Dr. John D. Norgard Profile

Dr. John D. Norgard

Chair MAE at Univ of Colorado at Colorado Springs

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Author

Publications (10)

Proceedings Article | 1 April 2003 Paper

Direct infrared measurements of phased-array antenna source distributions

John Norgard, Randall Musselman

Proceedings Volume 5073, (2003) https://doi.org/10.1117/12.496903

KEYWORDS: Antennas, Thermography, Phased arrays, Infrared cameras, Near field, Cameras, Sensors, Infrared radiation, Infrared detectors, Calibration

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A thermal imaging technique has been developed to measure electromagnetic (EM) fields. This technique is applied in this paper to measure the EM fields radiated by phased array antennas. This thermal technique is based on infrared (IR) measurements of the heat patterns produced in a thin, lossy detector screen placed near the antenna in the plane over which the field is to be measured. A low-loss, planar detector screen was made from a carbon loaded polyimide film to measure the intensity distribution of the electric field radiated from the antenna. The Joule (conductive) heating in the screen causes the temperature of the screen to rise in proportion to the intensity of the wave incident on the screen. The temperature distribution on the surface of the film is captured with an IR imaging camera. The magnitude of the radiated field at each location in the detector screen (on a pixel by pixel basis) is determined directly from the temperature distribution in the IR thermogram of the field. The temperature rise in the screen material (over the ambient background temperature of the screen) was measured at NIST/Boulder when the screen was irradiated by a plane wave of known intensity. A calibration table of measured temperature rise versus expected field intensity was obtained for the detector screen. This thermal imaging technique has the advantages of simplicity, speed, and portability over existing hard-wired probe methods and produces a 2D picture (a pseudo-color image) of the field. In general, these images can be used for field diagnostics of the antenna (near-field or far-field patterns) and/or to evaluate the aperture excitation of the array. In particular, the source distribution in the aperture plane of the antenna was measured. This distribution can be compared to a standard 'test pattern', e.g., full power, equal-phase, broadside illumination, to determine the operational state of each individual element of the array, which controls the radiation pattern of the antenna. Phase shifters and/or attenuators which produce incorrect element phase magnitudes or phase shifts can be identified with this technique. Faulty elements, once located, can be repaired.

Proceedings Article | 18 October 2001 Paper

Dielectric oblate spheroidal model of buried landmines

Scott Gruber, John Norgard

Proceedings Volume 4394, (2001) https://doi.org/10.1117/12.445460

KEYWORDS: Mining, Optical spheres, Land mines, Dielectrics, Scattering, Chemical elements, Bessel functions, Radon, Applied sciences, Backscatter

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Proceedings Article | 4 April 1997 Paper

Phaseless measurements of antenna near fields from infrared images using holographic phase retrieval

John Will, John Norgard, Michael Seifert

Proceedings Volume 3056, (1997) https://doi.org/10.1117/12.271651

KEYWORDS: Antennas, Holograms, Near field, Holography, Phase measurement, Infrared imaging, Near field optics, Optical simulations, Microwave radiation, Infrared radiation

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Proceedings Article | 15 March 1996 Paper

Phase measurements of electromagnetic fields using infrared imaging techniques and microwave holography

John Will, John Norgard, Carl Stubenrauch, Katie MacReynolds, Michael Seifert, Ronald Sega

Proceedings Volume 2766, (1996) https://doi.org/10.1117/12.235388

KEYWORDS: Antennas, Near field, Cameras, Phase measurement, Infrared imaging, Thermography, Holography, Microwave radiation, Temperature metrology, Phase retrieval

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Proceedings Article | 28 March 1995 Paper

Empirical calibration of infrared images of electromagnetic fields

John Norgard, Michael Seifert, Ronald Sega, Anthony Pesta

Proceedings Volume 2473, (1995) https://doi.org/10.1117/12.204871

KEYWORDS: Thermography, Sensors, Calibration, Antennas, Magnetism, Infrared radiation, Electromagnetism, Infrared imaging, Polarization, Electric field sensors

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Proceedings Article | 21 March 1994 Paper

Infrared measurements of waveguide modes and radiation patterns of beveled-cut circular waveguide microwave aperture antennas

John Norgard, Joseph Sadler, Ronald Sega, Ernest Baca, William Prather

Proceedings Volume 2245, (1994) https://doi.org/10.1117/12.171179

KEYWORDS: Waveguides, Antennas, Microwave radiation, Infrared imaging, Sensors, Thermography, Infrared radiation, Infrared cameras, Waveguide modes, Cameras

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SPIE Journal Paper | 1 January 1994

Infrared/microwave correlation measurements

John Norgard

OE, Vol. 33, Issue 01, (January 1994) https://doi.org/10.1117/12.10.1117/12.155377

KEYWORDS: Sensors, Magnetism, Thermography, Waveguides, Antennas, Cameras, Infrared cameras, Microwave radiation, Magnetic sensors, Infrared imaging

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Proceedings Article | 6 April 1993 Paper

Thermal images of magnetic fields near conductive surfaces

Amir Matini Kashini, John Norgard, Ronald Sega, Bob Ayres, Michael Harrison, Richard Komar, Hugh Pohle, William Prather, Mark Smith

Proceedings Volume 1933, (1993) https://doi.org/10.1117/12.141979

KEYWORDS: Magnetism, Microwave radiation, Epoxies, Thermography, Nickel, Zinc, Infrared cameras, Antennas, Copper, Magnetic sensors

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Proceedings Article | 1 April 1992 Paper

Infrared detection of free-field and cavity perturbations of electromagnetic probe measurements

John Norgard, Ronald Sega, Michael Seifert, John Cleary, Michael Harrison

Proceedings Volume 1682, (1992) https://doi.org/10.1117/12.58545

KEYWORDS: Sensors, Electromagnetism, Optical spheres, Magnetism, Free space, Thermography, Polarization, Infrared cameras, Cameras, Infrared detection

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Proceedings Article | 1 December 1991 Paper

Infrared/microwave correlation measurements

John Norgard, Don Metzger, John Cleary, Michael Seifert

Proceedings Volume 1540, (1991) https://doi.org/10.1117/12.48776

KEYWORDS: Microwave radiation, Thermography, Infrared imaging, Infrared radiation, Electromagnetism, Infrared technology, Infrared detection, 3D metrology, Calibration, Scattering

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