This paper introduces a novel, compact broadband beam steering array antenna leveraging a Butler matrix feed network. Addressing the challenges of short-range mm-wave propagation, we propose a dual-pronged approach: broadside single-antenna elements and a Butler matrix-based feed network. The single elements, compact zeroth-order resonance antennas, are efficiently fed via the aperture technique. To further enhance performance, we explore the integration of metamaterial mushroom structures, enabling low-distance operation and reduced mutual coupling. These structures can effectively manipulate electromagnetic waves, minimizing signal interference between adjacent antenna elements.

The proposed 16-element (4x4) array, with 0.35𝜆 inter-element spacing, achieves a broadband impedance bandwidth of 32-38 GHz and a wide scan angle of approximately 93°. This innovative design aims to deliver a high-gain, broadside beam steering antenna, crucial for applications requiring precise beam directionality and efficient signal transmission in the mm-wave band.

The paper presents a detailed, step-by-step process, including simulations and measurements, to realize this novel antenna. This comprehensive approach encompasses the design, optimization, and characterization of the antenna array, providing valuable insights into its performance and potential applications