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Stacking layers of microstrip patches is a technique often used to improve the bandwidth of a patch antenna, but rarely used to increase its gain. The work presented here scales the three-layer S-band work done in to Ka-band.
This paper discusses a novel method for detecting faults in antenna arrays. The method, termed Impulse Testing, was developed for corporate-fed patch arrays where the element is fed by a probe and is shorted at its center. Impulse Testing was devised to supplement conventional microwave measurements in order to quickly verify antenna integrity. The technique relies on exciting each antenna element in turn with a fast pulse (or impulse) that propagates through the feed network to the output port of the antenna. The resulting impulse response is characteristic of the path through the feed network. Using an oscilloscope, a simple amplitude measurement can be made to detect faults. A circuit model of the antenna elements and feed network was constructed to assess various fault scenarios and determine fault-detection thresholds. The experimental setup and impulse measurements for two patch array antennas are presented. Advantages and limitations of the technique are discussed along with applications to other antenna array topologies
The author has identified the following significant results. Through combined use of imagery from ERTS-1 and NOAA-2 satellites was found that when the sun elevation exceeds 55 degrees, the ERTS-1 imagery is subject to considerable contamination by sunlight even though the actual specular point is nearly 300 nautical miles from nadir. Based on sea surface wave slope information, a wind speed of 10 knots will theoretically provide approximately 0.5 percent incident solar reflectance under observed ERTS multispectral scanner detectors. This reflectance nearly doubles under the influence of a 20 knot wind. The most pronounced effect occurs in areas of calm water where anomalous dark patches are observed. Calm water at distances from the specular point found in ERTS scenes will reflect no solar energy to the multispectral scanner, making these regions stand out as dark areas in all bands in an ocean scene otherwise comprosed by a general diffuse sunlight from rougher ocean surfaces. Anomalous dark patches in the outer parts of the glitter zones may explain the unusual appearance of some scenes.
The Automatic Patching Verification program (APV) is described which provides the hybrid computer programmer with a convenient method of performing a static check of the analog portion of his study. The static check insures that the program is patched as specified, and that the computing components being used are operating correctly. The APV language the programmer uses to specify his conditions and interconnections is similar to the FORTRAN language in syntax. The APV control program reads APV source program statements from an assigned input device. Each source program statement is processed immediately after it is read. A statement may select an analog console, set an analog mode, set a potentiometer or DAC, or read from the analog console and perform a test. Statements are read and processed sequentially. If an error condition is detected, an output occurs on an assigned output device. When an end statement is read, the test is terminated.
The CTS solar array technology experiment which consists of a solar cell test patch on the Kapton-substrate solar array and the appertaining electronics unit has been operating in geostationary orbit for nearly 1 year without any malfunction although it is expected to be strongly influenced by charging effects on the array surface. The results of a post-launch test program show that the experiment would not survive a discharge due to electrostatic charging in the test patch area. In a simulated substorm, environment discharges were obtained only below a temperature threshold of about 30 C. With solar illumination, this threshold is reduced below 0 C.
All of the data presented in this paper were obtained from the Isis 2 satellite, which was launched into a 1400-km near-circular polar orbit in April 1971. Instruments used in this study include the topside sounder for providing vertical profiles of the electron density, the Langmuir probe for measuring electron temperature and concentration, and the auroral scanning photometer for detecting optical emissions at 5577 A and 3914 A. Two distinct types of auroras (east-west-aligned oval-shaped 'patches', and isolated east-west 'detached arcs') are observed in the trough region (almost exclusively in the Northern Hemisphere) equatorward of the diffuse auroral boundary. Attention is given to comparison of patches and detached arcs, relation to magnetic indices, and relation to detached plasma and ELF hiss.
The Rai (1984,85) patch-boundary scheme for the Euler equations is described. The integration methods used to update the interior grid points are are discussed. Stability of patch-boundary schemes and the use of these schemes in Navier-Stokes calculations are mentioned. Results for inviscid, supersonic flow over a cylinder, blast wave diffraction by ramp, and the motion of a vortex in a freestream are presented. These test cases demonstrate the quality of solutions possible with the scheme.
The method of 'zonal approach' (in which the flow field is partitioned into regions with independent grids) for computation of flow over complex geometries, such as aircraft configuration, requires application of a grid-interfacing procedure. A three-dimensional conservative, boundary scheme for patched grids, applicable in generalized coordinates for arbitrary point distributions on a planar zonal surface is presented. The computation technique is derived within the framework of the Osher (1983) upwind scheme, using Euler equations. The three-dimensional interfacing method is applied to the computation of flow about a wing-canard combination using a two-zone, patched grid.
The patched mesh CSCM flow solver is used with a fast adaptive grid technique to compute complex two dimensional and axisymmetric, inviscid and viscous flows accurately and efficiently. The patched grid technique allows the user to generate the initial grid around complex regions with minimal effort. The adaptive grid strategy permits the grid points to adjust to the solution in accordance with the flow structure and user specified grid constraints and thus improve the accuracy of the solution. Solutions to challenging flow problems are obtained with adapted grids and the numerical examples and the results presented here show clearly the effectiveness of the adaptive grid solution strategy to obtain highly accurate numerical solutions with minimal human effort and computational resources.
The combined use of an implicit, upwind finite-volume scheme with an 'equivalent' gamma formulation (for real gas effects) and with a three-dimensional conservative patched grid formulation is discussed. Results are presented over a wide Mach number range on both single and patched grids.
A patched-grid algorithm for the analysis of complex configurations with an implicit, upwind-biased Navier-Stokes solver is presented. Results from both a spatial-flux and a time-flux conservation approach to patching across zonal boundaries are presented. A generalized coordinate transformation with a biquadratic geometric element is used at the zonal interface in order to treat highly stretched viscous grids and arbitrarily-shaped zonal boundaries. Applications are made to the F-18 forebody-strake configuration at subsonic, high-alpha conditions. Computed surface flow patterns compare well with ground-based and flight-test results; the large effect of Reynolds number on the forebody flowfield is shown.
The numerical technique developed by Eiseman (1985) to generate surface grids with lines clustered in areas of greater curvature is described and demonstrated. This approach combines the direct active use of surface curvature with a mean-value relaxation scheme and multigrid methods; it permits an arbitrary number of patches to be organized in a single integer array based on a patch number, an edge number, and a boundary-condition index. Grids for typical CFD applications are presented and briefly characterized.
Experimental results on the characteristics of two-layer electromagnetically coupled rectangular patch antennas are presented. In addition to the relatively large bandwidth region that occurs when the separation between the two layers is less than 0.15 wavelength, a high-gain region is found when the separation exceeds 0.3 wavelength. The relative sizes of the parasitic and fed patches are found to have significant effects on the resonant input resistance and bandwidth.
A patched-grid algorithm for the analysis of complex configurations with an implicit, upwind-biased Navier-Stokes solver is presented. Through the use of a generalized coordinate transformation at the zonal interface between two or more blocks, the algorithm can be applied to highly stretched viscous grids and to arbitrarily-shaped patch boundaries. Applications are made to the SR71 reconnaissance aircraft in a high-altitude environment at a supersonic speed and to the F/A-18 forebody-strake configuration at subsonic, high-alpha conditions, in support of the NASA High-Alpha Research Program.
A patched-grid algorithm for the analysis of complex configurations with an implicit, upwind-biased Navier-Stokes solver is presented. Results from both a spatial-flux and a time-flux conservation approach to patching across zonal boundaries are presented. A generalized coordinate transformation with a biquadratic geometric element is used at the zonal interface in order to treat highly stretched viscous grids and arbitrarily shaped zonal boundaries. Applications are made to the F/A-18 forebody-Ieading-edge extension configuration at subsonic, high-alpha conditions. Computed surface flow patterns compare well with ground-based and flight-test results; the large effect of Reynolds number on the forebody flowfield is shown.
Patched grid calculations within the framework of an implicit, flux vector split upwind/relaxation algorithm for the Euler equations are presented. Aspects of computing on patched grids are discussed including the effect of a metric-discontinuous interface on the convergence rate of the algorithm, and the effect of curvature along an interface. Applications to a converging-diverging nozzle including effects of choking and bypass slots in two dimensions are presented.
A circular patch antenna fed by an aperture-coupled microstrip line has been demonstrated at 29.3 GHz. The patch was enclosed by a cavity to reduce surface-wave interactions in an array environment and to improve heat dissipation when using active devices. The antenna exhibited a 2:1 input VSWR (voltage standing wave ratio) over a bandwidth of 12 percent from 27.52 to 30.95 GHz. The antenna should have applications in conformal phased arrays at millimeter-wave frequencies.
Two methods are outlined for imposing interpatch curvature continuity in existing Bezier bicubic patch surfaces. Each method assumes that coordinates of the corners of the patches can not be altered but the interior Bezier control point can. Each method also preserves outer edge slope and outer corner twist derivatives. Neither method requires intersection or C0 continuity nor slope or C1 continuity at the start. A computer program for each method is given in the appendices.