Phased Arrays in Radar and Communication Systems. Pattern Characteristics and Synthesis of Linear and Planar Arrays. Patterns of Nonplanar Arrays. Elements, Transmission Lines, and Feed Architectures for Phased Arrays. Summary of Element Pattern and Mutual Impedance Effects. Array Error Effects. Special Array Feeds for Limited Field of View and Wideband Arrays.

Phased Array Antenna Handbook

The demand for wireless mobile communications services is growing at an explosive rate, with the anticipation that communication to a mobile device anywhere on the globe at all times will be available in the near future. An array of antennas mounted on vehicles, ships, aircraft, satellites, and base stations is expected to play an important role in fulfilling the increased demand of channel requirement for these services, as well as for the realization of the dream that a portable communications device the size of a wristwatch be available at an affordable cost for such services. This paper is the first of a two-part study. It provides a comprehensive treatment, at a level appropriate to nonspecialists, of the use of an antenna array to enhance the efficiency of mobile communications systems. It presents an overview of mobile communications as well as details of how an array may be used in various mobile communications systems, including land-mobile, indoor-radio, and satellite-based systems. It discusses advantages of an array of antennas in a mobile communications system, highlights improvements that are possible by using multiple antennas compared to a single antenna in a system, and provides details on the feasibility of antenna arrays for mobile communications applications.

/pdf/applications-of-antenna-arrays-to-mobile-communications-i-4vrvp7rdiu.pdf

Applications of antenna arrays to mobile communications. I. Performance improvement, feasibility, and system considerations

An antenna arrangement (10) for a cellular radio base station is provided with a plurality of r.f. transceivers, including one or more antenna arrays (12) each comprising a plurality of sub-arrays (20) each selectively operable to form a beam in azimuth. Each sub-array is provided with elevation beamforming means (24) and individual transmit and receive amplifiers (30,32). Each sub-array beamformer is coupled to at least one r.f. transmitter feed (26)nd each r.f. receiver feed is coupled to at least two sub-array beamformers, the sub-arrays of each antenna array together forming a multiplicity of separate substantially coincident beams in azimuth. A method of operation is also disclosed.

Base station antenna arrangement

A surgical instrument that includes a motor-powered drive unit that drives a portion of a firing member assembly in an axial direction to actuate a surgical end effector coupled to the instrument. The instrument may further include a retraction system configured to interact with the firing member assembly to permit a clinician to manually retract the portion of the firing member assembly should it become jammed or inadvertently stopped during a firing process. The surgical instrument includes a locking arrangement that interfaces with the retraction system and the motor-powered drive unit to prevent the transfer of the retraction forces generated by the retraction system to the motor shaft without physically separating portions of the motorized drive unit.

Firing member retraction devices for powered surgical instruments

A plurality of antenna elements on a dielectric substrate are adapted to launch or receive electromagnetic waves in or from a direction substantially away from either a convex or concave edge of the dielectric substrate, wherein at least two of the antenna elements operate in different directions. Slotlines of tapered-slot endfire antennas in a first conductive layer of a first side of the dielectric substrate are coupled to microstrip lines of a second conductive layer on the second side of the dielectric substrate. A bi-conical reflector, conformal cylindrical dielectric lens, or discrete lens array improves the H-plane radiation pattern. Dipole or Yagi-Uda antenna elements on the conductive layer of the dielectric substrate can be used in cooperation with associated reflective elements, either alone or in combination with a corner-reflector of conductive plates attached to the conductive layers proximate to the endfire antenna elements.

Multi-beam antenna

Methods and apparatus for a super-element assembly for a phased array radar aperture, the super-element assembly having a first port and a second port to receive a first signal at the first port to generate a main beam, and receive a second signal at the second port to generate an image beam for generating scan volume coverage using the main and image beams.

Methods and apparatus for volumetric coverage with image beam super-elements

An array antenna system for forming multiple independently steered beams is described. The antenna system includes series or parallel feed circuits and phase shifters which are not disclosed directly in the signal path between the feed circuits and antenna elements included in the array antenna system.

Array antenna having multiple independently steered beams

A low-profile patch radiator for use in an array antenna has a multilayer structure which includes a double-tuned impedance matching network and balun and a coaxial feed for linear polarization of the radiated waves. A second embodiment further includes a second double-tuned impedance matching network and balun and a second coaxial feed for dual polarization operation. The matching networks/baluns, which comprise microstrip circuits on Duroid substrates, increase the frequency bandwidth of the patch radiator.

Patch radiator element with microstrip balian circuit providing double-tuned impedance matching

The design of a novel phase array panel that provides the L-band satellite to ground links for the IRIDIUM global communications system is presented. Key components and aspects of this phase array antenna are discussed including the beamforming architecture, radiated intermodulation products, the patch radiators, and the T/R module. The strategy for minimizing DC power consumption over a large range of multicarrier RF output power is described. Finally, test results showing compliant array operation are summarized.

The IRIDIUM main mission antenna concept

A low array antenna having transmit/receive (T/R) modules, which contain a digitally-controlled variable attenuator, for each of the two polarizations (horizontal and vertical) The array has a cylindrically curved surface which closely conforms to the shape of the fuselage of an airborne vehicle or another structure Each polarization feeds into an elevation beamformer apparatus which provides both a uniform taper and a Bayliss/Taylor taper As the beam is scanned in elevation, the amplitude taper is adjusted via the variable attenuator to control the taper of a sum pattern and thereby achieve low sidelobe far field sum patterns The same attenuators that are used for the sum pattern also feed a difference network The T/R module attenuators are set to yield the desired low sidelobe sum illumination for a desired elevation scan angle As the array is steered in elevation, the Bayliss difference taper is distorted since the fixed elevation beamformer cannot adjust the difference pattern for the new scan angle A T/R module is provided at each column of the array to combine the distorted Bayliss difference pattern with the compensated Taylor sum pattern output This combining permits the distorted Bayliss array illumination to be resymmetrized thereby producing a high quality, low sidelobe, compensated Bayliss far field pattern This apparatus provides for complete compensation of both sum and difference patterns with only a single attenuator at each element of the array and a simple monopulse feed network

Jack J. Schuss

Papers

Methods and apparatus for volumetric coverage with image beam super-elements

Array antenna having multiple independently steered beams

Patch radiator element with microstrip balian circuit providing double-tuned impedance matching

The IRIDIUM main mission antenna concept

Scan compensation for array antenna on a curved surface