Semiannual progress report no. 1, 16 November 1964 - 30 June 1965

Summary reports of research in bioelectronics, electron streams and interactions, plasmas, quantum and optical electronics, radiation and propagation, and solid-state electronic

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

Tunable Filters and RF MEMS Variable Capacitors with Closed Loop Control

Multi-band and multi-mode radios are becoming prevalent and necessary in order to provide optimal data rates across a network with a diverse and spotty landscape of coverage areas (3G, HSPA, LTE, etc.). As the number of required bands and modes increases, the aggregate cost of discrete RF signal chains justi es the adoption of tunable solutions. Tunable fi lters are one of the pieces crucial to signal chain amalgamation. The main requirements for a tunable fi lter are high unloaded quality factor, wide tuning range, high tuning speed, high linearity, and small size. MEMS technology is the most promising in terms of tuning range, quality factor, linearity and size. In addition, a fi lter that maintains a constant passband bandwidth as the center frequency is tuned is preferred since the analog baseband processing circuitry tends to be tailored for a particular signal bandwidth. In this work, a novel design technique for tunable fi lters with controlled and predictable bandwidth variation is presented. The design technique is presented alongside an analysis and modeling method for predicting the final filter response during design optimization. The method is based on the well known coupling matrix model. In order to demonstrate the design and modeling technique, a novel coupling structure for stripline fi lters is presented that results in substantial improvements in coupling bandwidth variation over an octave tuning range when compared to combline and interdigitated coupled line fi lters. In order for a coupled resonator filter to produce an equal ripple Chebyshev response, each resonator of the fi lter must be tuned to precisely the same resonant frequency. Production tuned fi lters are routinely tuned in the lab and production environments by skilled technicians in order to compensate for manufacturing tolerances. However, integrated tunable filters cannot be tuned by traditional means since they are integrated into systems on circuit boards or inside front end modules. A fixed tuning table for all manufactured modules is inadequate since the required tuning accuracy exceeds the tolerance of the tuning elements. In this work, we develop tuning techniques for the automatic in-circuit tuning of tunable filters using scalar transmission measurement. The scalar transmission based techniques obviate the use of directional couplers. Techniques based on both swept and single frequency scalar transmission measurement are developed. The swept frequency technique, based on the Hilbert transform derived relative groupdelay, tunes both couplings and resonant frequencies while the single frequency technique only tunes the center frequency. High performance filters necessitate high resonator quality factors. Although fi lters are traditionally treated as passive devices, tunable fi lters need to be treated as active devices. Tuning elements invariably introduce non-linearities that limit the useful power handling of the tunable fi lter. RF MEMS devices have been a topic of intense research for many years for their promising characteristics of high quality factor and high power handling. Control and reliability issues have resulted in a shift from continuously tunable devices to discretely switched devices. However, fi lter tuning applications require fine resolution and therefore many bits for digital capacitor banks. An analog/digital hybrid tuning approach would enable the tuning range of a switched capacitor bank to be combined with the tuning resolution of an analog tunable capacitor. In this work, a device-level position control mechanism is proposed for piezoresistive feedback of device capacitance over the device's tuning range. It is shown that piezoresistve position control is ef ective at improving capacitance uncertainty in a CMOS integrated RF MEMS variable capacitor

The development of a heterodyne receiver at 10.7 THz for the observation of molecular hydrogen

The focus of this thesis is the development of a superconducting hot electron bolometer(HEB) mixer intended for the operation as a heterodyne receiver for the observation of the electric quadrupole transition of molecular hydrogen in space at 10.7 THz. The developed detector is based on a quasi-optical receiver concept using a lens to couple the RF-signal to an antenna. The mixing element is a phonon-cooled niobium nitride microbridge that is integrated in the center of the antenna. The detector consists of a copper tellurium detector block containing the IF-board and IF-connector and the HEB-device glued to the flat backside of the silicon lens. The HEB-device is a circular RF-chip based on a 9 μm thick silicon carrier membrane with the RF-circuit structures and integrated HEB-element on its upper side. For the development of the RF-circuits the dielectric properties of the carrier substrate that consists of high resistivity float zone silicon (HRFZ Si) have been determined since the data available is insufficient for this high frequency range at cryogenic temperatures. The dielectric properties were investigated by means of transmission measurements of different plane parallel silicon samples with two Fourier Transform Spectrometers (FTS) within a frequency range from 4 THz to 18 THz for temperatures between 5 K to 300 K. The measured refractive index increases less than 0.002 with frequency within a frequency interval of 12 THz. From 300 K to 5 K it is reduced by 0.83 % in average. The absorption coefficient of HRFZ Si roughly decreases by 35 % from 300 K to 5 K. The determined permittivity of the carrier substrate at cryogenic operating temperatures of the receiver is 11.4(±0.1). In total 20 different designs of RF-circuits have been developed and fabricated on one wafer by E-beam and UV-lithography technology in the in-house microfabrication facility. The RF-circuits are based on three different broadband antennas and variations of a narrow-band antenna. One narrow-band and one broadband RF-circuit address an operating frequency around 4.7 THz instead of 10.7 THz to enable a comparison with the UpGreat receiver which has been developed in our research group. The broadband antennas are a self-complementary logarithmic, a logarithmic and an Archimedean spiral antenna. The narrow-band antenna is a double-slot antenna of a full effective wavelength in length that is attached to an RF-filter. To investigate the influence of the lens on the antenna beam of the 10.7 THz double-slot antennas a software has been developed and evaluated that is based on a spectral ray tracing technique because the available commercial CST software is not suitable for that task within the present resources and time constraints. According to numerical calculations the double-slot antenna out of the investigated antennas reaches the highest overall coupling efficiency. The predicted Gaussian coupling efficiency without considering losses within the gold layers is 49 % for the designed 4.7 THz double-slot antenna when being mounted at the backside of the silicon lens without an anti-reflection coating. From all broadband antennas the Archimedean spiral antenna that typically is used for distinct lower frequencies below 1 THz, is predicted to obtain the highest overall power coupling to a Gaussian beam of about 39.4 %. Applying an anti-reflection layer on the lens these Gaussian coupling efficiencies are expected to increase to about 64% and 57% for the double-slot antenna and for the Archimedean spiral antenna,respectively. In total five different RF-circuits have successfully been assembled in the detector block and used as an external power detector of an FTS to determine their spectral response within an interval from 3 THz to 12 THz. They are based on three narrow-band designs for 10.7 THz, one narrow-band design for 4.7 THz and a broadband circuit based on the Archimedean spiral antenna. The detectors with the double-slot antennas exhibit a distinct polarization-dependent sensitivity that is maximal at the dedicated polarization direction of the DS-antenna and vanishes for the polarization direction perpendicular to it. All assembled 10.7 THz narrow-band detectors show a response peak slightly below the intended operating frequency with deviations of the center frequencies less than 4 % to 8 %. The measured curves of the RF-response around the operating frequency agree well with the predicted curves of the coupling efficiency between the HEB-element and the antenna. The detector with the Archimedean spiral antenna shows a significant direct response over the entire frequency range from 3 THz to 12 THz. To our knowledge the Archimedean spiral antenna as well as the double-slot antenna till now so far are the only antennas designed for 10.7 THz that have been realized and verified as direct HEB power detectors. The measurement results confirm that these HEB-devices are suitable candidates for future heterodyne measurements. The local oscillator (LO) source that is needed to operate the detectors in heterodyne mode is a Quantum Cascade Laser developed by the Quantum Optoelectronics Group of the IQE, ETH Zurich, and has not yet been completed at the end of this work

Journal of Telecommunications and Information Technology

kwartalni

Proceedings of the 3rd International Conference on Models and Technologies for Intelligent Transportation Systems 2013

Challenges arising from an increasing traffic demand, limited resource availability and growing quality expectations of the customers can only be met successfully, if each transport mode is regarded as an intelligent transportation system itself, but also as part of one intelligent transportation system with “intelligent” intramodal and intermodal interfaces. This topic is well reflected in the Third International Conference on “Models and Technologies for Intelligent Transportation Systems” which took place in Dresden 2013 (previous editions: Rome 2009, Leuven 2011). With its variety of traffic management problems that can be solved using similar methods and technologies, but with application specific models, objective functions and constraints the conference stands for an intensive exchange between theory and practice and the presentation of case studies for all transport modes and gives a discussion forum for control engineers, computer scientists, mathematicians and other researchers and practitioners. The present book comprises fifty short papers accepted for presentation at the Third Edition of the conference. All submissions have undergone intensive reviews by the organisers of the special sessions, the members of the scientific and technical advisory committees and further external experts in the field. Like the conference itself the proceedings are structured in twelve streams: the more model-oriented streams of Road-Bound Public Transport Management, Modelling and Control of Urban Traffic Flow, Railway Traffic Management in four different sessions, Air Traffic Management, Water Traffic and Traffic and Transit Assignment, as well as the technology-oriented streams of Floating Car Data, Localisation Technologies for Intelligent Transportation Systems and Image Processing in Transportation. With this broad range of topics this book will be of interest to a number of groups: ITS experts in research and industry, students of transport and control engineering, operations research and computer science. The case studies will also be of interest for transport operators and members of traffic administration

Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14

Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences