A Large-Antenna Microwave Radiometer-Scatterometer Concept for Ocean and Land Sensing
Microwave radiometry and scatterometry are established techniques for surface remote sensing applications.
radiometer scatterometer remote sensing antenna oc↗
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DSN 100-meter X and S band microwave antenna design and performance
The RF performance is studied for large reflector antenna systems (100 meters) when using the high efficiency dual shaped reflector approach. An altered phase was considered so that the scattered field from a shaped surface could be used in the JPL efficiency program. A new dual band (X-S) microwave feed horn was used in the shaping calculations. A great many shaping calculations were made for various horn sizes and locations and final RF efficiencies are reported. A conclusion is reached that when using the new dual band horn, shaping should probably be performed using the pattern of the lower frequency
Williams, W. F.↗
Multiple-reflection conical microwave antenna
Conical-Gregorian antenna concept, using conical reflector, promises excellent rf performance and offers potential advantages in areas of mechanical and structural design, surface measurement, and in furlability. Multiple reflection scheme between one or more subreflectors and main reflector is utilized. Subreflector can be reduced to as little as 0.1 the diameter of main reflector.
Oliver, R. E.↗
Dual-frequency microwave antenna
Single antenna using two feed horns (one for receiving and radiation X-band signals, and one for S-band signals), in conjunction with ellipsoid reflector and dichronic plate, can accommodate two different frequencies simultaneously.
Bathker, D. A.↗
Compact Dual-Mode Microwave Antenna
Compact dual-mode antenna, 3.66 cm wide by 1.83 cm thick is used both for heating and thermographic detection of tumors in cancer research. Temperature sensor operates independently or simultaneously with heater. Antenna includes 1.6-GHz transmitter and 4.76-GHz receiver. Strip heater between antennas controls temperature of device. Maximum power output is 25 W.
Carr, K. L.↗
Antenna Microwave Subsystem Controller
The development of a new microwave subsystem controller is discussed, and results of installing the equipment at the DSS 13 R&D station are reported. This controller is serving as the prototype for a new generation of microwave controllers for the DSN.
Freiley, A.↗
Microwave Antenna With Reduced Noise Leakage
Gain or gain-to-temperature ratio of dual-shaped subreflector receiving antenna increased when illumination is tapered near aperture edge. Taper imposed in antenna feed reduces spillover in transmitting mode and reduces noise pickup in receiving mode.
Cha, A. G.↗
DSN microwave antenna holography. Part 2: Data processing and display of high-resolution effective maps
The results of a recently completed computer graphic package for the process and display of holographically recorded data into effective aperture maps are presented. The term effective maps (labelled provisional on the holograms) signifies that the maps include contributions of surface mechanical errors as well as other electromagnetic factors (phase error due to feed/subreflector misalignment, linear phase error contribution due to pointing errors, subreflector flange diffraction effects, and strut diffraction shadows). While these maps do not show the true mechanical surface errors, they nevertheless show the equivalent errors, which are effective in determining overall antenna performance. Final steps to remove electromagnetic pointing and misalignment factors are now in progress. The processing and display of high-resolution effective maps of a 64m antenna (DSS 63) are presented.
Rochblatt, D. J.↗
Deviations Of Microwave Antennas From Homology
Surface distortions quantified over range of tilt angles. Formula advanced to quantify deviation of paraboloidal antenna reflector from intended homologous shape, over range of tilt ranges.
Kiedron, Krystyna↗
Command Preprocessor for Radiotelescopes and Microwave Antennas
The LQG controllers, designed for the NASA Deep Space Network antennas have small tracking errors and are resistant to wind disturbances. However, during antenna slewing, they induce limit cycling caused by the violation of the antenna rate and acceleration limits. This problem can be avoided by introduction of a command that does not exceed the limits. The command preprocessor presented in this paper generates a command that is equal to the original command if the latter does not exceed the limits, and varies with the maximal (or minimal) allowable rate and acceleration if the limits are met or exceeded. It is comparatively simple since it requires only knowledge of the command at the current and the previous time instants, while other known preprocessors require knowledge of the terminal state and the acquisition time. Thus, the presented preprocessor is more suitable for implementation. In this article analysis of the preprocessor is presented. Also the performances of the preprocessor itself, and of the antenna with the preprocessor is illustrated with typical antenna commands.
Gawronski, Wodek↗
Command Preprocessor for Radiotelescopes and Microwave Antennas
The LQG controllers, designed for the NASA Deep Space Network antennas have small tracking errors and are resistant to wind disturbances.
Antennas↗
Reflection-Zone-Plate Antenna
Microwave antenna, based on reflection holography, designed and tested. Modified to produce arbitrary beam patterns by controlling relief pattern. Antenna planar or contoured to supporting structure. Low off-axis radar cross section at frequencies removed from operational frequency. Interference pattern produced by spherical wave intersecting plane wave consists of concentric circles similar to Newton's rings. Pattern identical to Fresnel zone plate, which has lens properties. Plane wave incident on hologram, or zone plate, focused to point.
Franke, John M.↗
Application of spherical near-field measurements to microwave holographic diagnosis of antennas
Microwave diagnosis of antennas is considered as a viable tool for the determination of reflector surface distortions and location of defective radiating elements of array antennas. A hybrid technique based on the combination of the spherical near-field measurements and holographic metrology reconstruction is presented. The measured spherical near-field data are first used to construct the far-field amplitude and phase patterns of the antenna on specified regularized u-nu coordinates. These data are then utilized in the surface profile reconstruction of the holographic technique using a fast-Fourier-transform (FFT)/iterative approach. Results of an experiment using a 156-cm reflector antenna measured at 11.3 GHz are presented for both the original antenna and the antenna with four attached bumps. Several contour and gray-scaled plots are presented for the reconstructed surface profiles of the measured antennas. The recovery effectiveness of the attached bumps has been demonstrated. The hybrid procedure presented is used to assess the achieved accuracy of the holographic reconstruction technique because of its ability to determine very accurate far-field amplitude and phase data from the spherical near-field measurements.
Rahmat-Samii, Yahya↗
Omnidirectional microwave spacecraft antenna Patent
Microwave ominidirectional antenna for use on spacecraft
Croswell, W. F.↗
Antennas for spaceborne microwave radiometers
Principles and applications of microwave radiometry to remote sensing of the earth from satellites are reviewed. Examples of some spaceborne radiometer systems currently in use or under consideration are given. The requirements on performance characteristics of microwave antennas for such spaceborne earth sensing radiometers, such as coverage, scanning, spatial resolution, insertion loss, beam efficiency, polarization purity, etc., and their effects on the overall radiometer system performance are discussed.
Shiue, J. C.-C.↗
The spacecraft antennas
The spacecraft employs two microwave antennas for communications and a single VHF antenna for telemetry, beacon, and command functions. One microwave antenna centered at 6 gc is used to receive broadband signals from a ground transmitter while the other microwave antenna centered at 4 gc is used to transmit signals to a ground receiver. Each microwave antenna is composed of a large number of circularly polarized radiating elements equally spaced around the equator of the spacecraft and connected to the electronic receiver and transmitter by a complex precision feed system. The VHF antenna is a small multi-element helix mounted at the pole of the spacecraft and radiates a linearly polarized signal. All antennas provide nearly isotropic antenna patterns with the axis of symmetry corresponding to the spin axis of the spacecraft. The antenna systems were constructed of light, but rugged, materials and passed extensive electrical, mechanical, and thermal tests.
ANTENNA↗
Microwave power receiving antenna Patent
Microwave power receiving antenna solving heat dissipation problems by construction of elements as heat pipe devices
Dailey, C. C.↗
Advanced microwave radiometer antenna system study
The practicability of a multi-frequency antenna for spaceborne microwave radiometers was considered in detail. The program consisted of a comparative study of various antenna systems, both mechanically and electronically scanned, in relation to specified design goals and desired system performance. The study involved several distinct tasks: definition of candidate antennas that are lightweight and that, at the specified frequencies of 5, 10, 18, 22, and 36 GHz, can provide conical scanning, dual linear polarization, and simultaneous multiple frequency operation; examination of various feed systems and phase-shifting techniques; detailed analysis of several key performance parameters such as beam efficiency, sidelobe level, and antenna beam footprint size; and conception of an antenna/feed system that could meet the design goals. Candidate antennas examined include phased arrays, lenses, and optical reflector systems. Mechanical, electrical, and performance characteristics of the various systems were tabulated for ease of comparison.
Kummer, W. H.↗