AMTA Paper Archive


Welcome to the AMTA paper archive. Select a category, publication date or search by author.

(Note: Papers will always be listed by categories.  To see ALL of the papers meeting your search criteria select the "AMTA Paper Archive" category after performing your search.)


Search AMTA Paper Archive
    
    




Sort By:  Date Added   Publication Date   Title   Author

RCS

Amplitude and doppler modulation effects in ground to air ISAR data collected with a linear FM waveform
L. Cech,G. Fliss, W. Nagy, November 1994

The utility of high resolution ISAR data in the devel­ opment and maintenance of low observable (LO) and conventional aircraft and the identification and charac­ terization of threat aircraft is well established. However, the task of ISAR image RCS interpretation is difficult. Often imaging effects introduced by rotating blades and jet engine modulation (JEM) can compound the already difficult interpretation task. It is easy for these effects to be obscured, ignored, or erroneously misinterpreted in ISAR down-range versus cross-range (Doppler) imag­ ery and range compressed versus time domain data. This paper presents cases of amplitude and phase modulated ISAR data collected from two airborne targets; a propel­ ler driven airplane and a helicopter, using a linear FM waveform radar. This will be supplemented with mathe­ matical models describing the modulation phenomenon and the resultant imaging effects

Experimental RCS analysis of a communications antenna mounted on a large cylinder
E. Walton,H.W. Tseng, November 1994

The radar scattering from a small communications antenna mounted on a large cylinder was measured at the Ohio State University ElectroScience Laboratory compact range. This paper will describe the experimental measurement techniques and the details of the analysis of the experimental. The small (5 cm) blade/slot/cavity antenna was mounted on a 1.82 meter long cylinder of 0.61 meter diameter. The cylinder was treated with RAM on the ends to reduce the direct and interactive end scattering effects, and was mounted in the OSU compact RCS measurement range. Measurements over the 2 to 18 GHz band both with and without the antenna were made and the results subtracted during the calibration effects to further remove the end effects. We will demonstrate these techniques and evaluate their effectiveness. ISAR imaging of both the antenna and the scattering term associated with the load on the end of the antenna transmission line will be shown. This will demonstrate that the transmission line and loan can be separately evaluated using such techniques. A time frequency distribution (TFD) analysis technique will also be demonstrated as a means of extracting various antenna resonance terms from the data. A description of the theoretical computation of the scattering will also be given and the special aspects of this problem outlined. The theoretical RCS data will be compared to the experimental measurements of the RCS.

Missile control by local reflectivity measurements with spot focusing horn lens antenna
E. Marouby,A. Roussaud, E. Ongareau, J.R. Levrel, November 1994

This paper describes final results on the of non­ destructive measurement methods of missiles in terms of stealthiness. Measurements performed on full scale missiles allow to determine the reflectivity of the material and give estimation of its real RCS with to its nominal RCS. Different measurement techniques are reviewed, based on the use of coaxial transmission line, circular waveguide and spot-focusing horn lens antenna. Modeling, and characterization of spot-focusing corrugated horn lens antennas operating in the frequency range 2 - 18 GHz are presented. Finally, system configuration of full scale missile RCS measurements currently being utilized for production control is presented.

Application of common processing software as a tool for study of component interaction terms in RCS measurements, An
J. Matis,D. Yanke, November 1994

• Some Radar Cross Section (RCS) measurements contain significant contributions from the interaction of test article components. Usually the direct measurement of these terms is difficult. When these terms are not major factors, they need little attention. In other circumstances they should at least be quantified. There terms are often studied with special models, and/or Doppler measurements, and analysis. These relatively expensive methods yield the required information. For some purposes a more economical, limited method would be useful. RCS measurement and analysis facilities use software designed to present data in usable formats, with appropriate processing. This software is often run on a powerful workstation, or mainframe. McDonnell Douglas Technologies Inc. (MDTI) processing software "runs" on an .HP730 series workstation. The speed and capacity of such a system makes processing data a convenient option. MDTI demonstrated the ability to extract interaction terms from an easily acquired data set. This extraction required only the use of standard data software. Results with generic shapes demonstrate the ability to extract terms > 30 dB below the return of the test article specular return

Vertical antenna array applications on a ground-bounce instrumentation radar range
B.E. Fischer, November 1994

A vertical array of antennas is used to beamform the farfield used in the measurement of Radar Cross Section (RCS) on a ground-bounce radar range. By properly weighting (attenuating) and phasing (through line length adjustments) each antenna, a desired far-field pattern can be obtained. This paper discusses some benefits of the technique and outlines a basic mathematical approach. Implementation is considered, and wide band ramifications of a practical design are discussed. At RATSCAT, this basic understanding was used to examine a simple two element array. This paper preceded that study and was originally written just for that purpose.

Waveform chirp speed effects on modulation artifacts in radar imagery
G. Fliss,D., Jr. Kletzli, W. Nagy, November 1994

Typical high-resolution dynamic target imaging radars have frequency scan rates that do not properly sample the modulation from rotating structures such as aircraft propellers, engine turbines and helicopter blades. This results in the scatterer modulation energy being aliased. Moreover, if the chirp rate is too slow blurring and of the scatterer can occur in the image. Often the utility of this data for RCS signature analysis is questioned. This paper addresses the utility of images generated from undersampled data of modu­ lating scatterers. Experimental results using various combinations of chirp scan, modulation, and target-body rotation rates are presented. Fast scan rates, typical of the Linear-FM waveform, are compared to the slower scan rates commensurate with step frequency wave­ forms. Images are shown illustrating how the different chirp speeds alter the two-dimensional image of a mod­ ulating target.

Practical aspects of 3D imaging
D. Flynn,S. Pressnall, November 1994

ISAR imaging has proved to be a _ significant diagnostic tool for the evaluation of RCS signatures because of its ability to resolve scatterers in both the cross range and down range dimensions. There is a growing desire to extend the imaging capability to include the vertical dimension of a target, or three­ dimensional (3D) imaging. Several techniques have been suggested with varying degrees of success and complexity. These techniques include triangulation from two or more ISAR images of the same target taken at different elevation angles, tomographic algebraic reconstruction, and true 3D ISAR imaging using the FFT. Each technique requires progressively more data and more complex algorithms, but results in more resolution. This paper examines these various techniques, and evaluates their advantages and disadvantages based on actual implementations using simulated data.

Clutter mapping system
J.F. Aubin,C.T. Nadovich, November 1994

A proper knowledge of clutter characteristics is critical to the design, development, and test of military seeker and radar hardware. The Clutter Mapping System under construction at Flam & Russell, Inc. is simple yet powerful tool for the evaluation of potential radar sites or the analysis of current sites. It provides a maximum 40 foot synthetic aperture that can image a 60 degree sector of terrain out to a 20 mile range and beyond. Aside from this primary mission, it has the capability to perform RCS measurement of non-cooperative ground targets or to serve as a tactical, quickly deployed imaging system. Totally self contained, and transportable, this system can fulfill a wide variety of RCS measurement needs.

Qualified and high performance test results of the cylindrical outdoor near-field test range
H-J. Steiner,A. McCormick, J. Habersack, J.R. Holloway, T. Fritzel, T. Jakob, November 1994

One of the world's most sophisticated antenna test ranges is now fully operational. This was designed by the Deutsche Aerospace (DASA) and is operated by Siemens Plessey Systems (SPS). The presented paper will describe the pioneering design philosophy adopted to ensure the stringent performance features. Although this facility is located outside, it allows extremely high precision probing of cylindrical near field of large and very complex antenna systems, with turning diameters up to 16 meters and up to 20 GHz. Besides the RCS optimized 36 m large scanner tower the significant highlights of this facility consist of a comprehensive air-conditioning system for all accuracy dependent components, a permanent autoalignment system, which ensures high precision cylindrical measurements and an interleaved high speed data collection system, which delivers a maximum of data performance within a minimum time frame. Test results including a pattern comparison of the Ref­ erence Antenna between measurements in DASA facilities and the SPS Cylindrical Near-Field Test Facility show good range performance. The evaluation of the range performance data demonstrates the measurement integrity of the facility and proves to be qualified to characterize a wide range of antennas.

Automated test sequencer for high volume near-field measurements, An
G. Hindman,D. Slater, November 1993

Test sequencing flexibility and high throughput are essential ingredients to a state-of-the-art near-field test range. This paper will discuss methods used by NSI to aid the operator through the near-field measurement process. The paper will describe NSI's expert system and customer applications of a unique test and processing sequencer developed by NSI for optimizing range measurement activities. The sequencer provides powerful control of software functions including multiplexed measurements, data processing and unattended test operations.

Portable RCS diagnostic system
R. Harris,B. Freburger, D. Maffei, R. Redman, November 1993

This paper describes the most recent version of the Model 200 portable RCS diagnostic radar. The Model 200 was designed to provide high-resolution RCS measurements in unprepared rooms indoors as well as on outdoor ranges. The system can provide real aperture measurements, ISAR measurements, or SAR measurements without changing system configuration.

Measurement speed and accuracy in switched signal measurements
J. Swanstrom,R. Shoulders, November 1993

The interdependence of accuracy and speed should be considered when analyzing measurement requirements. Tradeoffs can be made to optimize the measurement when accuracy is of primary importance, or where speed is critical. Several different measurement modes of the HP 8530A Microwave Receiver are presented, each with different measurement speed and accuracy tradeoffs. Examples are given that illustrate which acquisition modes would be appropriate to optimize the acquisition speed and accuracy in a variety of applications

Superresolution ISAR imaging techniques
E. Walton,I.J. Gupta, November 1993

This paper demonstrates modem parametric modeling techniques that can be used to form high resolution ISAR images of full scale flying aircraft. Both parametric spectral estimation techniques and autoregressive data extrapolation techniques are shown. We demonstrate imaging. In each case, the modem spectral estimation or data extrapolation techniques produce higher image resolution than that which is obtained by classical Fourier techniques.

Scattering by a simplified ship deckhouse model
C.R. Birtcher,E.R. Bonsen, J.T. Aberle, November 1993
Remote thickness sensor
W.S. Arceneaux, November 1993

Applications that require tight tolerances on dielectric thickness control need accurate sensors. A technique has been developed that will allow for the measurement of thickness without requiring surface contact. High resolution radar imaging, commonly used in RCS measurements , is now being used to measure thickness. Electromagnetic fields reflected from the front and rear surface are detected and the time response delta is converted into thickness. A major advantage of this method is that it is not affected by varying sensor offset height.

Portable RCS diagnostic system
R. Harris,B. Freburger, D. Maffei, R. Redman, November 1993

This paper describes the most recent version of the Model 200 portable RCS diagnostic radar. The Model 200 was designed to provide high-resolution RCS measurements in unprepared rooms indoors as well as on outdoor ranges. The system can provide real aperture measurements, ISAR measurements, or SAR measurements without changing system configuration.

Ground-to-air RCS diagnostic system
R. Harris,A. Strasel, B. Freburger, C. Zappala, M. Lewis, R. Redman, November 1993

The initial phase of METRATEK's new Model 300 Radar System has been installed at the Navy's Chesapeake Tests Range (CTR) at Patuxent River, MD. This ground-to-air Multimode, Multifrequency Instrumentation Radar System (MMIRS) is a high-throughput frequency-and-polarization agile radar that is designed to drastically reduce the cost of measuring the radar cross section of airborne targets by allowing simultaneous measurements to be made at VHF through Ku Band.

High duty instrumentation radar transmitters
F.A. Miller, November 1993

Today's requirements for dynamic Radar Cross Section (RCS) test data set new demands upon instrumentation Radar systems. Transmitters must deliver high power and operate at high data rates. Additionally, noise floor reduction of coherent spurious signals improves raw data and minimizes the need for manipulation of data.

Demonstration of bistatic electromagnetic scattering measurements by spherical near-field scanning, A
M.G. Cote,R.M. Wing, November 1993

The far-field radar cross section (RCS) of a conducting sphere is obtained by transforming scattered near-fields measured on a spherical surface. A simple and convenient calibration procedure is described that involves measuring the incident field directly at the target location. Although a non probe-corrected transmission formula was used in this study the importance of prove correction in practice is demonstrated.

Vertical bistatic RCS measurements in the MDTI radar measurement center
J.,D. Weatherington, November 1993

This paper demonstrates vertical bistatic Radar-Cross-Section measurement capability in the McDonnell Douglas Technologies, Inc. (MDTI) Radar Measurement Center )RMC). Data will be presented showing the system configuration, system specifications, and predicted and measured vertical bistatic RCF data on a variety of generic targets.







help@amta.org
2024 Antenna Measurement Techniques Association. All Rights Reserved.
AMTA_logo_115x115.png
 
 

CONNECT WITH US


Calendar

S M T W T F S
1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31