Perforated Multilayer Ultrawideband Absorber Based on Circuit Analog Absorber With Optimal Air Spaces

A multilayer ultrawideband circuit analog absorber is proposed in this letter. The absorber comprises three layers: two absorbing layers and a metal ground layer. With the whole profile unchanged, the effects of the air spaces between absorbing layers on bandwidth enhancement are mainly addressed. The equivalent circuit is employed to analyze the appearance of reflection maximum poles, which limit the absorption at high frequencies. Based on the optimal equivalent circuit, two single-polarization perforated absorbing layers consisting of interdigital capacitors, meander lines, and lumped resistors are designed to achieve an ultrawide absorption band. For demonstration, a multilayer absorber is manufactured to validate the approach, where a bandwidth ratio of 1: 12.88 with a total profile of 0.101λ
_L
at the lowest operating frequency is achieved under normal incidence. The simulated results are experimentally verified by the measured results.