Uplink Array Demonstration with Ground-Based Calibration

of Technology. Government sponsorship acknowledged. A set of small, separately steerable reflector antennas has been used as a transmitting phased array for the purpose of demonstrating techniques that can be used in a larger array to serve the future uplink transmission needs of NASA’s Deep Space Network. We envision an opera-tional array with 100 or more antennas that could generate the order of 1 TW of effective isotropic radiated power (EIRP). The demonstration is a small-scale version of this with five antennas and about 1 MW of EIRP. Each antenna has a 1.2-m-diameter aperture and a 2-W power amplifier, and the array operates in the 14.0- to 14.5-GHz communication satellite band. The main technical challenge for an uplink array is to ensure that the carrier phases of the signals from all antenna elements are aligned when the signals arrive at the receiver on a distant spacecraft. This requires a method of phase calibration. In the demonstration, we have shown that active receivers attached to the Earth near the array can be used as cali-bration targets. Measurements made at these receivers have been successfully used to calcu-late the phase adjustment needed at each antenna to achieve the desired alignment, even though the destination spacecraft is in a direction and at a distance very different from tha