MILLIMETER-WAVE DOUBLE-DIPOLE ANTENNAS FOR HIGH-GAIN INTEGRATED REFLECTOR ILLUMINATION

A double-dipole antenna backed by a ground plane has been fabricated for submillimeter wavelengths. The double-dipole antenna is integrated on a thin dielectric membrane with a planar detector at its center. Measured feed patterns at 246 GHz agree well with theory and demonstrate a rotationally symmetric pattern with high coupling efficiency to Gaussian beams. The input impedance is around 50-OMEGA, and will match well to a Schottky diode or SIS detector. The double-dipole antenna served as the feed for a small machined parabolic reflector. The integrated reflector had a measured gain of 37 dB at 119-mu-m. This makes the double-dipole antenna ideally suited as a feed for high resolution tracking or for long focal length case-grain antenna systems.