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A technique for improving the accuracy of G/T measurements of highly directive antennas is introduced. The technique presents was developed to overcome uncertainties in ephemeral information, antenna positioning, system gain stability, and other random and nonrandom phenomena. The particular application discussed uses Casseiopeia-A as a noise source but the technique can be adapted for use with other extraterrestrial noise sources.
For approximately 10 years the National Bureau of Standards has used the Extrapolation Technique (A. C. Newell, et al., IEEE Trans. Ant. & Prop., AP-21, 418-431, 1973) for accurately calibrating transfer standard antennas (on-axis gain and polarization). The method utilizes a generalized three-antenns approach which does not require quantitative a priori knowledge of the antennas. Its main advantages are its accuracy and generality. This is essentially no upper frequency limit and it can be applied, in principle, to any type of antenna, although some directivity is desirable to reduce multipath interence.
For approximately 10 years the National Bureau of Standards has used the Extrapolation Technique (A. C. Newell, et al., IEEE Trans. Ant. & Prop., AP-21, 418-431, 1973) for accurately calibrating transfer standard antennas (on-axis gain and polarization). The method utilizes a generalized three-antenns approach which does not require quantitative a priori knowledge of the antennas. Its main advantages are its accuracy and generality. This is essentially no upper frequency limit and it can be applied, in principle, to any type of antenna, although some directivity is desirable to reduce multipath interence.
The ability to gather real-time data from a remote site is of significant value in the far-field test of large scale non-reciprocal antenna arrays. With the advent of microprocessors, digitally controlled test equipment, and high speed data links, what was once impossible has not only become feasible but also economically realizable. This paper discusses the design of a remote data-gathering capability currently on-line at the Westinghouse Ridge Road Antenna Range. The system described is a computer-controlled phase and amplitude measuring technique remoted over a 1/3 mile range with a 56K baud fiber-optics data link. Considerations of system configuration, timing, protocol, error-detection and self-diagnostics are discussed.
The ability to gather real-time data from a remote site is of significant value in the far-field test of large scale non-reciprocal antenna arrays. With the advent of microprocessors, digitally controlled test equipment, and high speed data links, what was once impossible has not only become feasible but also economically realizable. This paper discusses the design of a remote data-gathering capability currently on-line at the Westinghouse Ridge Road Antenna Range. The system described is a computer-controlled phase and amplitude measuring technique remoted over a 1/3 mile range with a 56K baud fiber-optics data link. Considerations of system configuration, timing, protocol, error-detection and self-diagnostics are discussed.
Millimeter wave antenna measurements are hampered by a lack of cost effective automated test equipment and the necessity of using unwieldy waveguide set-ups. This paper describes some practical considerations in using readily available test equipment to perform accurate, repeatable antenna measurements. Experimental results of gain, polarization and sidelobe level measurements will be discussed and compared with calculated results.
Millimeter wave antenna measurements are hampered by a lack of cost effective automated test equipment and the necessity of using unwieldy waveguide set-ups. This paper describes some practical considerations in using readily available test equipment to perform accurate, repeatable antenna measurements. Experimental results of gain, polarization and sidelobe level measurements will be discussed and compared with calculated results.
Paper not available for presentation.
Paper not available for presentation.
Rapid advances in digital and micro-computer technology have revolutionized automated control of most measurement processes and the techniques for analysis, storage and presentation of the resulting data. Present-day computer capabilities offer many “user-friendly” options for antenna instrumentation, some of which have yet to be exploited to their full potential. These range from vendor-integrated turnkey systems to innovative designs employing a multitude of subsystem components in custom-interfaced configurations. This paper reviews system and component choices keeping in mind their relative merits and trade-offs. Key design considerations are outlined with particular emphasis on: a) Integration and interfacing of different instrumentation, hardware and software subsystems. b) Upgrading and/or designing of completely new facilities. Various other problems, such as vendor package compatability, and those associated with the analysis and application of measured antenna data are discussed. In addition, suggestions are offered to promote the establishment of a mechanism to facilitate the interchange of data between different antenna measurement laboratories and analysis centres.
Rapid advances in digital and micro-computer technology have revolutionized automated control of most measurement processes and the techniques for analysis, storage and presentation of the resulting data. Present-day computer capabilities offer many “user-friendly” options for antenna instrumentation, some of which have yet to be exploited to their full potential. These range from vendor-integrated turnkey systems to innovative designs employing a multitude of subsystem components in custom-interfaced configurations. This paper reviews system and component choices keeping in mind their relative merits and trade-offs. Key design considerations are outlined with particular emphasis on: a) Integration and interfacing of different instrumentation, hardware and software subsystems. b) Upgrading and/or designing of completely new facilities. Various other problems, such as vendor package compatability, and those associated with the analysis and application of measured antenna data are discussed. In addition, suggestions are offered to promote the establishment of a mechanism to facilitate the interchange of data between different antenna measurement laboratories and analysis centres.
This paper presents a three-antenna plane-wave scattering-matrix (PWSM) formulation and a formal solution. An example will be demonstrated in which two of the three antennas are electromagnetically identical (the transmitter and the receiver) and the third (the scatterer) has arbitrary electromagnetic properties. A reduced reflection integral-matrix will be discussed which describes the transmit, scatter, receive (TSR) interaction. An antenna scatterer spectral tensor Greens function is identified. In this formulation the transmit spectrum will be scattered by the third arbitrary antenna (target) and this scattered spectrum may be considered to have originated from a transmitting antenna. Near-field antenna measurement techniques are applicable with determine the electric (scattered) field spectral density function.1, 2 If a second deconvolution is applied, a transmit probe corrected spectral density function or scattering tensor can be determined in principle. In either case, a near- or far-electric field can be calculated and a radar cross section determined.
This paper presents a three-antenna plane-wave scattering-matrix (PWSM) formulation and a formal solution. An example will be demonstrated in which two of the three antennas are electromagnetically identical (the transmitter and the receiver) and the third (the scatterer) has arbitrary electromagnetic properties. A reduced reflection integral-matrix will be discussed which describes the transmit, scatter, receive (TSR) interaction. An antenna scatterer spectral tensor Greens function is identified. In this formulation the transmit spectrum will be scattered by the third arbitrary antenna (target) and this scattered spectrum may be considered to have originated from a transmitting antenna. Near-field antenna measurement techniques are applicable with determine the electric (scattered) field spectral density function.1, 2 If a second deconvolution is applied, a transmit probe corrected spectral density function or scattering tensor can be determined in principle. In either case, a near- or far-electric field can be calculated and a radar cross section determined.
This paper describes a digitally controlled receiver-recorder capable of time division multiplexing in the frequency domain at a 400 KHz rate and in the amplitude domain at a 20 MHz rate. Good sensitivity and interference rejection are other features of this receiver which operates over the 2-18 GHz band. It is utilized to obtain a measure of antennas performance as impacted by air frames upon which the antenna(s) are mounted.
This paper describes a digitally controlled receiver-recorder capable of time division multiplexing in the frequency domain at a 400 KHz rate and in the amplitude domain at a 20 MHz rate. Good sensitivity and interference rejection are other features of this receiver which operates over the 2-18 GHz band. It is utilized to obtain a measure of antennas performance as impacted by air frames upon which the antenna(s) are mounted.
One of the variables to be quantified when making antenna measurements is position. Without accurate and timely position information, the spatially dependent data cannot be correctly interpreted. Scientific-Atlanta’s 1885 Positioner Indicator and 1886 Position Data Processor offer several improvements in providing position information which can enhance an antenna measurement system. New position indicating techniques have been implemented to allow a higher degree of accuracy and speed than previously attainable. These have been combined with advanced features for automatic system flexibility to create a high performance instrument for many applications. This paper describes the capabilities of these two instruments and how they can be used to improve system performance.
One of the variables to be quantified when making antenna measurements is position. Without accurate and timely position information, the spatially dependent data cannot be correctly interpreted. Scientific-Atlanta’s 1885 Positioner Indicator and 1886 Position Data Processor offer several improvements in providing position information which can enhance an antenna measurement system. New position indicating techniques have been implemented to allow a higher degree of accuracy and speed than previously attainable. These have been combined with advanced features for automatic system flexibility to create a high performance instrument for many applications. This paper describes the capabilities of these two instruments and how they can be used to improve system performance.
The complete sequence of RF tests required to evaluate the electrical performance of a broad band UHF helix antenna to be used in the zero gravity environment of space is described. The development of an adequate structure which would support the antenna and yet cause no pattern perturbation is mentioned. The test range configuration used, with the UHF antenna inside and anechoic chamber and the source antenna illuminating it through a polyfoam window in one side, is discussed. The problems encountered in taking radiation pattern plots and in making gain measurements using a gain standard near the low frequency limit, 250 MHz, of the antenna test range and the methods utilized to minimize their effect are given in some detail.
The complete sequence of RF tests required to evaluate the electrical performance of a broad band UHF helix antenna to be used in the zero gravity environment of space is described. The development of an adequate structure which would support the antenna and yet cause no pattern perturbation is mentioned. The test range configuration used, with the UHF antenna inside and anechoic chamber and the source antenna illuminating it through a polyfoam window in one side, is discussed. The problems encountered in taking radiation pattern plots and in making gain measurements using a gain standard near the low frequency limit, 250 MHz, of the antenna test range and the methods utilized to minimize their effect are given in some detail.
RCA-Astro Electronics in Princeton, N.J. designs, develops and tests multiple-beam offset reflector antenna systems in the C and Ku frequency bands for satellite communications. Antenna measurements are performed at the antenna subsystem and the system level and on the complete spacecraft to demonstrate that alignment and performance meet their specification. This paper discussed the antenna range designs and test techniques involved in data acquisitions for contour patterns, cross-polarization isolation and antenna gain characterization. A description of the software required to obtain, analyze and present the data will be included in addition to typical test results.