Novel AESA Architecture for Earth Observation and Planetary Sciences

In this paper we present a description and evaluation of Gallium Nitride (GaN) Transceivers within AESA frontends for space-based Synthetic-aperture radar (SAR). The GaN power switches are evaluated in a voltage mode Class-D (VMCD) RF amplifier and as a DC-DC converter. The efficiency of the circuit when evaluated as a Class D power amplifier (PA) is 73% at 250 MHz and delivers an output power of 37.3 dBm. The measured DC-DC converter circuit has an efficiency of over 89.7% at 100 MHz, delivering 38.6 dBm. These are the highest reported efficiencies for the RF PA and the switching modulator performance is comparable to state of the art at its respective operating frequencies. A flat panel metasurface antenna topology that can be integrated into the RF front end to facilitate a variety of SAR modalities. This antenna structure can substantially simplify the deployment mechanism of airborne and spaceborne SAR instruments.