Dual-band shared aperture reflector/reflectarray antenna: Designs, technologies and demonstrations for nasa´s ACE radar

NASA´s planned Aerosol, Cloud and Ecosystems (ACE) mission will provide RF measurements for studying the role of aerosols on cloud development. The space-borne radar requires a fixed-beam at W-band and a wide-swath (>100 km) scanning beam at Ka-band. The full scale antenna is comprised of a parabolic cylinder reflector/reflectarray with a fixed W-band feed and a Ka-band Active Electronic Scanning Array (AESA) feed. Cassegrain folded optics is employed to reduce the required mass, volume, mechanical complexity and cost. An innovative reflectarray design provides a focused low-loss pencil beam at W-band, and is RF transparent at Ka-band. The AESA transmit/receive (T/R) modules provide high RF output power and low noise figure. Several planar reflector/reflectarray prototypes were designed and fabricated to validate the novel reflectarray element/surface technology and design methodology. The measured W/Ka band reflector/reflectarray gains and patterns agree very well with predictions thereby confirming the viability of the full scale design.