Dual dipole imaging array for MIR and ECE imaging

Two dual dipole antennas have been designed in the frequency range of 85-95 GHz and 100-135 GHz for use as imaging array elements for magnetic fusion plasma microwave imaging reflectometry (MIR) and electron cyclotron emission imaging (ECEI) diagnostics, respectively. The antenna pattern is of primary importance for these applications, with emphasis on clean antenna patterns and low sidelobe levels for low interchannel crosstalk, tight channel spacing to minimize interchannel spacing in the plasma, and wide instantaneous bandwidth for real time 2D imaging. The extremely high temperature of the imaged plasma (>10 million degrees), means that a low receiver noise temperature is not critical as long as it is sufficiently low (/spl les/20000 degrees) to facilitate absolute calibration. The simulated and measured antenna patterns are presented in this paper.