Design of low-profile broadband capacitive circuit absorber
A low-profile broadband capacitive circuit absorber has been demonstrated both numerically and experimentally. The design consists of square loop resonators and lumped resistors periodically arranged on the top of grounded dielectric substrate. The novelty of the design lies in its capacitive reactance due to square loop geometry, which reduces the electrical thickness of the structure compared with the earlier broadband absorbers. The simulated results show that the structure exhibits reflectance below −10 dB from 1.91 to 5.75 GHz with the thickness of only 0.07λl at the lowest operating frequency. Furthermore, the proposed structure is polarisation insensitive as well as angularly stable. The structure has also been fabricated, whose measured result is in good agreement with the simulated response.