Low-Profile Epsilon-Near-Zero (ENZ) Cavity Antenna Array for Wide-Angle Beam Scanning

In this letter, a low-profile epsilon-near-zero (ENZ) cavity antenna array is proposed to achieve wide-angle beam scanning. The proposed array utilizes four slot-fed cavity antenna elements that operate with the ENZ mode, in which the electric field presents a unique sign-function-like distribution. By properly designing the width of the ENZ cavity, a wide 3 dB beamwidth is achieved in a low profile to increase the beam scanning angle of the array configuration. Furthermore, the narrow width of the antenna element also facilitates a decreased spacing between array elements, enabling the use of the appropriate spacing to increase the scanning angle. Different from the conventional wide-angle beam-scanning arrays with high profile, the proposed ENZ cavity antenna array achieves a remarkable beam scanning angle of ±72° (±73° in the measurement) while maintaining a low profile of only 0.03 λ
₀
, exhibiting the potential applications in low-profile phased array systems.