Title: Multi-Channel Correlator Array-Fed Microwave Radiometer
Presenting Author: Jeffrey Piepmeier
Organization: NASA Goddard Space Flight Center
Co-Author(s): Giovanni De Amici, Thomas Holmes, Jared Jordan, Ali Mahnad, Jinzheng Peng, Paul Racette, Rafael Rincon, Ken Vanhille

Abstract:
New antenna feed technology is needed for microwave radiometers as aperture sizes continue to increase. Capability for contiguous coverage and spatial Nyquist sampling can be achieved using a multi-beam array-fed reflector architecture adapted from radio astronomy. In this ACT, a wideband feed array for use in a multi-channel (X-W bands) scanning microwave radiometer is in development. The team, including array provider Nuvotronics Inc., is also developing a laboratory instrument to demonstrate the performance of the array-fed architecture at 36.5 GHz using an 80-cm projected aperture. The feed array is an 11-element line array based on a microfabricated 8-40 GHz feed. Multiple beams are generated by exciting overlapping groups of elements with each group shifted by one element spacing within the array. The modeled antenna patterns reveal six beams with 0.8-degree beamwidth and 0.3-degree spacing. This configuration is also a 1:26 electromagnetic scale model of a 1.41 GHz radiometer with 21-meter aperture. The array-fed architecture for microwave radiometers has the potential to solve the developing need for high-spatial resolution, large aperture instruments. The objective relevancy scenario is a 6-meter aperture X-W band scanning radiometer purposed for high-resolution all-weather imaging of Earth's atmosphere and land, ice and ocean surfaces. This project entered at TRL 2 with an architecture concept and preliminary simulations of antenna performance. The team will mature the technology during a two-year period of performance (Feb. 2018-Feb. 2020) exiting at TRL 3.