Evolutionary Design of a Phased Array Antenna Element.pdf

Evolutionary Design of a Phased Array Antenna Element 1 2 3 Al Globus , Derek Linden , and Jason Lohn 1 University of California at Santa Cruz 2 JEM Engineering 3 NASA Ames Research Center Introduction We present an evolved S-band phased array antenna element design that meets the requirements of NASA’s TDRS-C communications satellite scheduled for launch early next decade. The original specification called for two types of elements, one for receive only and one for transmit/receive. We were able to evolve a single element design that meets both specifications thereby simplifying the antenna and reducing testing and integration costs. The highest performance antenna found using a genetic algorithm and stochastic hill-climbing has been fabricated and tested. Laboratory results are largely consistent with simulation. Researchers have been investigating evolutionary antenna design and optimization since the early 1990s (e.g, [1]), and the field has grown in recent years as computer speed has increased and electromagnetic simulators have improved. Many antenna types have been investigated, including wire antennas [2], antenna arrays [3], and quadrifilar helical antennas [4]. In particular, our laboratory evolved a wire antenna design for NASA’s Space Technology 5 (ST5) spacecraft. This antenna [5] has been fabricated, tested, and is scheduled for launch on the three spacecraft in 2006. TDRS-C Mission Requirements TDRS-C is designed to carry a number of antennas, including a 46 element phased array. Element spacing is triangular at approximately 2λ. Each element gain must be 15dBic on the boresight and 10dBic to θ