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.

An affordable millimeter-wave beam-steerable antenna using interleaved planar subarrays

Abstract: Design and fabrication aspects of an affordable planar beam steerable antenna array with a simple architecture are considered in this paper. Grouping the elements of a phased array into a number of partially overlapped subarrays and using a single phase shifter for each subarray, generally results in a considerable reduction in array size and manufacturing costs. However, overlapped subarrays require complicated corporate feed networks and array architectures that cannot be easily implemented using planar technologies. In this paper a novel feed network and array architecture for implementing a planar phased array of microstrip antennas is presented that enables the fabrication of low-sidelobe, compact, beam-steerable millimeter-wave arrays and facilitates integration of the RF front-end electronics with the antenna structure. This design uses a combination of series and parallel feeding schemes to achieve the desired array coefficients. The proposed approach is used to design a three-state switched-beam phased array with a scanning width of /spl plusmn/10/spl deg/. This phased array which is composed of 80 microstrip elements, achieves a gain of >20 dB, a sidelobe level of 6.3% for all states of the beam. The antenna efficiency is measured at 33-36% in X band. It is shown that the proposed feeding scheme is insensitive to the mutual coupling among the elements.

Photonic RF and microwave reconfigurable filters and true time delays based on an integrated optical Kerr frequency comb source

Abstract: We demonstrate advanced transversal radio frequency (RF) and microwave functions based on a Kerr optical comb source generated by an integrated micro-ring resonator. We achieve extremely high performance for an optical true time delay aimed at tunable phased array antenna applications, as well as reconfigurable microwave photonic filters. Our results agree well with theory. We show that our true time delay would yield a phased array antenna with features that include high angular resolution and a wide range of beam steering angles, while the microwave photonic filters feature high Q factors, wideband tunability, and highly reconfigurable filtering shapes. These results show that our approach is a competitive solution to implementing reconfigurable, high performance and potentially low cost RF and microwave

Dual mode phased array antenna system

Abstract: A phased array antenna system (20) having an array (22) of radiating elements (24-30), such as pyramidal horns, and a distribution network (32) connected thereto, has a dual mode of operation where each mode produces a composite beam which can and preferably does produce an identical far-field electromagnetic radiation pattern. The first composite beam is made up of a plurality of individual beams, forming a linear combination of excitation coefficients (a₁ - a₄) that are mathematically orthogonal to the linear combination of excitation coefficients (b₁ - b₄) of the individual beams of the other composite beam. A plurality of input ports (42-44) are provided, and each composite beam is associated with an information-bearing input signal applied to one of the input ports. The distribution network (32) is preferably constructed with at least two stages of signal-dividing devices such as directional couplers and at least a pair of phase-shifting devices. By using passive devices, the distribution network (32) is substantially lossless and reciprocal, and can thus also be used for dual mode reception of two distinct beams.

Phased array detectors and an automated intensity-correction algorithm for high-resolution MR imaging of the human brain.

Abstract: Two- and four-coil phased array detectors were developed to increase the sensitivity and resolution of MR imaging of the human brain cortex, especially for detecting cortical dysplasias in pediatric epilepsy patients. An automated intensity correction algorithm based on an edge-completed, low-pass filtered image was used to correct the image intensity for the inhomogenous reception profile of the coils. Seven phased array coils were constructed and tested. The sensitivity of these coils was up to 600% higher at the surface of the cortex than that achieved with a conventional head coil and up to 30% greater at the center of the head. The sensitivity obtained was comparable with that of a conventional small surface coil, but extended over the larger dimensions of the array and previously inaccessible areas such as the top of the head. The advantages of the improved sensitivity are demonstrated with high resolution images of the brain.

Overview of frequency diverse array in radar and navigation applications

Abstract: Different from phased array providing only angle-dependent transmit beampattern, frequency diverse array (FDA) employs a small frequency increment across its array elements to provide range-angle-dependent transmit beampattern. This enables the array beam to scan without the need of phase shifters or mechanical steering. Since FDA has received much attention in antenna and radar signal processing societies, it is necessary to make an overview on this interesting topic. This study introduces what FDA is and why it could be exploited for radar and navigation applications from a top-level system description and appeal to the radar signal processing and system engineering communities for more investigations on this promising array technique. The status of FDA studies is overviewed and the most recent advances of FDA radar are discussed. The basic FDA system architectures are introduced, along with performance compared to a conventional phased-array. Next, guidelines for choosing good system parameters and typical implementation schemes are provided. Finally, potential applications in range and angle estimation of targets, cognitive FDA radar and low probability of identification FDA radar are discussed, along with several technical challenges.