Field Strength and RFI Standards at the National Bureau of Standards

Abstract

Some of the calibration services offered to industry and other governmental agencies by the National Bureau of Standard's Radio Standards Laboratory are discussed. The emphasis is placed on field strength measurements and related calibration services at frequencies from 30 Hz to 12 GHz. These include the calibration of 3 basic types of antennas: (1) Loop antennas, (2) Half-wave dipole antennas and (3) Horn antennas. Methods of calibrating these antennas are described and illustrated. A discussion of calibration problems at microwave frequencies emphasizes the measurement errors as related to the antenna and receiver voltage standing wave ratios (VSWR). Antenna and receiver VSWR's are exemplified, and corresponding measurement errors are shown. Methods of estimating errors are given. The National Bureau of Standards recently designed and constructed some antenna standards for both the Air Force and the Navy. These standards were designed to calibrate loop and half-wave dipole antennas. The frequency range is 10 kHz to 1000 MHz. These antenna standards are briefly described and illustrated. The future plans for the development of antenna standards and broadband EMC standards at the National Bureau of Standards are discussed. Work is in progress in areas of impulse generators, random noise generators, and other instruments.