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Assessment and Performance of Flexible Quench Antenna Array Diagnostics for Superconducting Magnets
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An analysis of simultaneous beam formation by means of passive scattering matrices and uniform planar antenna arrays
Simultaneous beam formation by passive scattering matrices and uniform planar arrays
[Studies in the 11 Meter Range of Radio Astronomy Using High Resolution and High Sensitivity Antenna Arrays at Clark Lake]
Interplanetary scintillation observations from solar wind inhomogeneities
Improved circularly polarized planar-array antenna
Slots sitting astride the virtual wall in a multimode wave guide can be used for generation of one component of a circularly polarized beam. There is a high degree of efficiency without the use of a slow-wave structure.
Wide-angle, circularly polarized, omnidirectional-array antenna
Modified conventional turnstile antenna features bifoliate pattern with relatively high gain and good circularity over solid area enclosed by the 0.26 and 1.31 radian angles of elevation. These antennas are intended for high altitude balloon use, their permissible weight is restricted to one pound.
Economical phased-array antenna for environmental applications
Antenna system handles data acquisition and tracking, functions as a sensitive radio telescope, and serves as a radiometer in earth atmosphere investigations. Antenna's sensitivity permits resolution of solar disk quadrants in Doppler radar observations. Antenna also serves as a planetary radar device and link to commercial aircraft.
Subcarrier signal combiner for arrayed antennas
Quadrature correlation for automatic signal phasing and variable delay is used to combine signals for improved signal-to-noise ratio.
System implications of large radiometric array antennas
Current radiometric earth and atmospheric sensing systems in the centimeter wavelength range generally employ a directive antenna connected through a single terminal pair to a Dicke receiver. It is shown that this approach does not lend itself to systems with greatly increased spatial resolution. Signal to noise considerations relating to antenna efficiency force the introduction of active elements at the subarray level; thus, if Dicke switching is to be used, it must be distributed throughout the system. Some possible approaches are suggested. The introduction of active elements at the subarray level is found to ease the design constraints on time delay elements, necessary for bandwidth, and on multiple beam generation, required in order to achieve sufficient integration time with high resolution.
System implications of large radiometric array antennas
Temperature sensitivity degradation due to antenna losses is recognized as a hindrance to extension of available remote-sensing radiometry techniques to larger systems for enhanced spatial resolution. The use of large antennas is also complicated by difficulties with bandwidth and integration time. Advantages of introducing active devices at the subarray level, with distributed Dicke switching or correlation detection, are examined, and their possible contribution to the design of effective imaging microwave radiometers for remote sensing of geophysical parameters (sea state, distribution of sea ice, cloud types and their distributions, soil moisture) is assessed.
Design and fabrication of microstrip antenna arrays
A microstrip array project was conducted to demonstrate the feasibility of designing and fabricating simple, low cost, low sidelobe phased arrays with circular disk microstrip radiating elements. Design data were presented for microstrip elements and arrays including the effects of the protective covers, the mutual interaction between elements, and stripline feed network design. Low cost multilayer laminate fabrication techniques were also investigated. Utilizing this design data two C-band low sidelobe arrays were fabricated and tested: an eight-element linear and a sixty-four element planar array. These arrays incorporated stripline Butler matrix feed networks to produce a low sidelobe broadside beam.
Prediction of antenna array performance from subarray measurements
Computer runs were used to determine the effect of mechanical distortions on array pattern performance. Subarray gain data, along with feed network insertion loss, and insertion phase data were combined with the analysis of Ruze on random errors to predict gain of a full array.
Virtual-Center Antenna-Arraying System
Separate signals averaged to produce reference frequency and phase. System develops reference carrier from separate received signals. Phase of signal at each receiver determined by comparison with reference phase. Useful in applications requiring accurate phase estimates: reception of weak telemetry signals, transmitter or reflector locating, nondestructive testing of structures, or geophysical exploration.
MMIC devices for active phased array antennas
The study of printed circuit discontinuities is necessary in order to design, for example, transitions between rectangular waveguides and printed circuits. New developments with respect to the analytical approaches to this problem are discussed. A summary of the progress in the experimental approach is presented. The accurate solution for the modes in various millimeter-wave waveguides is essential in the analysis of many integrated circuit components, such as filters and impedance transformers. Problems associated with the numerical computation of these modes in two frequently used waveguide forms, namely, the finline and microstrip, are presented. The spectral domain method of formulation, with a moment method solution, is considered. This approach can be readily extended to analyze an arbitrary configuration of dielectric and metallized regions in a shielded enclosure. Galerkin's method is used, where the testing and basic functions are the same. It is shown that the mode functions, or eigenfunctions, are more sensitive to errors than the phase constants, or eigenvalues. The approximate mode functions do not satisfy the orthogonality relationship well, resulting in difficulties when these modal solutions are used to form an approximate Green's function or are used in a mode matching analysis.
MMIC devices for active phased array antennas
Considerable progress has been made in the calculation and measurement of the scattering parameters of printed circuit discontinuities. These discontinuities occur in a variety of structures, such as transitions between rectangular waveguide and printed circuits, junctions between circuits of different dielectric constants, and filters and impedance matching circuits. Because of the variety of devices in which these discontinuities occur, it is very useful to understand them in as great a detail as possible. Both theoretical and experimental studies of discontinuities were considered. The theoretical studies have focused on finding ways to predict the scattering from discontinuities. The experimental studies have concentrated on developing measurement techniques for determining the scattering parameters of these discontinuities.
Cross-Array Antenna With Switched Steering
Selected phase shifting of feeds to antenna elements aims antenna beam. Antenna for Space Shuttle controlled in two dimensions by double-pole, double-throw switches antenna feeds. Switches control phasing of antenna elements by transposing transmission-line delay elements between feeds to pairs of elements located on opposite sides of antenna. Same principles can be applied to antennas with additional elements along each axis.
Optically controlled phased array antenna concepts using GaAs monolithic microwave integrated circuits
The desire for rapid beam reconfigurability and steering has led to the exploration of new techniques. Optical techniques have been suggested as potential candidates for implementing these needs. Candidates generally fall into one of two areas: those using fiber optic Beam Forming Networks (BFNs) and those using optically processed BFNs. Both techniques utilize GaAs Monolithic Microwave Integrated Circuits (MMICs) in the BFN, but the role of the MMIC for providing phase and amplitude variations is largely eliminated by some new optical processing techniques. This paper discusses these two types of optical BFN designs and provides conceptual designs of both systems.