Dual-Band Submillimeter-Wave Leaky-Wave Lens Antenna for Heterodyne Cometary Mapping

The next generation of space-based submillimeter-wave remote cometary mapping instruments is being developed at NASA/JPL with two receiver bands at 210–240 GHz and 500–580 GHz. This instrument requires an array of receivers to decrease image acquisition time of velocity-resolved maps of key cometary volatiles. Furthermore, a single shared focal plane is required to save power, mass and space while maintaining overlapping and equal-beamwidth target illumination at both bands. Here, we describe the analysis, synthesis, fabrication and measurement of a prototype dual-band, submillimeter-wave leaky-wave lens antenna intended for a 4×4 focal-plane array (FPA) under a parabolic reflector that achieves these goals. The FPA elements are waveguide-fed leaky-wave lens antennas with a novel stratification including an integrated frequency-selective surface (FSS) that enables 15% operational bandwidths around 225 GHz and 540 GHz simultaneously. The propagating leaky-wave modes in this stratification are studied in detail and the stratification is then synthesized in manufacturable components. A submillimeter-wave lens antenna prototype was fabricated using high-precision silicon microfabrication techniques. Measurements of this prototype demonstrates a performance closely matching simulated results in both frequency bands.