In this letter, a broadband polarization-independent tunable absorber is proposed based on active frequency selective surface (AFSS). The AFSS consists of periodic patterns of four-patch array with four p-i-n diodes loaded among them, and a simple bias network is designed behind the ground plane through metalized via holes, which can effectively reduce the influence on the absorbing performance. By changing the bias voltage applied on the p-i-n diodes, the reflectivity of our absorber can be dynamically adjusted from near-unity reflection to less than −10 dB absorptivity under normal incidence over a wide frequency band ranging from 8.5 to 18.2 GHz. Due to the symmetrical structure of the AFSS, our absorber still has polarization insensitivity. We fabricated this AFSS absorber sample, and its measured results agree well with the simulated ones.

中文翻译：

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使用有源频率选择表面的宽带偏振不敏感可调谐吸收器

在这封信中，提出了一种基于有源频率选择表面 (AFSS) 的宽带偏振无关可调吸收器。AFSS由四片阵列的周期性图案组成，其中加载了四个pin二极管，并通过金属化过孔在地平面后面设计了一个简单的偏置网络，可以有效减少对吸收性能的影响。通过改变施加在 pin 二极管上的偏置电压，我们的吸收器的反射率可以在 8.5 至 18.2 GHz 的宽频带范围内，在垂直入射下从接近统一反射动态调整到小于 -10 dB 的吸收率。由于 AFSS 的对称结构，我们的吸收器仍然具有极化不敏感性。我们制作了这个 AFSS 吸收体样品，其测量结果与模拟结果非常吻合。