AMTA Paper Archive


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AMTA Paper Archive

Modern antenna test facility for new generation space-borne antennas
R.C. Whitehouse (Spar Aerospace Ltd.),L.A. Wegrowicz (Spar Aerospace Ltd.), T. Pavlasek (McGill University), November 1986

Spar Aerospace, along with other aerospace companies, have experienced an evolution in the development of spacecraft antennas over the past 20 years. Spacecraft antennas originated as either simple antennas providing figure of revolution patterns for spin stabilized communication satellites or simple monopoles for telemetry and command purposes. Communication satellite antennas later evolved to shape beam reflector type configurations. Spaceborne antennas are now moving to even larger reflector antennas and to planar arrays for radar applications. This evolution in spaceborne antennas has been followed by a parallel evolution in antenna test facilities and facilities requirements.

Prime focus feeds for the compact range
J.R. Jones (Scientific-Atlanta), November 1986

Prime focus fed paraboloidal reflector compact ranges are used to provide plane wave illumination indoors at small range lengths for antenna and radar cross-section measurements. The "quiet zone", which is the region of space within which a uniform plane wave is created, has previously been limited to a small fraction of the reflector size. A typical quiet zone might be six feet by four feet for a ten foot radius reflector.

Large compact range quiet zone characteristics
J.D. Huff (Scientific-Atlanta, Inc.), November 1986

Measurements of the Electromagnetic Field in the quiet zone of Scientific-Atlanta's Model 5753 Compact Range are presented. The Model 5753 is believed to be the largest high frequency compact range yet built and measurements demonstrate a quiet zone exceeding 8 ft. high by 12 ft. wide. Both field probe measurements and pattern comparison measurements are presented in the operating frequency range of 1-94 GHz.

Applications of ISAR imaging techniques to near-field RCS measurements
E.V. Sager (System Planning Corporation),J.C. Davis (System Planning Corporation), R.J. Sullivan (System Planning Corporation), November 1986

This paper discusses some of the applications of high-resolution coherent radar image processing techniques in unimproved indoor facilities. The techniques are particularly useful in situations where traditional indoor range chambers are unavailable or impractical. Experiments in an 18-foot-high warehouse building have shown that useful measurements can be made at close quarters, in a high-clutter environment.

Problems in antenna range comparison
J. Lemanczyk (Technical University of Denmark),F.H. Larsen (Technical University of Denmark), J.A. Hammer (ESTEC), November 1986

With the development of precise antenna measurement systems and the increasing demands on antenna performance, attention is more and more turning towards the requirements of antenna measurement systems and their verification. One way a verification can take place is by measuring on several systems one common antenna. There are a number of advantages and disadvantages associated with such an exercise, however several purposes are served, not least amongst which is the confidence gained on the part of a customer that the range in question has demonstrated certain capabilities.

Planar and cylindrical near field facility - a S-A 2020 upgrade
B. Cyzs (RAFAEL ),A. Geva (RAFAEL ), A. Paz (RAFAEL ), M. Israel (RAFAEL ), Y. Botvin (RAFAEL ), November 1986

A planar and cylindrical near field facility is described. The facility was designed, constructed and integrated at RAFAEL as an extension to its veteran S-A 2020 Antenna Analyzer. The system utilizes open loop stepper motors for linear motion. Operation modes include cartesian, plane-polar and cylindrical measurements. All measurement control and data acquisition functions are performed by the 2020 computer. Conversion routines are being run on a host CDC CYBER mainframe computer and include a new algorithm for polar probe correction.

An Immediate and near field volume scanning X and K band facility
P. Ilott (McGill University),L.A. Wegrowicz (Spar Aerospace Ltd.), P. Markland (McGill University), T. Pavlasek (McGill University), November 1986

Fundamental research in the behaviour of the electromagnetic field in the immediate vicinity of radiators, scatterers or diffracting objects, indicates the need for equipment capable of scanning the three dimensional volume surrounding such objects. Such equipment requires the ability to determine the amplitude and phase of the vectorial components of the fields in a variety of ways, such as on a three dimensional grid of uniformly or otherwise spaced points, on regular (such as spherical, paraboloidal) or on arbitrarily defined surfaces or along various loci.

Improving the accuracy of the planar near-field far-field transformation by a proper choice of integration algorithm and grid
M.S.A. Sanad (University of Manitoba),L. Shafai (University of Manitoba), November 1986

The planar scanning system is commonly used in the near field testing of high gain antennas, where the rectangular measurement grids are used. The polar grids are also used, which are more convenient when the antenna aperture is circular. In the planar scanners the measurements are carried out in the x-y plane in increments of both x and y. The result of the measurement is an mxn matrix of the near field data consisting of m cuts with n data points per each cut. The far field patterns may then be calculated, using the near field data, by the aperture field integration or the modal expansion methods [1]. In this paper the aperture field integration method is studied, where the far field components can be calculated from [1] - [2].

Multiple reflection effects on a near-field range
M.H. Francis (National Bureau of Standards),A. Newell (National Bureau of Standards), November 1986

The NBS has developed a test for estimating the effects of multiple reflections between the probe and antenna on the far field using a near-field measurements. The essence of this test is to take near-field data at more than one separation distance. For each separation distance the far field is obtained using a Fourier transform. The different far fields are then averaged in a complex manner. The difference between the average far field and each of the other far fields is due to multiple reflection effects.

Near-feld testing of the 30 GHz TRW proof-of-concept multibeam antenna
R.R. Kunath (National Aeronautics and Space Administration),R.J. Zakrajsek (National Aeronautics and Space Administration), November 1986

Near-field testing was conducted on the 30 GHz TRW proof-of-concept (POC) Multibeam Antenna (MBA). The TRW POC MBA is a dual offset cassegrain reflector system using a 2.7 m main reflector. This configuration was selected to assess the ability to create both multiple fixed and scanned spot beams. The POC configuration investigated frequency reuse via spatial separation of beams, polarization selectivity and time division multiple access scanning at 30 GHz.

Interpretation of the focus curve of paraboloidal reflectors
T.H. Legg (National Research Council, Ottawa), November 1986

Some large paraboloidal reflectors, such as radio telescopes, have a means of remotely adjusting the axial position of their feed. For these reflectors it takes little effort to measure a "focus curve", i.e. the intensity of radiation received as a function of the axial position of the feed. The purpose of this note is to point out how this curve can be interpreted to give information about the reflector surface.

Characterization of antennas for RCS measurements
S. Kashyap (National Research Council, Ottawa),S. Mishra (National Research Council, Canada), November 1986

This paper reviews procedures and techniques employed for calibrating antennas used in electromagnetic compatibility (EMC) measurements. Details of our measurement procedure and results using the TEM cell and the three antenna methods are described.

Measured blockage of a parabolic antenna by a tall vertical obstruction
D. Sirmans (National Severe Storms Laboratory), November 1986

It is sometimes necessary to tolerate a narrow vertical obstacle in proximity to an antenna system. This study quantifies the effects on the antenna horizontal pattern of an obstruction with vertical dimension large compared to the antenna and horizontal dimension small compared to the antenna. Both dimensions are large compared to wavelength.

Near-field measurement of radome performance
E.B. Joy (Georgia Institute of Technology),C. Hill (Georgia Institute of Technology), R.E. Wilson (Georgia Institute of Technology), S.J. Edwards (Georgia Institute of Technology), W.D. Caraway (Georgia Institute of Technology), November 1986

This paper reports on the measurements portion of an ongoing research program at the Georgia Institute of Technology into the design, analysis and measurement technologies of radomes. Specifically this paper reports on a technique for the near-field measurement of radome performance. The motivation for the development of the near-field measurement technique for radomes is to identify the types of interactions which take place between the radome and the transmitted electromagnetic field. It is postulated that such phenomena as coupling to the radome wall, tip scattering, internal reflections and bulkhead reflection would be easier to identify through near-field measurement than far-field measurement. * This work was supported by the Joint Services Electronics Program and Northrop Corporation

Application of digital filtering (FFT) techniques to the measurement of absorber and anechoic chamber properties
J.C. Hungerford (Emerson & Cuming, Inc.),C.M. Robinson (Emerson & Cuming, Inc.), November 1986

Three measurements commonly used in the absorber industry include absorber testing in NRL arches, testing absorber in waveguides, and testing performance of anechoic chambers. These measurements are closely related. All are looking for the size of one E field vector in the presence of several other E fields of variable amplitudes and phases. The information is extracted from the behavior of the sum as a function of some physical position change or frequency change. Computer controlled, synthesized sources and receivers have had two effects on the way these measurements may be taken and interpreted. First, the data are now available as a series of numbers in a computer instead of a series of lines on a piece of paper. Precise and elegant processing is available to extract the information from the data. Secondly, since frequency changes are made rapidly with this type of instrumentation, and precise position changes are made slowly, the data may be taken for many frequencies at each physical position, this makes it possible to extract additional information from the observed data changes as a joint function of frequency and position. These changes are spread throughout the block of data for signal amplitude vs position and frequency.

Spectral evaluation of reflector surfaces used for compact ranges
E.B. Joy (Georgia Institute of Technology),R.E. Wilson (Georgia Institute of Technology), November 1986

This paper presents the results of a study conducted to determine the effects of reflector surface errors on compact range performance. The study addressed only the reflector surface accuracy and not edge scattering, reflector illumination or reflector size. The study showed that low spatial frequency sinusoidal surface errors are significant contributors to amplitude ripple in the quiet zone field. Simple equations are presented for estimation of quiet zone amplitude ripple due to reflector surface errors. The study also presents measured surface error for two manufactures of reflector panels. The spectral (plane wave) components of the reflected field are displayed for a compact range reflector composed of a collection of these panels. *This work supported by the U. S. Army Electronic Proving Ground, Ft. Huachuca, AZ and the Joint Services Electronics program

A Concave edged reflector with blended rolled surface terminations for compact range applications
C.W.I. Pistorius (The Ohio State University ElectroScience Laboratory),W.D. Burnside (The Ohio State University ElectroScience Laboratory), November 1986

A compact range is a facility used for the measurement of antenna and target scattering parameters. It offers many advantages over other types of ranges, and consequently a lot of effort is being directed towards the improvement of compact range performance. This discussion focusses on the reduction of diffracted fields from the termination of the parabolic main reflector. *This work was supported in part by the National Aeronautics and Space Administration, Langley Research Center, Hampton, Virginia under Grant NSG 1613 with the Ohio State University Research Foundation.

Holographic antenna measurements using a single receiver
T.H. Legg (National Research Council, Ottawa), November 1986

Holography measurements (see for example Bennet et al., 1976 and Scott and Ryle, 1977) have recently been made in which it was possible to use a single receiver and no correlator. The object was to measure the deformation with changing elevation angle of the 46m radio telescope at the Algonquin Radio Observatory, Lake Traverse, Ontario. To allow measurements over a wide range of elevation angle, the emission from natural water-line (22.235 GHz) masers was chosen as a source of signal.

Measurement of element pattern and its usage in the development of multi-beam arrays
P. Kirshner (ELTA Electronic Industries),I. Oz (ELTA Electronic Industries), November 1986

Electronic scanning phased arrays are being used more and more in radar, EW and communication systems. The development of such an array can be divided into two separate parts: development of the radiating elements and development of the beam forming network. The development of these two parts is often done in parallel and the radiating elements should always be developed taking into consideration the whole array and not only single elements.

Troubleshooting test facilities with a high resolution instrumentation radar
T.J. Lyon (The Howland Company, Inc.),A.R. Howland (The Howland Company, Inc.), November 1986

This paper presents data from facility evaluation tasks on current projects. The data were obtained on outdoor free-space pattern test facilities, and in anechoic chamber RCS test facilities.







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