other channel is excited by a two-pronged microstrip line symmetrically crossing over the other cavity feeding slot. Due to the out-of-phase coupling from the two prongs of the microstrip line to the other port, this type of excitation is shown to provide an unpredicted level of isolation between the two channels over a wide bandwidth.

Abstract: A real-time automotive radar simulation tool is developed based on reduced statistical models summarized from physical-based asymptotic and full-wave simulations. Some models have been verified with measurements. The simulation tool can help save cost and time for the automotive industry, especially for autonomous vehicles. The simulation tool can also help develop new functionalities like target identification or classification as well as help prevent false alarms.

Abstract: An antenna system includes a ground and a substrate mounted on the ground. The antenna system includes a first transmitter antenna and a second transmitter antenna configured to transmit a first signal at a predetermined frequency. The first transmitter antenna has a first longitudinal axis and is mounted in a first quadrant of the substrate. The second transmitter antenna has a second longitudinal axis and is mounted in a second quadrant of the substrate. The antenna system includes a first receiver antenna and a second receiver antenna configured to receive a second signal at the predetermined frequency. The first receiver antenna has a third longitudinal axis and is mounted in a third quadrant of the substrate. The third longitudinal axis of the first receiver antenna is oriented orthogonal to the first longitudinal axis of the first transmitter antenna and the second longitudinal axis of the second transmitter antenna.

Abstract: A borehole drilling communication system that includes a hydraulic drill, a communication module, and a transducer. The hydraulic drill has a drill pipe and a drill head where the communication module is located, The transducer has an input end and is mounted on the drill pipe adjacent the communication module. The communication module includes a first output terminal electrically connected to the drill pipe and a second output terminal electrically connected to the input end of the transducer. The transducer includes a helical conductor that is positioned coaxially over a section of the drill pipe at the drill head, with the helical conductor terminating at an electrically isolated free end. During use in borehole drilling, data sent from the communication module is launched by the transducer and transmitted along the drill pipe as a single conductor transmission line.

Abstract: A matching technique and the field enhancement at the terminals of a bowtie nanoantenna is presented to develop compact, highly efficient, and flexible thermophotovoltaic (TPV) cells. The bowtie antenna is designed for maximum power transfer to a near infrared band of a TPV cell. In one example, a small cube of indium gallium arsenside antimode or another suitable material with a low bandgap energy of 0.52 eV is mounted at the terminals of the antenna. Such a load presents a frequency dependent impedance with a high resistance and capacitance at the desired frequency (180THz). For maximum power transfer, a high impedance bowtie antenna operating at the anti-resonance mode connected to an inductive transmission line to compensate for the load capacitance is realized. The same antenna and load configuration with the semiconductor material used in photoconductive mode is used to realize a sensitive uncooled photodetector.