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Electromagnetic Measurements

Electromagnetic Field Strength and Antenna Measurements

Microwave Antenna Parameter Measurements

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Technical Contacts:
Perry F. Wilson
(63100S-63400S) 
Tel: 303-497-3406
E-mail: pfw@boulder.nist.gov

Jeffrey Guerrieri
(63100S)
Tel: 303-497-3863
E-mail: jeffrey.guerrieri@nist.gov

Michael H. Francis
(63200S)
Tel: 303-497-5873
E-mail: francis@boulder.nist.gov

John Lomax
Administration and Logistics
Tel: 303-497-3842
Fax: 303-497-4286
E-mail: john.lomax@nist.gov

Please contact the administration and logistics staff before shipping instruments or standards to the address listed below.

Mailing Address:
National Institute of Standards and Technology
M.C. 818.02
325 Broadway
Boulder, CO 80305-3328

Service ID
Number
Description of Services Fee($)
63100S Gain and Polarization Calibrations of Standard Antennas Using Extrapolation Range At Cost
63200S Measurement of Pattern,Gain, and Polarization of Arbitrary Antennas Using Near-Field Scanning Techniques At Cost
63400S Special Consulting, Advisory, and Other Services At Cost
Fees are subject to change without notice.

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Antenna Parameter Measurements (Microwave)-General Information

Accurate measurements of antenna gain, pattern, and polarization are generally available from about 1 GHz to about 75 GHz. However, because the measurement accuracy, capability, and cost depend on the frequency, type, and size of antenna, and the parameters to be measured, a particular measurement service must be negotiated in advance. Antennas submitted for evaluation should be mechanically and electrically stable in order to retain a calibration for a significant length of time. Antennas with either coaxial or waveguide connectors can be measured; however, if coaxial connectors are employed, they should be precision connectors to minimize uncertainties due to a lack of connector repeatability. In particular, the use of SMA and APC-7 connectors is strongly discouraged because of poor connector repeatability. The following methods and facilities are used for these measurements.

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Gain and Polarization Calibrations of Standard Antennas Using Extrapolation Range (63100S)

This calibration service is offered primarily for determining the absolute on-axis gain and polarization of standard gain horns, which, in turn, are used as reference standards in determining the gain and polarization of other antennas by the gain comparison technique. In the extrapolation method, three antennas are normally utilized, and three pairwise combinations are determined. The received signal transmitted between each pair of antennas is measured as a function of the separation distance between the antennas. The antennas need not be identical, and no assumptions concerning the polarization are required. The method is not well suited for pattern measurements but is the most accurate technique known for absolute gain and polarization measurements. For gain measurements from 2 GHz to 30 GHz, the uncertainties are typically 0.10 dB; above 30 GHz, the uncertainties are typically 0.15 dB. Uncertainties of 0.05 dB/dB for polarization axial ratio measurements are typical. There are antenna size limitations associated with existing NIST extrapolation ranges. These limitations depend on the type of antenna, the frequency, and the desired measurements and accuracies. Therefore, negotiations must be conducted prior to submitting antennas for calibration to ascertain whether all requirements can be met.

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Measurement of Pattern, Gain, and Polarization of Arbitrary Antennas Using Near-Field Scanning Techniques (63200S)

With this technique, gain, pattern, and polarization parameters are calculated from near–field amplitude and phase measurements taken over a surface close to the test antenna. The absolute gain can be determined to within about 0.2 dB, the polarization axial ratio to within about 0.10 dB/dB, and side lobe levels can be obtained down to -50 dB or -60 dB. The exact uncertainties in these parameters will depend on such factors as the frequency, type and size of antenna. Antennas with apertures up to about 3 m in diameter can be managed. Measurements can be made from about 1 GHz to about 75 GHz. Measurements are most commonly made over a plane surface in front of the antenna being evaluated, but the capability also exists for measuring over a cylindrical or spherical surface surrounding the antenna when it is advantageous to do so. Calibrated probes are normally required for these measurements. These near-field scanning measurements are offered as a special-est service because nearly every measurement is unique and it is difficult to build up a statistical history as required for a regular calibration service.

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Special Consulting, Advisory, and Other Services (63400S)

A variety of special consultation and advisory services related to the measurements described above are available upon request. These services are offered to disseminate NIST technologies and to assist other organizations in establishing their own measurement facilities and capabilities. Included are cooperative measurement programs. A customer actually participates directly in the measurement of his device in order to become familiar with the measurement methods and assist in the analysis of the results. This is a useful approach when one is attempting to establish a new measurement capability that is related to or based upon NIST measurement techniques.

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References-Microwave Antenna Parameter Measurements

A Certification Plan for a Planar Near-Field Range Used for High-Performance Phased-Array Testing, M. H. Francis, A. G. Repjar, and D. P. Kremer, NIST Internal Report 3991 (July 1992).

Improvements in Polarization Measurements of Circularly Polarized Probes, A. C. Newell, D. P. Kremer, J. R. Guerrieri, Proceedings of the Antenna Measurement Techniques Association, pp. 1-30 through 1-35 (October 1989).

Calibrating Antenna Standards Using CW and Pulsed-CW Measurements and the Planar Near-Field Method, D. P. Kremer and A. G. Repjar, Proceedings, Antenna Meas. and Techniques Assoc., pp. 13-21 through 13-29 (September 1988).

Effect of Random Errors in Planar Near-Field Measurement, A. C. Newell and C. F. Stubenrauch, IEEE Trans. Antennas and Propagation, Special Issue on Near-Field Scanning, 36 (6), 769-773 (June 1988).

Accurate Determination of Planar Near–Field Correction Parameters for Linearly Polarized Probes, A. G. Repjar, A. C. Newell, and M. H. Francis, IEEE Trans. Antennas and Propagation, Special Issue on Near-Field Scanning, 36 (6), 855-868 (June 1988).

Improved Polarization Measurements Using a Modified Three-Antenna Technique, IEEE Trans. Antennas and Propagation, Special Issue on Near-Field Scanning, 36 (6), 852-854 (June 1988).

Gain and Power Parameter Measurements Using Planar Near-Field Techniques, A. C. Newell, R. Ward, and E. McFarlane, IEEE Trans. Antennas and Propagation, Special Issue on Near-Field Scanning, 36 (6), 792-803 (June 1988).

Error Analysis Techniques for Planar Near-Field Measurements, A. C. Newell, IEEE Trans. Antennas and Propagation, 36, 754-768 (June 1988).

Extrapolation Range Measurements for Determining Antenna Gain and Polarization, A. G. Repjar, A. C. Newell, and D. T. Tamura, NBS Tech. Note 1311 (August 1987).

The Determination of Near-Field Correction Parameters for Circularly Polarized Probes, A. C. Newell, M. H. Francis, D. P. Kremer, Proceedings Antenna Measurement Techniques Assoc. , pp. 3A3-1 through 3A3-29 (October 1984).

A Method of Determining the Mismatch Correction in Microwave Power Measurements, G. Engen, IEEE Trans. Instrum. Meas. IM-17, 4 (Dec. 1968).

Bolometric Microwave Power Calibration Techniques at the National Bureau of Standards, R. F. Desch and R. E. Larson, IEEE Trans. Instrum. Meas. IM-12, 1 (June 1963).

A Bolometer Mount Efficiency Measurement Technique, G. Engen, J. Res. Natl. Bur. Stand. (U. S.), 65C, 113 (Apr. -June 1961).

A Transfer Instrument for the Intercomparison of Microwave Power Meters, G. Engen, IRE Trans. Instrum. Meas. 19, 202 (Sept. 1960).

A Refined X-Band Microwave Microcalorimeter, G. Engen, J. Res. Natl. Bur. Stand. (U.S.), 63C, 77 (1959).

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Field Strength Parameter Measurements

Rate our Services

Technical Contacts:
Dennis G. Camell
Tel: 303-497-3214
E-mail: camell@boulder.nist.gov

Perry F. Wilson
Tel: 303-497-3406
E-mail: pfw@boulder.nist.gov

John Lomax
Administration and Logistics
Tel: 303-497-3842
Fax: 303-497-4286
E-mail: john.lomax@nist.gov

Please contact the administration and logistics staff before shipping instruments or standards to the address listed below.

Mailing Address:
National Institute of Standards and Technology
M.C. 818.02
325 Broadway
Boulder, CO 80305-3328

Service ID
Number
Description of Services Fee($)
64100S Special Test Services for Antenna/Field Strength/Measurement, Using the Transverse Electromagnetic (TEM)Cell Method (10 kHz to 300 MHz) At Cost
64300S Special Test Services for Antenna/Field Strength/Reflectivity Measurements, Utilizing the Anechoic Chamber and Standard Field Method At Cost
Fees are subject to change without notice.

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Special-Test Service for Antennas/Field Strength Measurements, Utilizing the Transverse Electromagnetic (TEM) Cell Method (64100S)

Standard electromagnetic fields are generated in TEM cells and used to calibrate electrically small antennas and antenna systems used for electromagnetic field probes in the frequency range 10 kHz to 300 MHz.

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Special-Test Service for Antennas/Field Strength Measurements, Utilizing the Anechoic Chamber and Standard Field Method (64300S)

A. Open-end waveguides (200 MHz to 450 MHz) are used to generate standard electromagnetic fields for calibrating antennas and electromagnetic field probes.

B. Pyramidal horns (0.45 GHz to 40 GHz) are used to generate standard electromagnetic fields for calibrating antennas and electromagnetic field probes.

Table 9.19 summarizes the field parameters, frequency ranges, and radiating antenna sources for the various NIST field strength measurement facilities.

Table 9.19. Summary of NIST Standard Field Strength Facilities

Field Parameter Type of Measurement Facility Frequency Range Radiating Antenna Source
H Wood building 14 kHz to 50 MHz Loop (20 cm)
E (vertical) Open Area Test Site (ground screen) 30 kHz to 30 MHz Short monopole
E (vertical) Open Area Test Site (ground screen) 30 kHz to 30 MHz Quarter wavelength monopole
E (horizontal) Open Area Test Site (ground screen) 30 MHz to 300 MHz Dipole, log-periodic antenna, etc.
E and H TEM cell 25 MHz to 1000 MHz  
Power Density Anechoic chamber 200 MHz to 450 MHz Open-end waveguide
Power Density Anechoic chamber 0.45 GHz to 46 GHz Pyramidal horn

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References-Electromagnetic Field Strength Parameter Measurements

Methodology for Standard Electromagnetic Field Measurements, N. S. Nahman, M. Kanda, E. B. Larsen, and M. L. Crawford, IEEE Trans. Instrum. Meas. IM-34, 4 (Dec. 1985).

A Review of Electromagnetic Compatibility/Interference Measurement Methodologies, M. T. Ma, M. Kanda, M. L. Crawford, and E. B. Larsen, Proc. IEEE, 73, 3, 388 (Mar. 1985).

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Program questions: Calibrations
Phone: 301-975-5454, Fax: 301-975-2950
NIST, 100 Bureau Drive, Stop 8363, Gaithersburg, MD 20899-8363