1989 Technical Papers

A High Speed Microwave Measurement Receiver

Author: William. Tuttle
Publication: AMTA 1989 
Copyright Owner: NSI-MI Technologies

In order to justify the expenditure for capital equipment such as a microwave receiver, it must be shown that the instrument provides the best value to the user. The best value for a microwave receiver for measuring today’s complex microwave antennas dictates that the receiver be versatile enough to adapt and operate over a diverse set of applications and performance specifications. Some important characteristics to consider when evaluating a microwave receiver’s value is measurement speed, frequency agility, number of measurement channels, remotability, dynamic range, ease of operation, and system integration.

This paper addresses the development and important characteristics of a high speed microwave receiver that was designed to provide users with maximum productivity, and therefore, the best value for a microwave antenna measurement receiver. Receiver characteristics such as acquisition speed, frequency agility, number of measurement channels, controls, interfacing, and versatility are discussed.

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A Low Cost Portable Near-Field Antenna Measurement System

Authors:  Dan Slater, Greg Hindman
Publication: AMTA 1989 
Copyright Owner: NSI-MI Technologies

Implementing an antenna test range has traditionally been viewed as a major and costly undertaking, requiring significant long term facility planning, computer hardware interfacing, and software development. This paper describes a complete low cost, yet high accuracy portable near-field measurement system that was privately built for less than $2,000 and interfaced to a PC compatible computer.

The design and operation of this system, including the scanner, microwave hardware, and computer system will be described. This system has since been extended into a commercial product capable of providing rapid and accurate measurements of small to medium size feeds and antennas within a small office or lab space at significantly lower cost than standard antenna test techniques. The system has demonstrated an equivalent sidelobe noise level of less than -50dB, includes a probe corrected far-field transform and holographic back projections, and can output pattern cuts, contour plots, 3D plots, and grey scale images of antenna performance.

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A Wideband RF Feed for RCS Compact Range Facilities

Authors: Kevin Miller, William Swarner
Publication: AMTA 1989 
Copyright Owner: NSI-MI Technologies

Compact range facilities designed for RCS measurements have exhibited a performance-limiting effect commonly referred to as "feed ringing". "Feed ringing" is a phenomenon in which energy is stored in or about the RF feed structure and is sustained for a sufficient period of time after the source is turned off such that its presence contaminates the true target return. This effect has placed severe constraints on the design of the RF feed for the compact range, particularly in regard to its operating bandwidth. This paper presents the design of a lossless, waveguide type RF feed suitable for compact range application with a demonstrated useful bandwidth approaching a full octave.

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Error Suppression Techniques for Near-Field Antenna Measurements

Authors: Dan Slater, Greg Hindman
Publication: AMTA 1989 
Copyright Owner: NSI-MI Technologies

This paper describes techniques for coherently suppressing multipath and other error sources in planar near-field measurements. Of special interest is a simple, yet effective technique for suppressing axial multipath and mutual coupling between the near-field probe and an antenna. This is of particular value in the testing of low sidelobe antennas. Traditionally, self comparison tests with different separations between the probe and the antenna under test are used to identify the magnitude of multipath errors. What is not generally realized is that these tests can be used to produce a coherent estimate of the induced error, which can often be suppressed. A series of tests was performed with a small X-band phased array antenna, resulting in a reduction of the sidelobe noise background from a 25dB level to better than 50dB.

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Guided Weapons Radar Testing

Author: Richard H. Bryan
Publication: AMTA 1989 
Copyright Owner: NSI-MI Technologies

An overview of non-destructive real-time testing of missiles is discussed in this paper. This testing has become known as hardware-in-the-loop (HIL) simulation because it involves the actual missile hardware.

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Hand Held Microwave Reflectometer

Authors: Dan Slater, Greg Hindman
Publication: AMTA 1989 
Copyright Owner: NSI-MI Technologies

Measurements of the microwave reflectivity of materials is often performed with complex test setups using probes attached to a vector network analyzer. The lack of portability of these systems prevents the user from measuring reflective properties of surfaces that are not easily moved to an appropriate test facility. This paper describes a small, hand held microwave reflectometer which is designed to perform rapid reflectivity measurements in the field. The reflectometer consists of a tuneable Ku band source, a dual polarization sampling horn, a pair of crystal detectors, and a battery powered microcomputer.

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High Speed, Multi Frequency Measurements

Authors: 0. M. Caldwell
Publication: AMTA 1989 
Copyright Owner: NSI-MI Technologies

Precise and complete measurements of advanced electromagnetic systems demand dramatically higher data acquisition speeds than those commonly attainable. Specific challenges include requirements for wideband measurements with arbitrarily spaced frequency steps. These types of measurements are often encountered in characterizing EW/ECM systems, radars, communications systems, and in performing antenna and RCS measurements.

The MI Technologies Model 1795 Microwave Receiver offers capabilities directly applicable to solving measurement problems posed by highly frequency agile systems. These problems include:

  1. timing constraints
  2. data throughput
  3. RF interfacing
  4. maintaining high accuracy

A technique is discussed which shows the application of the Model 1795 Microwave Receiver in its high frequency agility mode of operation. Measurement examples are presented showing the advantages gained compared to previous methods and instrumentation configurations.

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Improving Antenna Test Range Productivity

Author: James D. Huff
Publication: AMTA 1989 
Copyright Owner: NSI-MI Technologies

This paper presents the productivity improvements that are possible in complex antenna measurements using state of the art instrumentation. The productivity improvement is calculated for a hypothetical antenna, and from this productivity improvement manufacturing cost reductions and payback times are derived.

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Virtual Vertex Compact Range Reflectors

Authors:James D. Huff
Publication: AMTA 1989 
Copyright Owner: NSI-MI Technologies

In an earlier paper the virtual vertex compact range reflector was introduced and data from a specific design was reported. This paper describes the extension of the virtual vertex serrated edge concept to other reflectors that serve a wider range of application. Two new 12 ft focal length reflectors have been built that possess 3 ft and 6 ft diameter symmetric test zones. We describe the electromagnetic considerations and the mechanical design approach that has been used for these reflectors. We demonstrate the performance with field probe data showing the excellent surface accuracy of these units.

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