Reconfigurable Mushroom-Based Metasurface Antenna for Continuous Beam Steering

We present the design and numerical validation of a reconfigurable metasurface (MTS)-based leaky wave antenna (LWA) that achieves continuous angular scanning through broad-side at a fixed frequency in the millimeter-wave (mmWave) range. The proposed LWA uses a mushroom structure integrated with voltage-controlled varactors to achieve tunability. The mushroom configuration is chosen to ease the accommodation of biasing lines, which can be cumbersome at mmWave frequencies. The desired radiation pattern and suppression of the open stopband (OSB) at broadside, essential for achieving continuous beam scanning, are achieved through a proper design of the impedance modulation. Since this approach relies on a precise modeling of the equivalent impedance, we investigate two types of impedance boundary condition (IBC) models -opaque and transparent - to evaluate how accurately they can capture the electromagnetic behavior of the mushroom structure. Extensive full-wave simulations are conducted to assess the performance of these models in predicting leaky-wave properties. Based on the insights provided by this study, a reconfigurable LWA is designed and numerically analyzed, demonstrating continuous beam scanning and effective OSB suppression. The results highlight the potential of impedance-based design techniques and provide valuable insights for advancing high-performance reconfigurable antennas in mmWave systems.