Radio Frequency Fields Group Antenna Measurement Theory and Application Project  Leaders:  Michael H. Francis Katie MacReynolds Summary: NIST has shown that the near-field methods, which it invented for antenna characterization, offer capabilities in accuracy that are unsurpassed by other methods. However, developments are needed for advanced antenna for higher frequencies. Accordingly, NIST will develop near-field theory, standards, and methods to support characterization of gain, pattern, and polarization of advanced antennas at frequencies to 500 GHz. Background: Manufacturers of antennas and microwave systems incorporating antennas need practical, rapid, and efficient methods of characterizing antenna performance. Operation at higher frequencies, the use of advanced phased arrays for steering beams, the use of conformal structures in aircraft, and the use of active arrays challenge existing methods. Such systems support national goals for information highways and personal communications, and new radars for air traffic control to make more efficient use of air space without jeopardizing public safety. Advanced civilian systems include new generations of communications systems at higher frequencies and with greater spatial discrimination to alleviate overcrowding of current and synchronous-orbit satellites. Goals: Goals include (1) achieving uncertainties of less than 0.2 dB in the gain, (2) implementing probe-position error correction for mm-wave measurements, (3) determining field uniformity using spherical near-field uniformity for antenna measurement range characterization, and (4) developing and testing adaptive phased-array diagnostic methods. Current Tasks: Near-Field Antenna Calibrations Develop planar near-field metrology for measuring microwave antennas operating at frequencies up to 500 GHz. Develop new metrology methods for rapid microwave antenna measurements and diagnostics. Develop non-planar near-field measurements for antenna and probe measurements. Develop metrology for complex antennas for emerging technologies. Provide technology transfer through courses.  Facilities: Include a 3.5 m X 3.5 planar near-field range, a 2.5 m X 2.5 m planar near-field range, a 7 m long extrapolation, and a multipurpose range capable of spherical and cylindrical near-field measurements as well as probe far-field pattern measurements.