Phase shift module

About: Phase shift module is a research topic. Over the lifetime, 10896 publications have been published within this topic receiving 98916 citations.

Synthetic aperture radar

Abstract: PURPOSE: To enhance the resolution without sacrificing the image quality by additionally providing a plurality of sub-apertures, hybrid synthetic units and phase shifters and providing two systems of transmitter, receiver and A/D converter. CONSTITUTION: An antenna is divided into four sub-apertures 1-4, each of which is provided with a different phase thus producing two transmission/receiving beams. In other words, four sets of hybrid synthetic units 5, 6, 9, 10 are combined with a 90° phase shifter 78 to produce two beams. At the time of transmission, power is fed from transmitters 13, 15 through circulators 11, 12 to the sub-apertures 1-4. At the time of receiving, analog output signals from receivers 14, 16 are converted through A/D converters 17, 18 into digital data which are then subjected through a signal processing circuit 19 to range compression and frequency synthesis before being imaged through synthetic aperture processing. In other words, two beams are employed in the observation in order to widen the observation band or enhance the resolution per one look thus obtaining a high resolution image. COPYRIGHT: (C)1996,JPO

Optical phased array technology

Abstract: Optical phased arrays represent an enabling new technology that makes possible simple affordable, lightweight, optical sensors offering very precise stabilization, random-access pointing programmable multiple simultaneous beams, a dynamic focus/defocus capability, and moderate to excellent optical power handling capability. These new arrays steer or otherwise operate on an already formed beam. A phase profile is imposed on an optical beam as it is either transmitted through or reflected from the phase shifter array. The imposed phase profile steers, focuses, fans out, or corrects phase aberrations on the beam. The array of optical phase shifters is realized through lithographic patterning of an electrical addressing network on the superstrate of a liquid crystal waveplate. Refractive index changes sufficiently large to realize full-wave differential phase shifts can be effected using low (<10 V) voltages applied to the liquid crystal phase plate electrodes. High efficiency large-angle steering with phased arrays requires phase shifter spacing on the order of a wavelength or less; consequently addressing issues make 1-D optical arrays much more practical than 2-D arrays. Orthogonal oriented 1-D phased arrays are used to deflect a beam in both dimensions. Optical phased arrays with apertures on the order of 4 cm by 4 cm have been fabricated for steering green, red, 1.06 /spl mu/m, and 10.6 /spl mu/m radiation. System concepts that include a passive acquisition sensor as well as a laser radar are presented.

Variable-phase-shift-based RF-baseband codesign for MIMO antenna selection

Abstract: We introduce a novel soft antenna selection approach for multiple antenna systems through a joint design of both RF (radio frequency) and baseband signal processing. When only a limited number of frequency converters are available, conventional antenna selection schemes show severe performance degradation in most fading channels. To alleviate those degradations, we propose to adopt a transformation of the signals in the RF domain that requires only simple, variable phase shifters and combiners to reduce the number of RF chains. The constrained optimum design of these shifters, adapting to the channel state, is given in analytical form, which requires no search or iterations. The resulting system shows a significant performance advantage for both correlated and uncorrelated channels. The technique works for both transmitter and receiver design, which leads to the joint transceiver antenna selection. When only a single information stream is transmitted through the channel, the new design can achieve the same SNR gain as the full-complexity system while requiring, at most, two RF chains. With multiple information streams transmitted, it is demonstrated by computer experiments that the capacity performance is close to optimum.

Coherent solid-state LIDAR with silicon photonic optical phased arrays

Abstract: We present, to the best of our knowledge, the first demonstration of coherent solid-state light detection and ranging (LIDAR) using optical phased arrays in a silicon photonics platform. An integrated transmitting and receiving frequency-modulated continuous-wave circuit was initially developed and tested to confirm on-chip ranging. Simultaneous distance and velocity measurements were performed using triangular frequency modulation. Transmitting and receiving optical phased arrays were added to the system for on-chip beam collimation, and solid-state beam steering and ranging measurements using this system are shown. A cascaded optical phase shifter architecture with multiple groups was used to simplify system control and allow for a compact packaged device. This system was fabricated within a 300 mm wafer CMOS-compatible platform and paves the way for disruptive low-cost and compact LIDAR on-chip technology.

A New Class of Broad-Band Microwave 90-Degree Phase Shifters

Abstract: In the type of circuits considered here, the input power is divided equally between two channels whose outputs are caused to have a very nearly 90° phase difference over a broad frequency range. Networks suitable for application at low frequencies which perform the above function have been widely investigated. This report describes a new type of 90° differential phase shifter which has a constant resistance input, and which is useful over bandwidths as large as 5:1 in the microwave region.