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When mounted on spacecraft , pattern of some antennas are perturbed by the presence of satellite body. The prediction of antenna performances including satellite structure effect is generally done at early stage of antenna design but is limited in terms of model complexity. The test on full spacecraft & in far field condition is then necessary. This solution is very expensive as it means for test at satellite level to use Compact antenna Test Range in order to satisfy cleanliness aspects. For the Meteosat Second Generation (MSG) program test on the toroidal antennas need to be performed on different model including a flight model. A good compromise was to use the external omnidirectional antenna range and a part of satellite structure representing the major contributor for the antenna pattern as identified via numerical analysis. The external range offer possibilities that cannot be reached in Compact range, e.g. low cost, full sphere pattern, low frequency range.
Boeing is currently pursuing certification of their 9-77 indoor compact range facility as a voluntary industrial participant in the ongoing DoD/NIST RCS certification demonstration program. In support of that process, V EI has applied a novel statistical method for analysis to VHF measurements of a canonical target from the Boeing 9-77 range. The dominant error sources in the range were identified and categorized according to their dependence on frequency, aspect angle, and the target under test. Range characterization data were collected on canonical targets and then used to estimate the statistical parameters of each of the errors. Finally, these were incorporated into expressions for the combined RCS measurement uncertainty for a test body whose RCS exhibits many of the characteristics of modern, high-value targets. The results clearly demonstrate the importance of accounting for the target-dependence of the errors and the bias they introduce into the overall uncertainty.
This paper describes how ANSI standard Z-540 [l,2,3] was applied in a DoD demonstration project to organize radar cross section (RCS) range documentation for the Air Force Research Laboratory Advanced Compact Range (ACR) and Patu:xent River Atlantic Test Range (ATR) Dynamic RCS measurement facility. Both parts of this paper represent a follow-up report on the DoD demonstration program introduced at AMTA 97 [4]. In June 2000, the DoD Range Commanders Council Signature Measurement and Standards Group (RCC/SMSG) certified that these two facilities met the ANSI-Z-540 documentation standards established by the DoD demonstration project. Since AFRL plans to require mandatory ANSI-Z-540 compliance for DoD contractors performing RCS measurements with AFRL after January 1, 2004, the review process described in this paper will be the likely model for industrial compliance. After a brief review of the ANSI-Z-540 standard, Part 1 of this paper will outline the certification review process and discuss the outcomes, results, and lessons learned from the DoD demonstration program from the perspective of the AFRL range and volunteer range reviewers.
This paper describes how ANSI/NCSL standard Z- 540 [1, 2] was applied in a DoD demonstration project to organize radar cross section (RCS) range documentation for the Air Force Research Laboratory (AFRL) Advanced Compact Range (ACR) and the Naval Ai:r Warfare Center - Aircraft Division (NAWC-AD) Atlantic Test Range (ATR) Dynamic RCS measurement facility. Both parts of this paper represent a follow-up report on the DoD demonstration program introduced at AMTA 97 [3]. In June 2000, the DoD Range Commanders Council Signature Measurement and Standards Group (RCC/SMSG) certified that these two facilities met the ANSI/NCSL Z-540 documentation standards established by the DoD demonstration project. Since AFRL plans to require mandatory ANSI/NCSL Z- 540 compliance for DoD contractors performing RCS measurements with AFRL after January 1, 2004, the review process described in this paper will be the likely model for industrial compliance. Part I of this paper contained a brief summary of the ANSI/NCSL Z-540 standard, outlined the certification review process and discussed the outcomes, results, and lessons learned from the DoD demonstration program from the perspective of the AFRL range and volunteer range reviewers. Part II will discuss the review process as it applied to ATR, as well as the outcomes, results, and lessons learned.
Allgon Systems AB has put a new compact antenna test range into operation in July 2000. The investment was triggered by Allgon's planned move to a new building. An indoor facility was preferred for fast and efficient operation. The present primary application is the measurements of base station antennas. The compact range is constructed using a single reflector with serrated edges. A sophisticated feed carrousel enables automatic changing of 3 feed systems. The size of the quiet zone is 3 meters. The initial frequency range is from 800 to 6000 MHz. However, the reflector accuracy allows future extensions to 40 GHz and higher. The cha mber size is 21 x 12 x 10.5 m (L x W x H). Absorber layout comprises 24, 36 and 48 inch absorbers. An overhead crane spans the entire facility. The positioner system is configured as roll over azimuth with a lower elevation over azimuth for pick-u p and small elevation angle measurements. Different sizes of masts and roll positioners are available, depending on the AUT. Instrumentation is based on a HP 8753. Software is based on the FR-959 Plus. Antenna measurement results show the performance of the facility.
GE Aircraft Engines (GEAE) in Cincinnati, Ohio recently built a compact range facility to operate from 800 MHz to 18 GHz. The design process included visits to other :recently completed facilities so that industry best practices could be incorporated into the design of the state-of-the-art facility. The facility includes a 30 x 30-x 65-ft. chamber, corner fed blended rolled edge reflector, Chebyshev Multilevel absorbers, a 12-ft. diameter tu rntable, and rail mounted gantry crane for target mounting, Facility design, chamber, reflector, absorber, target handling and fire protection systems are discussed.
This paper presents the electromagnetic effects of low level non-random error on a compact range reflector surface. Physical optics computational analyses are presented illustrating the effect. Furthermore, actual case study results from the new GE/NT Compact Range Facility are also shown in which a non-random error of 3 mil RMS was discovered. Finally, a process is presented in which the non-random nature of the error was analyzed and removed from the surface. Before and after field probe measu rements illustrate the dramatic effect of such error.
An important source of error in a compact range antenna pattern measurement is the deviation of the quiet-zone field from the perfectly fiat amplitude and phase of a plane wave field. Although some guidelines and rules of thumb exist that relate the quiet-zone field to the error in the measured antenna patterns, the error or perturbation is dependent on the particular type of antenna that is being measured. For example, the non-ideal quiet zone field will produce very different errors for a small horn than for a large phased array. A realistic error budget or uncertainty analysis of the compact-range measurement requires knowledge of the antenna pattern uncertainty as a function of the quiet-zone field and the particular antenna of interest. A simulation method is derived using reciprocity that allows one to quantify the perturbations induced in a given antenna pattern when the quite-zone field distribution is known. This is particularly useful, since one typically has a fair estimate of the antenna pattern and has measured data of the quiet-zone field. The simulation is tested by modelling the antenna as a collection of elemental current sources and simulating the quiet-zone field as generated by elemental current sources. Using this simple simulation model, a closed-form near-field antenna pattern may be calculated for comparison with the more general computer simulation derived from reciprocity.
Many aircraft radome structures are designed to operate simultaneously over multiple RF bands and incident polarizations. Critical parameters must be measured over the electrical apertures of the radome and across each operating band. Automated measurement techniques are required to efficiently collect the large volume of test data required. A modular broadband feed assembly has been developed to allow the simultaneous collection of multi-band, multi-polarization data on a compact range without the need to mechanically change feeds. The feed assembly utilizes a sinuous antenna as the radiating element and is capable of operation from 2-18 GHz with electronically selectable polarization states. Feed design criteria as they relate to compact range antenna and radome measurements are discussed. Of primary importance are reflector illumination pattern, linear polarization cross-polarization level, and circular polarization axial ratio. Polarization switching requirements for a specific test application are defined and the physical implementation of the integrated feed assembly is described. Measured feed and quiet zone performance data is presented for this application. The polarization switching configuration can be readily modified to support other applications.
Nowadays, highly accurate antenna pattern and RCS measurements are performed in compensated compact range test facilities, which fulfil the stringent space requirements for measurements up to 500 GHz and more. As the suppression of diffracted fields from the reflectors mainly determine the quiet zone field performance, the reflector edge treatment is an important design parameter for this type of test facilities. Within the present paper a novel serration design wm be shown. The analyses as well as measurement results exhibit a clear improvement of the quiet zone field performance when compared to previous solutions. The new serration design was implemented and proved with the CCR 20/17 of Astrium GmbH at the Munich University of Applied Sciences.
Compact ranges have found wide use in the pa rametric characterization of high performance radomes such as those found on modern military aircraft. A properly designed compact range facility provides a stable, repeatable test environment suitable for the measurement of small variations in antenna boresight position (beam deflection), antenna pattern distortion, and transmission loss. Radomes have increased in complexity from small structures housing a single antenna to multi-band, multi-system structures large enough to stand inside. Similarly, compact range reflectors have increased in commercial units available today provide quiet zone extents of 12 feet or larger. This paper describes the system design and performance of a compact range test facility designed to test a C-130 Combat Talon II nose radome measuring 7 feet in length and diameter. The facility was constructed at Robins AFB, GA, and is in operation. A description of the facility and its major subsystems is given. Sizing of the chamber and layout of equipment is described. Chamber electromagnetic design considerations are discussed. Electromagnetic design was complicated by the physical size of the structure required to mount the radome, by the fact that multiple antennas and gimbals are present inside the radome during testing, and by the need to use a broad band feed to eliminate mechanical feed changes. Absorber layout and control of spurious reflections is discussed. Electromagnetic performance data is presented.
This paper describes the alignment procedure for using a spherical near-field measurement facility to determine incident fields throughout a spherical volume. This information can be used, for example, to characterize an anechoic chamber or the quiet zone of a compact range. A probe is mounted on a standard roll-over-azimuth positioner and aligned looking out of the sphere so its aperture maps out the surface of a sphere. The probe measures the amplitude and phase of the fields incident on the sphere. This method differs from the standard spherical near-field measurement where the source antenna serves as the probe and is looking into a sphere containing the test antenna.
Microwave Instrumentation Technologies (MI Technologies) in cooperation with Hollandse Signaalapparaten B.V. (Signaal) and the Royal Netherlands Navy has designed and produced a compact antenna test range to specifically address the unique testing requirements imposed in the testing of active phased array antennas. The compact range was built specifically to test Signaal's new Active Phased Array Radar (APAR) prior to introduction into various naval fleets throughout the world. This reversible Compact Antenna Test Range (CATR) allows antenna testing in both transmit and receive modes. The measurement hardware is capable of testing both CW and pulsed waveforms with high dynamic range. In addition to conventional antenna pattern measurements the system is capable of measuring EIRP, Gff and G/NF, as well as providing analysis software to provide aperture reconstruction. A special Antenna Interface Unit (AIU) was designed and built to communicate with the Beam Steering Computer which controls the thousands of T/R modules which make up the APAR antenna system. A special high power absorber fence and other safeguards were installed to handle the transmit energy capable of being delivered from the APAR antenna system.
In order to reduce the cost of building compact range reflectors, a combination of a circular rim reflector and R-card fence can be used. Circular rim reflectors are commercially available at reasonable prices. The R-card sheets are also inexpensive. Since the R-card works as a fence to block/reduce the reflector edge diffraction from degrading the plane wave in the test zone, the manufacturing cost is very low. However, the design is much more difficult since the convex nature of the circular reflector rim diffracts more stray signal into the test zone. Thus, the R-card fence should be carefully designed all around the reflector rim. The optimum continuous resistance distribution is replaced by a discretized one to result in lower cost. The R-card design, that reduces the variations in the test zone for a reflector with a circular rim, will be presented in this paper. Calculated and measured results will be shown for the proposed design.
This paper is focused on a recent installation of a probe array for direct far-field. measurement. Such an array has been installed in a well-established compact antenna test range at CNES called BCMA in Toulouse, France. It describes the interests of using such multi-sensor approach for characterizing directive antennas within far-field conditions without any mechanical movements. The paper shows how this facility has been dimensioned for operating over frequencies ranging from 7 GHz up to 15 GHz. Performances and general descriptions of both the probe array and its associated instrumentation will be given. A specific calibration procedure that has been studied and implemented is discussed and finally preliminary results are shown.
Modern Satellite Antennas and Payloads are characterized by a lot of physical parameters like e.g. Radiation Pattern, Gain, EIRP, Flux Density, Gff and PIM, whereas the available time frame for measurements is getting shorter and shorter. The DSS Compensated Compact Range (CCR) allows a time efficient measurement of all payload parameters with high accuracy under controlled environmental conditions. The CCR consists of two doubly curved reflectors, which prevent inherent cross-polarization and create a very high constant amplitude and phase distribution in the quiet zone with a very good scanning performance. Most of the payload parameters can be measured directly or have to be calculated from a set of measurement values. For the G/T measurement of active antennas a new method for the noise power measurement was established. This paper describes the principle test set-ups with the corresponding measurement techniques to improve the measurement accuracy. Error budgets will be presented for pattern and gain measurement.
A compact range based measurement system for automotive radars is presented. The design driver for the system was production testing. Key characteristics of the system are: compact size, short test times, no need for an anechoic chamber, ease of operation, mobility and ruggedness. The measurement system is based on electronic equipment from Dornier GmbH, the company who developed the automotive radar for the new Mercedes S-Class. It uses a small rolled edge millimeter wave compact range from ORBIT/FR Europe GmbH. Some general characteristics of automotive radars are presented, followed by a more detailed description of the key subsystems of the measurement system: Simulator, Compact Range and Processing Control Unit. Finally some measurement results are presented and discussed.
Uncertainty analysis for fundamental standards is mature, but the cost overhead has, until recently, prevented much of this work being taken up by the UK RCS measurement community. The requirement to verify the radar signature of new equipment has made it necessary to examine in detail the RCS measurement process and to create a methodology for error budgeting. The paper reviews some basic concepts in estimating uncertainties, and describes work on 'squat' cylinder calibration standards that have been manufactured following designs proposed at previous AMTA conferences. The moment method code CLASP has provided the basic theoretical solutions which have been verified on a compact range through reference to a precise 100mm spherical standard. The concept of multiple standard calibrations is discussed, and recommendations are made for overall error budgeting and the intercomparison of range types.
A nonparametric, two-dimensional spectral estimation algorithm, based on adaptive decomposition using the reweighted minimum norm method, is applied to ISAR imaging. This paper will describe the algorithm and demonstrate its performance using numerical simulations and compact range measurements. It will be shown that the technique can provide robust isolation and extraction of target and/or contamination returns in situations where these returns would not be resolvable using conventional Fourier imaging techniques.
Time domain (TD) antenna measurements have been successfully implemented in far field ranges [1,2]. The short acquisition times and the wide-band nature of the measurements make this regime a potential alternative to classical frequency domain measurements. Due to the measurement versatility offered by compact ranges, the implementation of TD measurements becomes especially attractive. This paper presents the modelling of the compact range performance in TD. In addition, a statistical evaluation criterion to assess the quiet zone quality is formulated. The results obtained show that this type of measurements can be successfully implemented in compact ranges.