Active metasurface for broadband radiation and integrated low radar cross section

Abstract

In this paper, a novel design method that integrates broadband agile radiation and controllable scattering performance in one surface is proposed for an active metasurface. Each unit cell of the metasurface is incorporated with tunable devices, such as an electronic or micro-electro-mechanical-system (MEMS) varactor, to obtain frequency or spatial electromagnetic (EM) wave modulation. Besides, a probe is also adopted in the metasurface element so that the element can function as an antenna once fed by a transmitter. In this way, integrated broadband radiation and low radar cross section (RCS) are achieved for this type of active metasurface antenna (AMSA). To illustrate this method, an AMSA with a simple patch structure and lumped varactors, as an example, is demonstrated both numerically and experimentally. The results show that scanning radiation beams are obtained across a broad frequency band. Meanwhile, broadband flexible scattering performance is also realized by tuning the embedded varactors. Thus, a broad working band, reconfigurable radiation pattern, and low RCS are attained simultaneously for the AMSA. Good agreements between simulations and measurements further prove the effectiveness of the proposed method, which may have potential applications in stealth devices. Moreover, this method and the design strategy can be easily extended to other frequency range.