Phased array

About: Phased array is a research topic. Over the lifetime, 19428 publications have been published within this topic receiving 229231 citations. The topic is also known as: Phased Array Radar, PAR.

Optical dispersion technique for time-delay beam steering

Abstract: A simple technique for steering the microwave radiation beam of a phased-array antenna is proposed and analyzed. Chromatic dispersion in equal-length fibers is used.

Wideband Radar Cross Section Reduction of Slot Antennas Arrays

Abstract: A comprehensive analysis aimed at reducing the radar cross section (RCS) of array antennas, preserving at the same time their radiating performance, is presented. A microstrip slot array is considered as a test case to illustrate the proposed strategy for radar cross section reduction (RCSR). It is shown that a remarkable reduction of the radar signature can be accomplished over a frequency band as wide as two octaves by employing an array of periodic resistive elements in front of the radiating apertures. The monostatic and bistatic RCS of the proposed structures are investigated both for normal and oblique incidence. Different arrangements and geometries of the periodic resistive pattern are thoroughly analyzed showing the benefits and the drawbacks in terms of antenna gain and level of the scattered fields. Furthermore, the use of metallic parasitic elements for enhancing the antenna gain is considered, and the scattering phenomena caused by their presence are addressed, taking into account the appearance of grating lobes. The antenna designs are also analyzed by resorting to a bidimensional color plot presenting the variation of the reradiated field both in frequency and spatial domain. The guidelines illustrated by the proposed examples can be easily applied to other antenna architectures.

Decoupled Kalman filters for phased array radar tracking

Abstract: Kalman filters have been used in numerous phased array radars to track satellites, reentry vehicles, and missiles. This paper considers the design of these filters to reduce computational requirements, ill-conditioning, and the effects of nonlinearities. Several special coordinate systems used to represent the Kalman filter error covariance matrix are described. These covariance coordinates facilitate the approximate decoupling required for practical filter design. A tutorial discussion and analysis of ill-conditioning in Kalman filters is used to motivate these design considerations. This analysis also explains several well-known phenomena reported in the literature. In addition, a discussion of nonlinearities and methods to mitigate their ill effects is included.

Apparatus for creating hyperthermia in tissue

Abstract: A system and corresponding method for creating hyperthermia in a selected position in target tissue using the application of electromagnetic radiation (EMR) in the HF, VHF and UHF microwave region and phased array steering includes an array of applicators and a single channel EMR radiation energy source coupled to at least one of the applicators of the array. A variable reflective termination device is coupled to at least one of the applicators so that a user can vary the energy radiated from the coupled applicator to steer the heating region in the target to a desired position in the target. Several different applicator arrays are suitable for use with the system, and comprise generally cylindrical annuli which emit radiation toward a central axis. Parasitic applicators with variable reflective termination devices can be used in the applicator array along with at least one applicator directly coupled to the energy source.

A 256-element ultrasonic phased array system for the treatment of large volumes of deep seated tissue

Abstract: A 256-element phased array has been designed, constructed, and tested for ablative treatment of large focal volumes of deep seated tissue. The array was constructed from a 1.1-MHz, 1-3 composite piezoelectric spherical shell with a 10-cm radius of curvature and a 12-cm diameter. The array was tested to determine its electroacoustic efficiency and inter-element coupling under high acoustic power conditions. A series of in vivo porcine experiments demonstrated the ability to produce deep seated tissue lesions in thigh muscle using the large scale phased array. The array was used to heat and coagulate tissue volumes >5 cm/sup 3/ in a single ultrasound exposure using multiple foci and temporally scanned power deposition patterns. The spatial and temporal experimental results for large, heated focal volumes correlated very well with the simulated temperature response model for homogeneous tissue. A 25-cm/sup 3/ tissue volume was coagulated in a 90-min period using overlapping large ultrasound exposures.