AMTA Paper Archive
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AMTA Paper Archive
Automated Near-Field Antenna Test Set for Phased Array Production
The AEGIS AN/SPY-1A antenna system is an S-band monopulse phased array system designed for monopulse operation. Its high performance and manifold capabilities have placed stringent demands on the test system used in its evaluation. This paper will describe the AEGIS Near-Field Antenna Test Set (ANFATS) currently being implemented for acceptance testing production models of the antenna, a system designed for operation by manufacturing test personnel
Antenna Polarization measurements
In recent years there has been an increasing requirement for more extensive and precise measurements of the polarization properties of antennas. Some of the more conventional polarization measurement techniques are no longer applicable because of the required measurement time or the achievable accuracy. This presentation is an overview of polarization measurement methods which may be employed on far-field antenna ranges. Instrumentation requirements and sources of error are also included.
Antenna Range Test and Evaluation of Active Optical Weapons Systems
A novel application of the variable-range outdoor antenna measurement system is the test and evaluation of various active optical weapons systems such as missile and projectile fuses. These devices are tested as optical-wave length antennas. The entire test program, including positioning, stimulus and measurement, is performed under computer control by the SA 2021A Automatic Antenna Analyzer. Outdoor testing of optical weapons system affords the opportunity to evaluate the effectiveness of various countermeasure and counter-countermeasure techniques.
IEEE 488 System Concepts
This paper will present a basic explanation of the IEEE Standard 488-1978, concerning what it is, and how and why it concerns people in the RF world. In addition, the practical side of the IEEE 488 will be discussed, touching on such topics as the types of instrumentation available with IEEE, custom systems design and installation, the new one-chip interfaces, computer enhancement of measurements and generation of analytical graphic data. This up dated review is made with an eye towards enhancing both speed and accuracy of contemporary antenna testing techniques.
Adaptive antenna measurement techniques
The objective of this paper is to outline test procedures, test set-up, and antenna measurements collected on a multi-element adaptive antenna processor. The elements used are UHF blade antennas located on a pedestal mounted A-10 aircraft at the RADC Newport Test Range. The measurement data to be presented will include basic element, and adaptively weighted element patterns. Methods of interpreting system performance and problems in collecting the data will also be provided.
RADC's Newport antenna test facility
Today I would like to describe this unique antenna Test Facility and its background, capabilities, typical tests and problem areas.(Figure 1) First of all by way of introduction: I’m in the Test and Evaluation Branch of the Rome Air Development Center (RADC). We are an R&D laboratory under the Air Force Systems Command. RADC’s prime mission is R&D in the area of Command, Control, Communication and Intelligence often referred to as C3I. We are located at Griffiss AFB which is in the City of Rome, in the center of beautiful upstate New York. The outdoor antenna range which is the subject of this briefing is at the RADC Newport Test Site is located about 30 miles east of Griffiss in the foothills of the Adirondack mountains.(Figure2)
Digital Antenna Data Collecting System for MIL-A-87136 Testing
The Defense Electronic Supply Center in Dayton, Ohio has recently issued a specification, MIL-A-87136, for testing Airborne Antennas. This specification covers all aspects of testing antennas including a section dealing specifically with radiation pattern tests. Further, this specification defines the data format to be used when antenna pattern measurement data is required to be furnished on magnetic tape. Scientific-Atlanta’s Series 2030 Antenna Data Collection System’s magnetic tape format and test instrumentation meets the requirements set forth in MIL-A-87136. The system is a complete instrumentation/firmware package designed and programmed to perform commonly made antenna pattern measurements. After initial operator set-up, measurements can be made automatically at frequencies in the 1-18 GHz range. The test results are digitally recorded on magnetic tape and may be displayed as radiation distribution plots, data listings, or as conventional data patterns. The presentation describes the Antenna Data Collection System, its application to automatic antenna testing and to the requirements of MIL-A-87136. Features of the Data Collection System are included, as well as advantages of automatic measurement and digital recording of antenna data.
E-2C APS-125 Radar In-Flight Antenna Measurement Techniques
The E-2C Hawkeye aircraft is a carrier based airborne early warning sensor platform. The primary sensor is the APS-125 radar which is operated in the 400 to 446 MHz frequency range and utilizes a 10-element, Yagi end-fired array antenna integrated into a rotating, 2,400 pound rotodome mounted on top of the E-2C aircraft. As is the case for most airborne antennas, the performance in free space when the antenna is off the aircraft can be readily measured on a ground antenna range, but the accurate measurement of the antenna’s performance under actual flight conditions presented project engineers with a unique problem: Pattern interaction between the rotating rotodome and the aircraft fuselage and turning propellers could not be evaluated using existing ground range facilities. The proposed improvements to these facilities to accomplish this task were estimated to cost in excess of five million dollars.
IEEE-488 compatible positioner programmer
Automatic testing is becoming more and more prevalent in the antenna measurement field. With this new technology, the antenna test engineer is faced with the problem of controlling the antenna test positioner system automatically. Automatic operation may simply consist of driving the test positioner axes to make several scans of a test antenna; or it could involve complete computer control of a multi-axis positioning system to perform a complex routine. This presentation discussed a positioner programmer designed to meet these requirements. The 2012 can be programmed from its front panel to perform common position and raster scan routines. Using the IEEE-488 interface bus, the programmer will accept commands from a digital calculator or computer to control up to six (6) axes of motion through any desired sequence of operation. During record scans, the 2012 will output commands at selected angular intervals to allow the digital processor to update and read measurement instruments and perform other functions such as tuning signal sources and receivers. Various features, options, and accessories for the 2012 enhance its overall flexibility and compatibility in the antenna measurement system.
Economy of Near Field Antenna Measurements
Near field antenna measurements have long been of interest to the antenna community and of particular interest to those in the design and measurement of antennas. Efforts in this area using analog computers for data reduction were already under way in the late 1950’s. These applications were limited, primarily due to the limitations of the analog computer. Two planar near field probe positioners were built by Scientific-Atlanta during this period and delivered; on to Martin Denver and one to the Georgia Institute of Technology. These units were used for development on planar near field measurements. The unit at Martin Denver was also used by the Bureau of Standards. Experimental work at Georgia Tech led to Dr. Joy’s thesis on spacial sampling and filtering.1 This work on sampling was particularly important because it gave an understanding of the required data density for meaningful transformation by digital computer. Numerical integration is a time and core intensive process and it was the utilization of the Fast Fourier Transform in the early 1970’s that made the digital computer a viable approach to the problem.
Remote Control of Source Functions Over Medium Length Antenna Ranges
Methods of remotely controlling source transmitters and antennas over long distances is described. The remote range controller instrumentation currently available is limited to a 5.5 mile separation, over voice grade telephone lines. Unfortunately the phone line routes are not line of sight. In fact, the most direct route available for source control over dedicated phone lines at the Westinghouse antenna range complex is 13 miles in length. We wanted to utilize the Scientific Atlanta Model 4580 Remote Range Controller since it is fully compatible with out existing signal sources, programmable receivers and positioner controls. However, the data set available with the Model 4580 is limited to 5.5 miles separation between the master control unit and the remote control unit. The data set requires four wires or two dedicated phone lines. Transfer speed is 0-9600 bits per second asynchronous. The solution to overcome the 5.5 mile limitation and permit full use of the Model 4580 capabilities is described. Lightning protection and alternate control methods using tone controls over phone lines and method of employing a microwave link is discussed.
Scale Model Shipboard Antenna Measurements with a Computer Automated Antenna Analyzer System
This paper discusses some of the more unique problems involved in the performance of measurements on a ground plane type of antenna range generally required for the study and design of multiple antenna shipboard systems. The discussion concentrates on the installation and use of a computer automated antenna analyzer system on this type of range. The methods and results of various range calibration measurements are presented with emphasis on the use of the system’s computerized capability to perform measurements, analyze data, and produce various graphic output formats. The test results obtained from a pair of monopole antennas mounted on a simplified model ship hull are also presented and discussed.
Standard antenna measurement systems
In the area of antenna measuring, there are many components offered that are useful in testing antennas. Placing the proper components together in a system that performs one’s desired results can be difficult. The results may leave no room for upgrading to a more sophisticated system. Scientific-Atlanta has introduced a new line of antenna measurement systems. This paper describes these manual amplitude and phase/amplitude systems and now they were put together to meet specific needs and allow for future expansion to semi-automatic systems. A survey of automatic systems is included.
Brief history of anechoic chambers for antenna measurements
A review will be made of advances in anechoic chamber technology from the precursors of World War II to the huge complex chamber of today. A glimpse of the technology of the 80’s will be offered.
Estimating the accuracy of gain measurements
A limited number of power gain measurements for some broadband airborne antennas were analyzed by comparing the measured values to the predictions from hypothetical models for the antennas. The difference between the predicted gain and measured gain is defined as the measurement uncertainty. The measurement uncertainties were statistically analyzed to determine the accuracy of the gain measurements. The results indicated that 79 percent of measurement uncertainties were written 1.5dB.
Data processing and display for large quantities of antenna patterns
This paper will briefly describe the RADC Antenna test facilities and their function. Considerable focus will be placed on the large amounts of data generated and the associated requirements for Real Time Data, Digital Data, Data Processing and Display, Quality Control and Fast Turnaround of Data. Also, the current process utilized to satisfy the data requirements will be described, followed by a discussion of techniques presently under development to further enhance the process. The use of 3-D displays with color enhancement will be included.
Computerized antenna measurement system
The Amecom Division of Litton Systems has developed several computerized antenna measurement systems designed to make the so-called standard antenna measurements plus relative and absolute phase and amplitude measurements of interferometer arrays. This paper will outline computerized measurement techniques for VSWR, swept phase and amplitude (vs) frequency (multi-octave bandwidths), phase and amplitude (vs) azimuth, radiation patterns and gain. The new computerized systems have reduced production system measurement time by 80 percent.
Antenna pattern data acquisition
This data acquisition and pattern analysis system uses a standard set of Scientific Atlanta antenna-pattern-taking equipment as the basic operational gear. A Tektronix 4051 or 4052 Graphic System is used as a controller to operate the S/A gear and to obtain and store output data in digital format. The TEK 4051 does this by use of the IEEE General Purpose Interface Bus (GPIB), to which three interface boxes are connected. These three: • HP-59306A Relay Actuator • Model 4883 ICS Instrument Coupler • HP-3455A Digital Voltmeter message or digitize the S/A data and put it on the GPIB lines.
Scale model aircraft antenna measurements
Antennas are an integral part of the communications, navigation, EMC systems installed on aircraft. Aircraft, such as the Douglas DC-9, C-9A, C-9B, DC-10, KC-10A, A-3 and A-4, use approximately 20 antennas. These antennas operate from VLF to approximately 20 GHz. The radiation patterns of these antennas are affected by aircraft structure such as wings, vertical stabilizer, engines, and landing gear. Douglas Aircraft Company measures the radiation patterns of these antennas using scale model aircraft (and/or aircraft sections) to predict the performance of the associated system. This paper describes some of the scale model measurement techniques used by Douglas Aircraft Company to obtain scale model radiation pattern data.
A Laboratory application of structured analysis and design
The changeover of personnel in some laboratories has historically resulted in high costs for software maintenance. These high costs can be traced to poor documentation of the analysis and design process during the software development. This paper illustrates the structured analysis and design methodology used to analyze, design, and implement software to automatically test performance of an Air Force advanced development communications system. The requirements definition and preliminary design are accomplished using activity models to represent the functions performed during the test. The development of the activity models is the vehicle used to do a thorough requirements definition, while the resulting functional architecture represents an understandable preliminary design. The detailed design is formed using structure charts which better reveal system characteristics that illustrate design quality. The structure charts also facilitate the coding of the software to be implemented. The combination of activity models and structure charts provide the detailed documentation of the software analysis and design phases that are required to ensure ease of maintenance, broadening of understanding, and most importantly, a complete development package that can be passed on to a new user. These features ultimately result in a significant reduction in long term maintenance costs.
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