Research Article

Design of composite right/left-handed transmission line for phase shifter of multi-band base station antenna

¹ Department of Electrical and Electronic Engineering, National Defense Academy, Yokosuka 239-8686, Japan
² Department of Electronic Systems Engineering, Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100 Kuala Lumpur, Malaysia
³ Department of Information and Communication Systems Engineering, Chiba Institute of Technology, Narashino 275-0016, Japan

^* e-mail: naobumi@nda.ac.jp

Received: 3 September 2018
Accepted: 17 November 2018
Published online: 19 December 2018

Abstract

In multi-band base station antennas, interference toward neighboring cells at low operating frequency in-creases since tilting angle is frequency-independent and beamwidth in the vertical plane increases as de-creasing the operating frequency. In this paper, the realization of the different phase shifts at each frequency is proposed by using the dispersion relation of the composite right/left-handed transmission line. The feasi-bility of the phase shift is clarified by using equivalent circuit model of the unit cell. Next, the dispersion and Bloch impedance of the actual configuration of the unit cell are designed. The inverse phase shift at each frequency is verified experimentally.