SPC has a growing program in performing ground and foliage penetration, primarily from airborne platforms. Currently, the platform being used is a UH-1 Huey helicopter, configured with a palletized MkV radar.
The initial configuration for this system used horizontal (H) and vertical (V) polarized log dipole antennas and step-chirped the transmit signal over the frequency range from 150 - 450 MHz. Some steps in the chirp were suppressed to make the radar conform to FCC frequency clearance requirements. Data were collected for SAR imaging in both HH and VV mode.
In this configuration, data at 1 m resolution were acquired over 10 square miles of terrain in Oklahoma. Data from this initial configuration were processed using both tomographic and range migration algorithms.
After completion of this first project, a number of adjustments were made to the system configuration. The most important of these changes was replacing the log periodic antennas with an array of crossed dipoles to improve the system gain and allow efficient collection of crossed-polarization data. Also, the mounting structure was re-designed to be carried beneath the skids and jettisoned in case of an emergency.