Broadband calculable dipole reference antennas

A broadband calculable standard dipole antenna has been developed, with an uncertainty in the antenna factor (AF) of better than /spl plusmn/0.15 dB at the resonant frequency, f/sub res/, in the frequency range 30 to 500 MHz and /spl plusmn/0.2 dB in the range 600 MHz to 1 GHz. For broadband operation of the dipole resonant at 60 MHz the uncertainty is /spl plusmn/0.2 dB over a range 0.33 f/sub res/ to 1.83 f/sub res/. These uncertainties have been validated by close agreement of the measured insertion loss between dipole antennas above a conducting ground plane, with the loss predicted by analytical and numerical methods. The AF measured by the two-antenna method also agrees with the calculated AF. The technique was applied to reference monopole antennas for which AF was determined to an uncertainty of /spl plusmn/0.2 dB over the frequency range 10-100 MHz. The key achievements are: the construction of a very large and flat ground plane, validation of numerical versus analytical calculations of impedance and effective length of resonant dipoles, excellent agreement between measurements and method-of-moments calculations of the coupling between resonant dipoles, good agreement over a broad bandwidth, careful design of antennas and supports, and precision measurements.