Miniaturised frequency selective surface‐based rasorber with wideband two‐sided absorption and switchable transmission/reflection band

Abstract

Abstract A new rasorber with a switchable transmission/reflection band between two wide absorption bands is proposed based on an ultrathin low‐profile frequency selective surface. To miniaturise the periodicity in the lossy layer, convoluted elements and lumped capacitors are applied, while in the bandpass layer, non‐resonate elements are implemented with PIN diodes embedded. Moreover, a square loop loaded with resistors is introduced to the bottom of the lossy layer, which consequently extends the bandwidth of the high‐frequency absorption band without an increase in thickness. The simulation indicates that the proposed design presents a switchable transmission/reflection band in two‐sided absorption bands with a periodicity of 0.089λL (wavelength at the lowest operating frequency) and thickness of 0.066λL. Angular stability and polarisation insensitivity are also obtained due to the low profile and symmetry. A prototype was fabricated and measured, according to which the switchable transmission band covers 3.67–3.93 GHz; the absorption bands cover 2.37–3.23 GHz and 4.09–6.63 GHz in the OFF state of the diodes, and 2.23–3.02 GHz and 4.01–6.53 GHz in the ON state. As reasonable agreements between the measurement and simulation results are observed, the performance of the design is verified.

Keywords

• active filters
• diodes
• frequency selective surfaces
• radar absorbing materials