Active low frequency band expansion mechanism of electromagnetic wave absorber composite structure

Abstract Bandwidth expansion of modern antennas and communication systems raises growing demand for electromagnetic wave absorber in compatibility equipment. Single absorption mechanism is hard to reach well-balanced characteristics including wide bandwidth, low frequency absorption and small thickness. Based on the composite structure concept, composite structure for electromagnetic wave absorber’s active low frequency band expansion is proposed, by combining circuit-analog absorber and active absorber to form a superimposed structure. The characteristic of composite structure is better than the single absorber structure, which improves enhancement mechanism brought by the composite structure. Sample fabrication and experiments indicate reflectivity curve envelope reaches −10 dB in 2.15–18 GHz frequency range (relative bandwidth 157.3%), and the tunable absorption frequency range in low-frequency domain is greater than 1.3 GHz. The structure has good adaptation on TE and TM polarizations, as well as good angle insensitivity. This composite structure has application potential in intelligent response system related with electromagnetic compatibility, energy absorption and object security management.