Low-Profile FSS-Based Polarization-Insensitive Rasorber With Switchable Transmission Band

In this letter, a new polarization-insensitive, low profile frequency-selective rasorber (FSR) is presented with a switchable transmission band. This FSR consists of a lossy layer, a bandpass layer, and a switchable layer where p-i-n diodes are mounted and parallel fed. The lossy layer is composed of compact fractal elements with lumped resistors, which miniaturizes the unit dimensions. The bandpass layer is composed of a grided square loop and the switchable layer is integrated by coaxial hybrid square loops with an embedded bias network, whose configuration reduces the impact of bias lines on high-frequency transmission and, consequently, achieves polarization insensitivity. A prototype was fabricated and measured, which verified that the 3 dB transmission window covers 8.9–9.8 GHz, and the −10 dB wideband absorption covers 2.3–8.2 GHz. Good agreement is obtained between the numerical simulation and measurement results.