An ultra‐wideband 3 × 3 Butler matrix with unique Vivaldi array structure for high‐range resolution radars

Abstract

Steerable antenna beam capability is an outstanding expectation for the development of automatic tracking systems and target detection. A switched beam array antenna, which can generate multiple fixed beams with enhanced sensitivity, emerges as a solution for beamforming tracking. On the other hand, it is known that the target can be detected with high-range resolution thanks to ultra-wideband (UWB) systems. In this work, a compact switched beam Vivaldi array antenna based on a Butler matrix for a UWB application capable of target detection with accurate target tracking is presented to meet the high gain and low side lobe level requirements. Based on a three-element antenna array, two methods have been applied to obtain small grating lobes and it has been shown that significant improvements can be achieved. Designed with a 3 Â 3 UWB Butler matrix, the UWB array antenna can direct its beams in three directions in a direction range from À42 to 42 . The measured result showed that the group delay was less than about 4.5 ns with variation of less than ±0.7 ns over the entire operating frequency band.

A review of microwave electronically scanned array: Concepts and applications

“…15 For conventional phased arrays, phase shifters are key components to tune the phase to realize electronic scanning, but they are still the most complex and expensive parts of systems. There have been some alternatives to phase shifters to achieve phase changes in the array, such as passive beamforming network, 16 series-fed arrays, 17 steerable parasitic arrays, and so forth. Another array that use phase changes for beam scanning is the focused aperture array, with reflectarray 14 and transmitarray 18 being the two main types.…”