MetaBeam: A high-gain pencil-beam array antenna based on corporately fed CRLH meta-lines for the 24 GHz ISM band

One of the objectives in the “MetaBeam” research project was the development of a high-gain pencil-beam array antenna based on composite right/left-handed (CRLH) metamaterial transmission-lines, shortly referred to as CRLH meta-lines. This paper presents an initial prototype for this work-package. We aimed for applications within the 24 GHz ISM band, like automotive radar systems, where low-cost is a major concern. Therefore, the antennas have been realized with a standard multi-layer printed circuit board technology based on Rogers RO4350/4450 laminates, which are approved for automotive applications. The antenna with a two-dimensional aperture is essentially based on corporately fed one-dimensional CRLH meta-lines, which have an electrically long extent and operate therefore as leaky-wave antennas (LWAs) in the fast-wave regime. A conventional corporate feeding network based on Wilkinson power dividers is used to uniformly distribute the power to the different columns. Here, the results of an eight-column array antenna, where each meta-line is composed of 20 unit cells are presented. The overall dimensions are 44 mm (8 times a pitch of 5.5 mm) by 45 mm (20 times the period of 2.25 mm), which roughly corresponds to an electrical size of (4 λ₀)², and a gain of 17.4 dB at 24.5 GHz has been measured.