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.

Transponder location and tracking system and method

Abstract: A transponder location and tracking system having a phased array antenna mounted at a toll collection station includes a plurality of antenna array elements for receiving a signal from a transponder mounted on a vehicle and for providing a plurality of antenna element electrical signals. A plurality of phase detectors are provided for comparing the phase of the electrical signals to provide a plurality of phase difference signals. A plurality of angle-of-arrival calculation processors is provided for converting the phase difference signals to spatial signals to define the angles-of-arrival of the vehicle transponder signal. A position calculation processor is included for providing an output signal representative of the location of the vehicle in response to the defined angles-of-arrival. In a preferred embodiment, the transponder location and tracking system includes a plurality of receiver processing devices for amplifying and filtering the electrical signals from each antenna element. The phase detectors then compare the phase of the electrical signals to a reference element signal. Each phase detector provides a digital representation of the phase difference signals. The spatial signals represent the angle-of-arrival of the vehicle transponder signal. The position calculation processor operates on the spatial signal to determine the vehicle transponder position. A tracking mechanism is provided to plot the location of a moving vehicle along the roadway.

Demonstration of a continuously variable true-time delay beamformer using a multichannel chirped fiber grating

Abstract: A continuously variable true-time delay beamformer based on a multichannel chirped fiber grating (MCFG) is demonstrated. The beamformer is capable of wide-band squint-free operation and demonstrates beam steering of a four-element array over /spl plusmn/40/spl deg/. The use of an MCFG provides a significant reduction in the length of the chirped grating required, eliminates spurious signal transmission, and utilizes narrow-band tunable laser sources. In addition, the effect of grating errors on the antenna pattern is examined and the tolerance on performance is presented.

A random phased array device for delivery of high intensity focused ultrasound

Abstract: Randomized phased arrays can offer electronic steering of a single focus and simultaneous multiple foci concomitant with low levels of secondary maxima and are potentially useful as sources of high intensity focused ultrasound (HIFU). This work describes laboratory testing of a 1 MHz random phased array consisting of 254 elements on a spherical shell of radius of curvature 130 mm and diameter 170 mm. Acoustic output power and efficiency are measured for a range of input electrical powers, and field distributions for various single- and multiple-focus conditions are evaluated by a novel technique using an infrared camera to provide rapid imaging of temperature changes on the surface of an absorbing target. Experimental results show that the array can steer a single focus laterally to at least ±15 mm off axis and axially to more than ±15 mm from the centre of curvature of the array and patterns of four and five simultaneous foci ±10 mm laterally and axially whilst maintaining low intensity levels in secondary maxima away from the targeted area in good agreement with linear theoretical predictions. Experiments in which pork meat was thermally ablated indicate that contiguous lesions several cm3 in volume can be produced using the patterns of multiple foci.

A Planar Switchable 3-D-Coverage Phased Array Antenna and Its User Effects for 28-GHz Mobile Terminal Applications

Abstract: This paper introduces a planar switchable 3-D-coverage phased array for 28-GHz mobile terminal applications. In order to realize 3-D-coverage beam scan with a simple planar array, chassis surface waves are efficiently excited and controlled by three identical slot subarrays. Three subarrays switch their beams to three distinct regions. Each subarray works as a phased array to steer the beam within each region. Large coverage efficiency is achieved. (e.g., 80% of the space sphere has the realized gain of over 8 dBi.) The proposed antenna covers a bandwidth of over 2 GHz in the band of 28 GHz. User effects on the switchable array are also studied in both data mode and talk mode (voice) at 28 GHz. In talk mode, good directivity and beam switching can be realized by placing the switchable array at the top of the chassis (close to the index finger). And the user shadowing can be significantly reduced by placing it at the bottom of the chassis (close to the palm). In data mode, the switchable array, mounted at the top, achieves less body loss and larger coverage than at the bottom. The proposed antenna is fabricated and measured. The array at the top in talk mode is measured with a real human. The measurements align well with simulations.

Aeroacoustic Phased Array Testing in Low Speed Wind Tunnels

Abstract: This chapter on Aeroacoustic Phased Array Testing in Low Speed Wind Tunnels provides comprehensive coverage of practical aspects for successfully deploying acoustic phased array measurement capability in low-speed wind tunnels. Non-intrusive requirements for acoustic measurement during aerodynamic testing are discussed including array design, construction, and installation. Instrumentation, data acquisition system, and data reduction system requirements are presented. Operational aspects that bring tractability to the demanding challenge of high-channel-count phased array acoustic measurements including calibration techniques, data visibility, and data management are also covered. The author’s broad experience in successfully deploying acoustic phased array measurement technology in several venues including multiple High-Reynolds-Number Wind Tunnels provides proven insights for practicing engineers and advanced students interested in conducting aeroacoustic tests.