2-D Epsilon-Near-Zero (ENZ) Feeding Network for High-Gain Millimeter-Wave Slot Antenna Array Using Bulk Silicon MEMS Technology

In this article, a high-gain millimeter-wave (mmW) slot antenna array is proposed based on a novel two-dimensional (2-D) epsilon-near-zero (ENZ) feeding network. This ENZ feeding network includes two stages of ENZ cavities, in which the in-phase ENZ mode is constructed with a stair-like amplitude distribution for electric field, which is achieved using a waveguide at its cutoff frequency. It is vital to highlight that the compact construction of the 2-D ENZ feeding network decreases the overall path length during signal transmission. To eliminate the dielectric loss inside the ENZ cavity, the bulk silicon microelectromechanical systems (MEMS) micromachining technology is used to fabricate hollow air-filled waveguide for high radiation efficiency. In this way, a high-aperture-efficiency 2-D slot antenna array is fabricated at mmW band, with the experimental results demonstrating an impedance bandwidth of 63–63.7 GHz, a peak gain of 21.8 dBi, and a total efficiency of 95.4%, rendering it a potentially asset for integration into point-to-point wireless systems.