Adaptive multibeam antennas for spacelab. Phase A: Feasibility study

The feasibility was studied of using adaptive multibeam multi-frequency antennas on the spacelab, and to define the experiment configuration and program plan needed for a demonstration to prove the concept. Three applications missions were selected, and requirements were defined for an L band communications experiment, an L band radiometer experiment, and a Ku band communications experiment. Reflector, passive lens, and phased array antenna systems were considered, and the Adaptive Multibeam Phased Array (AMPA) was chosen. Array configuration and beamforming network tradeoffs resulted in a single 3m x 3m L band array with 576 elements for high radiometer beam efficiency. Separate 0.4m x 0.4 m arrays are used to transmit and receive at Ku band with either 576 elements or thinned apertures. Each array has two independently steerable 5 deg beams, which are adaptively controlled

A CMOS Digital Beamforming Receiver

As the demand for high speed communication is increasing, emerging wireless techniques seek to utilize unoccupied frequency ranges, such as the mm-wave range. Due to high path loss for higher carrier frequencies, beamforming is an essential technology for mm-wave communication. Compared to analog beamforming, digital beamforming provides multiple simultaneous beams without an SNR penalty, is more accurate, enables faster steering, and provides full access to each element. Despite these advantages, digital beamforming has been limited by high power consumption, large die area, and the need for large numbers of analog-to-digital converters. Furthermore, beam squinting errors and ADC non-linearity limit the use of large digital beamforming arrays. We address these limitations. First, we address the power and area challenge by combining Interleaved Bit Stream Processing (IL-BSP) with power and area efficient Continuous-Time Band-Pass Delta-Sigma Modulators (CTBPDSMs). Compared to conventional DSP, IL-BSP reduces both power and area by 80%. Furthermore, the new CTBPDSM architecture reduces ADC area by 67% and the energy per conversion by 43% compared to previous work. Second, we introduce the first integrated digital true-time-delay digital beamforming receiver to resolve the beam squinting. True-time-delay beamforming eliminates squinting, making it an ideal choice for large-array wide-bandwidth applications. Third, we present a new current-steering DAC architecture that provides a constant output impedance to improve ADC linearity. This significantly reduces distortion, leading to an SFDR improvement of 13.7 dB from the array. Finally, we provide analysis to show that the ADC power consumption of a digital beamformer is comparable to that of the ADC power for an analog beamformer. To summarize, we present a prototype phased array and a prototype timed array, both with 16 elements, 4 independent beams, a 1 GHz center frequency, and a 100 MHz bandwidth. Both the phased array and timed array achieve nearly ideal conventional and adaptive beam patterns, including beam tapering and adaptive nulling. With an 11.2 dB array gain, the phased array achieves a 58.5 dB SNDR over a 100 MHz bandwidth, while consuming 312 mW and occupying 0.22 mm2. The timed array achieves an EVM better than -37 dB for 5 MBd QAM-256 and QAM-512, occupies only 0.29 mm2, and consumes 453 mW.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/147716/1/smjang_1.pd

A methodology to benchmark flexible payload architectures in a megaconstellation use case

International audienceThis paper proposes a methodology to benchmark satellite payload architectures and find the optimal trade-offs between high flexibility and low complexity. High flexibility would enable the satellite to adapt to various distributions of user terminals on the ground and fulfill the data rate demand of these users. Besides, low complexity is required to keep satellite networks competitive in the context of emerging 5G networks. To estimate the flexibility of a payload, an indicator to characterize the non-uniformity of user distributions is proposed. Each benchmarked payload may be characterized by a graph relating the throughput to this parameter further denoted mu. The payload provides the same throughput trends for different scenarios of user distributions with the same mu parameter. As a consequence, the average capacity of the system may be estimated by (a) calculating the probability distribution of mu over the orbit and (b) integrating the throughput based on this payload response. It thus results in a straightforward way for benchmarking payloads directly on an estimation of the averaged capacity, accounting for the user distribution over the earth. A simulation platform has been developed to characterize the payload throughput including the implementation of a resource allocation algorithm that accounts for constraints of various payloads. Using this definition and the developed tool, we benchmark a bent-pipe architecture, a beam hopping architecture and a hybrid beam-steering architecture for a LEO megaconstellation use case. The methodology showcases the interest for investigating different payload architectures depending on realistic traffic scenario analysis

Real-Time Narrowband and Wideband Beamforming Techniques for Fully-Digital RF Arrays

Elemental digital beamforming offers increased flexibility for multi-function radio frequency (RF) systems supporting radar and communications applications. As fully digital arrays, components, and subsystems are becoming more affordable in the military and commercial industries, analog components such as phase shifters, filters, and mixers have begun to be replaced by digital circuits which presents efficiency challenges in power constrained scenarios. Furthermore, multi-function radar and communications systems are exploiting the multiple simultaneous beam capability provided by digital at every element beamforming. Along with further increasing data samples rates and increasing instantaneous bandwidths (IBW), real time processing in the digital domain has become a challenge due to the amount of data produced and processed in current systems. These arrays generate hundreds of gigabits per second of data throughput or more which is costly to send off-chip to an adjunct processor fundamentally limiting the overall performance of an RF array system. In this dissertation, digital filtering techniques and architectures are described which calibrate and beamform both narrowband and wideband RF arrays on receive. The techniques are shown to optimize one or many parameters of the digital transceiver system to improve the overall system efficiency. Digitally beamforming in the beamspace is shown to further increase the processing efficiency of an adaptive system compared to state of the art frequency domain approaches by minimizing major processing bottlenecks of generating adaptive filter coefficients. The techniques discussed are compared and contrasted across different hardware processor modules including field-programmable gate arrays (FPGAs), graphical processing units (GPUs), and central processing units (CPUs)

Multiport beamforming system based on reconfigurable waveguide phased antenna array for satellite communication applications

A multiport K/Ka-band beamforming system based on the reconfigurable waveguide phased antenna array is presented in this thesis. The waveguide structure is used to achieve low loss, wideband performance, and simple installation and maintenance. The antenna array is adopted to compensate for the high propagation loss in higher frequency, which also provided flexible functions for multi-user wireless communication applications. The reconfigurable waveguide transitions are the most crucial component in this beamforming system to achieve dual linear-polarized/left-handed circular-polarized/right-handed circular-polarized functions at K/Ka-band respectively by using the reconfigurable structure. It provided much better performance in bandwidth compared with the recent dual-band/dual-mode waveguide transitions. The waveguide antenna and antenna arrays are reconfigurable and replaceable to meet the design purposes and requirements for linear-polarized/left-handed circular-polarized/right-handed circular-polarized functions. The ultra-bandwidth from K-band to Ka-band provided advantages in saving cost and flexible functions due to the waveguide antenna array parts being applicable for both transmitting/receiving systems for K/Ka-band. This advanced beamforming system could provide many merits such as low loss, wideband, compact structure, high functional flexibility, lower cost, simpler installation, and easier maintenance by using the waveguide reconfigurable. These advantages are indicated by the sufficiently good performance in both the simulated and measured results in this thesis, which demonstrated that this beamforming system design is applicable for wireless communication applications in high frequency, especially for satellite communication applications with separated unlink and downlink systems. The potential and prospect for a MIMO beamforming system with a multilayer PCB feeding network are also demonstrated from the wideband performance of multilayer SICL power divider and SICL-to-waveguide transitions in this thesis to get a more flexible structure for a MIMO beamforming system and more compact structure

小型衛星搭載の合成開口レーダー用の集中型送受信システムを有する２偏波対応進行波型アンテナ

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 齋藤 宏文, 東京大学教授 橋本 樹明, 東京大学教授 保立 和夫, 東京電機大学教授 小林 岳彦, 東京工業大学教授 廣川 二郎University of Tokyo(東京大学

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

Proceedings of the Fifth International Mobile Satellite Conference 1997

Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial communications services. While previous International Mobile Satellite Conferences have concentrated on technical advances and the increasing worldwide commercial activities, this conference focuses on the next generation of mobile satellite services. The approximately 80 papers included here cover sessions in the following areas: networking and protocols; code division multiple access technologies; demand, economics and technology issues; current and planned systems; propagation; terminal technology; modulation and coding advances; spacecraft technology; advanced systems; and applications and experiments

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression