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In the characteristic basis function method (CBFM) for the wide-angle electromagnetic scattering problems of electrically large objects, the low generation efficiency, and many characteristic basis functions exist due to the dependence on external excitation. This paper proposes a characteristic mode basis function method (CMBFM) with novel basis function construction to address this issue. In CMBFM, characteristic modes of each extended block obtained by dividing objects are calculated separately, and then the effective modes are selected as basis functions according to the modal significance. Compared with CBFM, the time performance of constructing basis functions is improved significantly. Furthermore, fewer basis functions are generated without a loss of accuracy. The corresponding numerical results demonstrate that significant efficiency and accuracy can be achieved by the proposed approach. [ABSTRACT FROM AUTHOR]

In this communication, a stub-loaded reconfigurable broadband metamaterial absorber (MMA) based on lumped components is proposed and experimentally verified. An absorption bandwidth of 6.3 GHz is realized with more than 90% absorptivity ranging from 8.3 to 14.6 GHz (the relative bandwidth reaches 55%) by selecting certain values of resistors and inductors. The parameter analysis of the loaded stubs illustrates their vital influence on enlarging the absorbing bandwidth. In addition, the designed absorber has good performances on polarization-insensitiveness and wide angles of incident waves for both TE and TM polarization. The waveguide measurement method is utilized to verify the simulated results of the reconfigurable broadband MMA. [ABSTRACT FROM PUBLISHER]

In this research, a new tunable dual-band metamaterial absorber with wide-angle TE and TM polarization stability is proposed. The designed absorber exhibits two high absorption peaks at 5.1 and 8.5 GHz with absorption peaks of 96 and 97%, respectively. The unit cell consists of a metallic background plane and two closed rings including two groups ofT-shaped resonators, separated by a low-cost dielectric layer with thickness of 0.9 mm. By tuning the distance between theT-shaped structures and closed ring, the corresponding two resonance frequencies can be effectively separated with high absorption over 95% while keeping the closed ring unchanged. The simulated results demonstrate that the designed absorber has good characteristics of high absorption rates, polarization-insensitiveness and wide angle of incident waves. A waveguide experiment is performed to verify the good agreement between the simulated and measured results. [ABSTRACT FROM AUTHOR]