Design and Development of a 2-D Electronically Scanned, Dual-polarization, Line Replaceable Unit (LRU) for Airborne Phased Array Radar for Atmospheric Research

A modular, dual-polarized, two-dimensional electronically scanned, C-band phased array radar is currently under consideration by The National Center for Atmospheric Research (NCAR) for the next generation of airborne radar for meteorological research. NCAR's Earth Observing Laboratory (EOL) is conducting a 2-year project to develop a small, prototype array that will be used as proof of concept for this future airborne radar. The antenna array is a flat tile panel, representing one Line Replacement Unit (LRU). In total, 56 LRU's will be needed to populate the full airborne phased array antenna. The LRU consists of 64 elements (8x8). Each element is placed in a square grid, where separation between elements is half a wavelength. The size of the LRU was chosen based on cost-performance modeling and reliability analysis. Each radiating antenna element is excited with a Transmit Receive (TR) module that operates in Alternate Transmit and Simultaneous Receive (ATSR) polarization mode. The TR module is a customized development by Massachusetts Institute of Technology's Lincoln Laboratory (MIT/LL) and M/A-COM Technology Solutions (MTS).

A new radiating antenna element will be presented. The antenna was carefully designed in a multilayer structure that satisfies the cost and polarization requirements for the dual-polarized airborne radar. Better than -20 dB cross-polarization isolation and an antenna pattern mismatch below 7% is obtained over a scanning range of ± 45 degrees and in the principal and diagonal planes (E, H and D).

This paper outlines and describes design and performance of the LRU antenna and its components. It provides preliminary test results of the antenna radiating element. Emphasis will be place on the scanning performance, scanning impedance, ripples, co-polar mismatch and cross-polarization isolation.