Citation
Abstract
Typical ground antennas intended for use in space communications require large apertures operating at high frequencies. The challenge involved with these applications is achieving the required antenna performance in terms of antenna aperture efficiency and pointing accuracy. The utilization of a focal-plane array in place of a standard single-mode feed minimizes these problems. This article discusses the key elements required to implement a focal-plane array on a large high-frequency antenna. The example of the NASA Deep Space Network 70-m antennas operating at 32 GHz has been chosen to illustrate these advantages. The design of a suitable feed and low-noise cryogenically cooled amplifier and the required signal-processing techniques are described. It is shown that adaptive least mean-square algorithms can be applied to the output of the array elements, in order to obtain the optimum combining weights in real time, even in the presence of dynamic interference (nearby spacecraft in the array’s field of view or planetary radiation). This adaptive optimization capability maximizes the combined output signal-to-noise ratio in real time, ensuring maximum data throughput in the communications link when operating in the presence of receiver noise and external interference generally present during planetary encounters.
Keywords
Details
- Volume
- 42-170
- Published
- August 15, 2007
- Pages
- 1–18
- File Size
- 387.2 KB