Ku 대역 저손실 소형 4×4 버틀러 매트릭스의 구현

Abstract

The Ku-band (12~18 GHz) is mainly used for long-range satellite communications and radar applications. Because the signal power is weak in a long-range communication, it is important to reduce the loss of the transmitter and receiver. In this paper, we propose a low-loss compact 4×4 Butler matrix structure that operates in the range of 15.7~16.7 GHz. To achieve low-loss characteristics, a low-loss transmission line was designed based on the suspended transmission line. To miniaturize the structure, the internal circuit of the Butler matrix was designed as a 100 Ω system, and the input/output stage was matched at 50 Ω. The size of the Butler matrix circuit manufactured through the optimized design was 45×22×2.3 mm. The insertion loss, isolation between terminals, and return loss of each terminal measured within the operating frequency band were 1.36 dB (including connector loss), 20.5 dB, and 15.3 dB, respectively, demonstrating a performance similar to that of the simulated performance. The proposed 4×4 Butler matrix can be utilized as a low-loss beam-switching circuit for a 1×4 linear array antenna.