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Conference on Passive Millimetre-Wave and Terahertz Imaging and Technology

作者： Coward, PR Anderton, RN Price, S QinetiQ Malvern WR14 3PS Worcs England

ISBN: (纸本)0819455725

It is well known that the image detected by a camera is only a subset of the information available in a scene. The finite aperture of an optical system leads to a certain amount of diffraction and image blurring, as described by Rayleigh's diffraction criterion. ne image of the scene is then sampled with a finite spatial frequency by the detector(s), be they individual elements in a CCD sensor, light-sensitive cells in the eye, or grains on a photographic film. It is important, when designing a camera system, to ensure that as much of the available image information as possible is collected by the sensor. This involves an analysis of the spatial frequencies that are present in the blurred image, and the design of the image plane detectors in order to best sample the image information. This paper describes the image sampling requirements of millimetre-wave imagers, in particular mechanically scanned imagers that use a conical scanning technique. The trade-off between the requirement to make optimum use of limited image resolution with the high cost of millimetre-wave receiver arrays is considered. Different array layouts used in existing millimetre-wave imagers are presented.

关键词： millimetre-wave imager image sampling receiver array Nyquist sampling

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A 32-Channel Sleeve Antenna receiver array for Human Head MRI Applications at 10.5 T

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IEEE TRANSACTIONS ON MEDICAL IMAGING 2023年第9期42卷 2643-2652页

作者： Woo, Myung Kyun Delabarre, Lance Waks, Matt Lagore, Russell Kim, Jeehoon Jungst, Steve Eryaman, Yigitcan Ugurbil, Kamil Adriany, Gregor Hankuk Univ Foreign Studies Div Biomed Engn Yongin 17035 South Korea Univ Ulsan Sch Elect Engn Dept Biomed Engn Ulsan 44610 South Korea Univ Minnesota Ctr Magnet Resonance Res CMRR Minneapolis MN 55455 USA Case Western Reserve Univ Dept Elect Engn Cleveland OH 44106 USA Cleveland Clin Program Adv Musculoskeletal Imaging PAMI Cleveland OH 44196 USA

For human brain magnetic resonance imaging (MRI), high channel count (=32) radiofrequency receiver coil arrays are utilized to achieve maximum signal-to-noise ratio (SNR) and to accelerate parallel imaging techniques. With ultra-high field (UHF) MRI at 7 tesla (T) and higher, dipole antenna arrays have been shown to generate high SNR in the deep regions of the brain, however the array elements exhibit increased electromagnetic coupling with one another, making array construction more difficult with the increasing number of elements. Compared to a classical dipole antenna array, a sleeve antenna array incorporates the coaxial ground into the feed-point, resulting in a modified asymmetric antenna structure with improved intra-element decoupling. Here, we extended our previous 16-channel sleeve transceiver work and developed a 32-channel azimuthally arranged sleeve antenna receive-only array for 10.5 T human brain imaging. We experimentally compared the achievable SNR of the sleeve antenna array at 10.5 T to a more traditional 32-channel loop array bult onto a human head-shaped former. The results obtained with a head shaped phantom clearly demonstrated that peripheral intrinsic SNR can be significantly improved compared to a loop array with the same number of elements - except for the superior part of the phantom where sleeve antenna elements are not located.

关键词： Antenna arrays Receiving antennas Dipole antennas Magnetic resonance imaging Coaxial cables Signal to noise ratio UHF antennas Dipole antenna magnetic resonance imaging radiofrequency coil receiver array sleeve antenna ultra-high field

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Dedicated receiver array coil for ¹H lung imaging with same-breath acquisition of hyperpolarized ³He and ¹²⁹Xe gas

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MAGNETIC RESONANCE IN MEDICINE 2015年第1期74卷 291-299页

作者： Rao, Madhwesha Robb, Fraser Wild, Jim M. Univ Sheffield Unit Acad Radiol Sheffield S Yorkshire England GE Healthcare Cleveland OH USA

PurposeSame-breath acquisition of H-1 and hyperpolarized gases (He-3 and Xe-129) in the lungs provides complementary information on pulmonary structure and function with inherent spatial-temporal registration of the images from the different nuclei. To date H-1 images have been acquired using the MR system's body coil, which has low SNR when compared with dedicated receiver-array coils. This study demonstrates the design and application of a dedicated H-1 receiver array to improve the H-1 lung SNR for use in same-breath acquisition with hyperpolarized gas He-3 or Xe-129 at 1.5 Tesla. Theory and MethodsA four-loop dedicated receiver-array was developed in-house for H-1 lung MRI to work in compatibility with existing He-3/Xe-129 transmit-receive coils. As part of the design process, a new generalized circuit formalism was developed for trap circuits for such a dedicated H-1 receiver array at 63.8 MHz with traps for He-3 48.6 MHz and Xe-129 17.7 MHz. ResultsThe H-1 lung image SNR from the novel H-1 array was twice that observed with the H-1 body coil when used in same-breath acquisition with the He-3 or Xe-129 T-R coil in situ. ConclusionAn array coil to improve H-1 SNR of the lung in same-breath acquisition with hyperpolarized gases has been demonstrated. Magn Reson Med 74:291-299, 2015. (c) 2014 Wiley Periodicals, Inc.

关键词： receiver array pulmonary lungs hyperpolarized gas

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A numerical model for optimal receiver array and mass flow rate in residential solar water heating systems

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INTERNATIONAL JOURNAL OF SUSTAINABLE ENERGY 2018年第9期37卷 902-918页

作者： Coetzee, Rigardt Alfred Maarten Mwesigye, Aggrey Huan, Zhongjie Tshwane Univ Technol Dept Mech Engn Mechatron & Ind Design Pretoria South Africa Univ Witwatersrand Sch Mech Ind & Aeronaut Engn Johannesburg South Africa

In this paper, the performance of a pressurised evacuated tube solar collector system using internal heat pipes is presented. The system was optimised for the seasonal supply of hot service water for residential use in Pretoria, South Africa. The prediction of seasonal hourly performance trends along with the maximum thermal performance at the optimal receiver array and manifold mass flow rate was of major concern in this investigation. A mathematical model representing the thermal performance of the system was developed and numerically implemented in Engineering Equation Solver. The dynamic performance of collectors with 15, 20 and 25 tubes was determined throughout all the seasons. Moreover, the performance of the residential solar water heating system with a 20-tube collector was investigated in detail for mass flow rates of 0.03, 0.05 and 0.07 kg/s.

关键词： Solar thermal evacuated tube collectors solar water heating heat pipe manifold mass flow rate receiver array

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A fully integrated scanning receiver array

A fully integrated scanning receiver array

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3rd European Radar Conference (EuRAD 2006)

作者： Menzel, Wolfgang Tong, Ziqiang Univ Ulm Microwave Tech PO Box D-89069 Ulm Germany

ISBN: (纸本)9782960055177

In this contribution, an integrated antenna-receiver array is presented. The RF signal is received by open waveguide ports connected to finline mixers. A chain of suspended stripline bandpass fillers is used as LO feed network where phase shifting occurs as a function of frequency. Combining the IF signal in a fixed equal-phase network, the antenna array characteristic is scanned varying the LO frequency from -35 degrees to +35 degrees while the RF frequency is kept constant. The overall very compact arrangement is integrated on a single substrate and placed in a compact metal mount.

关键词： antenna array frequency scanning array receiver array microwave integrated circuits planar filters finline mixers

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Spatially Distributed Polarization receiver array for Communication and Sensing Multifunction Systems 54

Spatially Distributed Polarization Receiver Array for Commun...

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54th European Microwave Conference (EuMC)

作者： Deng, Jie Burasa, Pascal Keivaan, Seyed Ali Wu, Ke Polytech Montreal Poly Grames Res Ctr Montreal PQ Canada

ISBN: (纸本)9798350385892;9782874870774

In this work, a spatially distributed one-dimensional (1-D) receiver array for future polarized multifunction communication and sensing systems is introduced and presented for the first time. Different from the conventional receiver array, the proposed receiver system based on the orthomode transducer (OMT) enables the dual-polarization property without adding the number of receiver blocks. Besides, due to the 1-D spatial distribution, not only does this OMT array significantly improve the communication capacity, but also it can achieve multifunction sensing applications such as typical angle-of-arrival (AoA) and polarization detection. To validate the proposed concept, a theoretical analysis of the proposed receiver array is derived and presented. Then, an experimental 6-cell proof-of-concept prototype is developed, fabricated, and measured. The demodulated 4-QAM and 16-QAM signals confirm the good performance of the proposed OMT receiver array.

关键词： Dual-polarization interferometric techniques multifunction millimeter-wave receiver array sensing system terahertz (THz) wireless communication system

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Optical Communications receiver array

Optical Communications Receiver Array

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Conference on Atmospheric Propagation VII

作者： Saint Clair, Jonathan M. Chan, Eric Y. Koshinz, Dennis G. Wilcken, Stephen K. Soreide, David C. Joshi, Atul Durmus, Hakan Boeing Co POB 3999Mail Code 3W-54 Seattle WA 98124 USA Optimal Aerosp Seattle WA 98115 USA Teledyne Sci Co Thousand Oaks CA 91360 USA

ISBN: (纸本)9780819481498

One of the major challenges to free space laser communications and ladar is the impact of turbulence on beam propagation, one example of which is signal fading. These impacts can be exacerbated on airborne platforms by turbulence in the vicinity of the laser system aperture and the platform wake. There are a number of strategies to mitigate this, including adaptive optics, active flow control, and various dimensions of diversity: wavelength, polarization, temporal, and spatial diversity. In this paper we will discuss spatial diversity implemented in the focal region of optical telescopes. We will briefly compare this with other methods, describe results of requirements analysis of array features and optical configurations for various atmospheric turbulence states, and suggest several attractive configurations. We will also report on the design and test of one configuration, implemented in a prototype, and tested for noise performance, optical transmission, modulation bandwidth, and BER performance with our dynamic turbulence simulator. Early evidence shows significant BER improvements of several orders of magnitude at high turbulence fluctuation frequencies using this technique.

关键词： Atmospheric turbulence communications receiver array lasercom bit error rate turbulence boundary layer spatial diversity

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Acoustic Wireless Power Transfer with receiver array for Enhanced Performance

Acoustic Wireless Power Transfer with Receiver Array for Enh...

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IEEE Wireless Power Transfer Conference (WPTC)

作者： Tseng, Victor Farm-Guoo Bedair, Sarah S. Lazarus, Nathan US Army Res Lab Oak Ridge Associated Univ Fellowship Program Adelphi MD 20783 USA US Army Res Lab Sensors & Elect Devices Directorate Adelphi MD USA

ISBN: (纸本)9781509045853

Achieving wireless power transfer through airborne acoustic/ultrasonic waves has been previously shown to be a feasible alternative when the charging distance is above several times the transducer size. In order to further increase the receiver efficiency, constructing the receiver out of an array of transducer elements to increase the receiver effective area is desirable. In this work, a study on the power combining through series or parallel interconnections of the receiver elements is done to understand the benefits of both cases and the conditions required to maximize receiver efficiency, with measurements and modeling results presented. With a seven element receiver array, a factor of 4.25 increase in receiver efficiency was achieved compared to only using the receiver center transducer.

关键词： Ultrasonic transducers wireless power transfer receiver array power combining acoustic focusing beam steering

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Wideband MMIC receiver modules for imaging array applications 2

Wideband MMIC receiver modules for imaging array application...

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Passive Millimeter-Wave Imaging Technology II

作者： Chu, LY Fischer, E Duncan, SW Byer, NE Weinreb, S Sanders Nashua NH 03061 USA

ISBN: (纸本)0819428272

Recent advances in monolithic semiconductor technology at W-band (75 to 110 GHz) have enabled implementation of compact radiometer front-ends for imaging applications. This paper describes a downconversion approach using Gallium Arsenide (GaAs) monolithic microwave/millimeter-wave integrated circuits (MMIC) to build modules for a 32-element receiver array. The MMIC downconverter module contains low noise amplifiers (LNA), microstrip bandpass filter, Schottky diode mixer and IF amplifiers. In conjunction with the local oscillator (LO), each downconverter serves as a superheterodyne receiver channel in the imaging array. The W-band array has 32 downconverter modules and 8 LO distribution modules which distribute LO power from a Gunn diode oscillator to each downconverter. The LO distribution module incorporates varactor phase shifters with LO drive amplifiers for phase adjustments of +/- 180 degrees to match the phase output from each receiver channel. The downconverter modules of the 32-element array demonstrated >40 dB RF-to-IF gain and an average noise figure of 5.7 dB over a 10 GHz bandwidth centered at 94 GHz. Uniformity of the MMIC devices allows gain tracking within +/-2.5 dB and phase tracking within +/-18 degrees between the 32 receive channels. For Dicke radiometer operation, a PIN diode switch MMIC has been inserted in front of LNA in the downconverter module. Noise figure and gain results for the PIN switch front-end will be presented.

关键词： Gallium Arsenide (GaAs) monolithic microwave/millimeter-wave integrated circuits (MMIC) receiver array downconverter module local oscillator (LO) distribution module

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Long-range measurement system using ultrasonic range sensor with high-power transmitter array in air

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ULTRASONICS 2017年 74卷 186-195页

作者： Kumar, Sandev Furuhashi, Hideo Aichi Inst Technol Dept Elect & Elect Engn 1247 YachigusaYakusa Cho Toyota 4700392 Japan

A long-range measurement system comprising an ultrasonic range sensor with a high-power ultrasonic transmitter array in air was investigated. The system is simple in construction and can be used under adverse conditions such as fog, rain, darkness, and smoke. However, due to ultrasonic waves are well absorbed by air molecules, the measurable range is limited to a few meters. Therefore, we developed a high-power ultrasonic transmitter array consisting of 144 transmitting elements. All elements are arranged in the form of a 12 x 12 array pattern. The sound pressure level at 5 m from the transmitter array was >30 dB higher than that of a single element. A measuring range of over 25 m was achieved using this transmitter array in conjunction with a receiver array having 32 receiving elements. The characteristics of the transmitter array and range sensor system are discussed by comparing simulation and experimental results. (C) 2016 Elsevier B.V. All rights reserved.

关键词： Ultrasonic sensor Range image Transmitter array receiver array Pulse modulation

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