Title: A Novel Dual-Band Reflector/Reflect Array Antenna; An Enabling Technology for NASA’s ACE Radar
Author: Paul Racette
Organization: NASA Goddard Space Flight Center
Co-Authors: Gerald Heymsfield, Lihua Li, Michael Cooley, Richard Park, Peter Stenger

Abstract:
NASA’s Earth Science Decadal Survey calls for an Aerosol, Cloud and Ecosystems (ACE) mission for measurements to provide a better understanding of the role of aerosols on cloud development. The ACE Science Working Group recommends a dual-frequency satellite-based radar comprised of a fixed beam 94 GHz (W-band) radar and a wide-swath 35 GHz (Ka-band) imaging radar. This paper describes a novel dual-frequency shared aperture Ka/W-band antenna design that enables wide-swath imaging via electronic scanning at Ka-band and is specifically applicable to ACE. The innovative design minimizes size and weight via use of a shared aperture and builds upon NASAís investments in large-aperture reflectors and W-band radar architectures.

The dual-frequency antenna design is comprised of a primary cylindrical reflector/reflectarray surface illuminated by a fixed W-band feed (compatible with a quasi-optical beam waveguide feed, such as that employed on NASAís CloudSat) and a Ka-band Active Electronically Scanned Array (AESA) line feed. The highly innovative reflectarray surface provides beam focusing at W-band, but is transparent at Ka-band.

Under a newly awarded IIP, NASA Goddard Space Flight Center (GSFC) and Northrop Grumman Electronic Systems (NGES) are working on an antenna system design and a detailed risk reduction design effort leading to demonstrations of key components of the dual-frequency antenna system. We are designing, building and demonstrating a scale model of the dual-frequency reflector/reflectarray antenna. In addition, we are developing detailed designs of the Ka-band AESA line feed and the associated T/R module and will demonstrate key T/R MMIC technologies.