After a brief history of near-field antenna measurements with and without probe correction, the theory of near-field antenna measurements is outlined beginning with ideal probes scanning on arbitrary surfaces and ending with arbitrary probes scanning on planar, cylindrical, and spherical surfaces. Probe correction is introduced for all three measurement geometries as a slight modification to the ideal probe expressions. Sampling theorems are applied to determine the required data-point spacing, and efficient computational methods along with their computer run times are discussed. The major sources of experimental error defining the accuracy of typical planar near-field measurement facilities are reviewed, and present limitations of planar, cylindrical, and spherical near-field scanning are identified.

An overview of near-field antenna measurements

Reverberation chambers are becoming a popular alternative testing facility for a wide range of electromagnetic applications. Because of the statistical environment created inside a reverberation chamber, they offer a unique test facility. In particular, these chambers are ideally suited for performing radiated power measurements of either an antenna or device under test, and as such, it is possible to determine the efficiency of antennas. There have been several reverberation chamber techniques proposed over the years for measuring the antenna efficiency; however, these techniques require either the use of a reference antenna (i.e., an antenna with a known efficiency) and/or require the assumption that the two antennas used in the test have identical efficiencies. In this paper, we present three different approaches for determining both the radiation and total efficiencies of an unknown antenna that overcome these limitations and assumptions. We present a one-antenna approach, a two-antenna approach, and a three-antenna approach. We present measured data for three different antennas in order to compare these three approaches. We also discuss the uncertainties related to these types of measurements.

Reverberation Chamber Techniques for Determining the Radiation and Total Efficiency of Antennas

It is well-known that the far field of an arbitrary antenna may be calculated from near-field measurements. Among various possible nearfield scan geometries, the planar configuration has attracted considerable attention. In the past the planar configuration has been used with a probe scanning a rectangular geometry in the near field, and computation of the far field has been made with a two-dimensional fast Fourier transform (FFT). The applicability of the planar configuration with a probe scanning a polar geometry is investigated. The measurement process is represented as a convolution derivable from the reciprocity theorem. The concept of probe compensation as a deconvolution is then discussed with numerical results presented to verify the accuracy of the method. The far field is constructed using the Jacobi-Bessel series expansion and its utility relative to the FFT in polar geometry is examined. Finally, the far-field pattern of the Viking high gain antenna is constructed from the plane-polar near-field measured data and compared with the previously measured far-field pattern. Some unique mechanical and electrical advantages of the plane-polar configuration for determining the far-field pattern of large and gravitationally sensitive space antennas are discussed. The time convention exp ( j \omega r ) is used but is suppressed in the formulations.

A plane-polar approach for far field reconstruction from near-field measurements

This paper discusses the techniques in antenna measurements and facilities which have evolved over the last decade. The facilities include the tapered anechoic chamber, the compact range, and the near-field probing range. The significant advances in obtaining improved measurement accuracy for power gain, polarization, and swept-frequency techniques are also discussed.

Antenna measurements&#8212;1978

Foreword. Preface. Acknowledgments. Contributors. Chapter 1. Introduction (William A. Imbriale, John Huang, and Mark S. Gatti). 1.1 Technology Drivers (William A. Imbriale). 1.2 Analysis Techniques for Designing Reflector Antennas (William A. Imbriale). 1.3 Wire Antennas (William A. Imbriale). 1.4 Microstrip Antenna: Analysis, Design, and Application (John Huang). 1.5 Antenna Measurements (Mark. S. Gatti). References. Chapter 2. The Early Years (William A. Imbriale). 2.1 Explorer 1. 2.2 Pioneers 3 and 4. 2.3 Project ranger. 2.4 Surveyor. References. Chapter 3. The Planetary Flybys (William A. Imbriale). 3.1 The Mariner Series. 3.2 Voyager Mission to the Outer Planets. References. Chapter 4. The Mars Missions (Joseph Vacchione). 4.1 Overview of Missions to Mars. 4.2 NASA Mars Orbiters/Landers. 4.3 Mars Rovers. 4.4 Continued mars Exploration. References. Chapter 5. The Orbiters (William A. Imbriale, Mark S. Gatti and Roberto Mizzoni). 5.1 Magellan to Venus (William A. Imbriale). 5.2 The Galileo Antenna System (Mark S. Gatti). 5.3 The Cassini High-Gain Antenna Subsystem (Roberto Mizzoni). References. Chapter 6. Spaceborne SAR Antennas for Earth Science (Yunjin Kim and Rolando L. Jordan). 6.1 Introduction. 6.2 Characteristics of Spaceborne Earth Science SAR Antennas. 6.3 Seasat, SIR-A, and SIR-B Spaceborne Antennas. 6.4 SIR-C and SRTM Antennas. 6.5 Future Antenna Technologies and Concluding Remarks. References. Chapter 7. Instrument Packages (Richard E. Cofield, William A. Imbriale and Richard E. Hodges). 7.1 Radiometers (Richard E. Cofield). 7.2 Microwave Limb Sounders (MLS) (Richard E. Cofield). 7.3 Earth Observing System (EOS) MLS (Richard E. Cofield). 7.4 Scatteromeeters (Richard E. Cofield). 7.5 CloudSat (William A. Imbriale). 7.6 Wide Swath Ocean Altimeter (Richard E. Hodges). 7.7 Summary (Richard E. Cofield). References. Chapter 8. Mechanical Development of Antenna Systems (Gregory L. Davis and Rebekah L. Tanimoto). 8.1 Historically Significant Antenna Systems. 8.2 Current State-of-Practice. 8.3 Antenna Technology Development. 8.4 Future Antenna Systems Developments. 8.5 Concluding Remarks. References. Chapter 9. Miscellaneous Other Antennas (William A. Imbriale and Daniel J. Hoppe). 9.1 Solar Probe Antenna (William A. Imbriale). 9.2 Deep Impact S-Band Patch Array Antenna (Daniel J. Hoppe). References. Chapter 10. Spacecraft Antenna Research and Development Activities Aimed at Future Missions (John Huang). 10.1 Inflatable Array Antenna. 10.2 Foldable Frame-Supported Thin-Membrane Array. 10.3 Thin-Membrane Array Antenna for Beam Scanning Application. 10.4 Printed Reflectarray Antenna. 10.5 Applications and Recent Developments. 10.6 Summary. References. Acronyms and Abbreviations.

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Spaceborne antennas for planetary exploration

A new technique is described for determining power gain and polarization of antennas at reduced range distances. It is based on a generalized three-antenna approach which, for the first time, permits absolute gain and polarization measurements to be performed without quantitative a priori knowledge of the antennas. The required data are obtained by an extrapolation technique which includes provisions for rigorously evaluating and correcting for errors due to proximity and multipath interference effects. The theoretical basis provides a convenient and powerful approach for describing and solving antenna measurement problems, and the experimental method employed illustrates the utility of this approach. Examples of measurements are included which exhibit errors in gain as small as \pm0.11 dB ( 3\sigma ).

P. Wacker

Papers

Accurate measurement of antenna gain and polarization at reduced distances by an extrapolation technique