Research On Frequency Selective Surfaces Based On Electromagnetic Metamaterial

Based on the FSS technologies in miniaturization and multiband, both passive and active FSSs are studied in this paper. For the passive FSS, two miniaturized tri-band combined-element FSSs are designed and verified. For the active FSS, an absorptive FSR that can absorb out-of-band signals while ensuring the normal transmission in band is designed by loading lumped resistors in the FSS. A novel AFSS that can either transmit or reflect 2.45 GHz WLAN signals is proposed by loading PIN diodes. This thesis is summarized as follows:(1) Study on the multi-band miniaturized FSS. Two miniaturized, tri-band and combined-element FSSs are designed and verified. Multi-band properties can be realized effectively by combining FSS structures with different resonant points. The complementary meandering structure is used to miniaturize the designs, which delays the grating lobe and improves the stability for different incident angles and different polarizations. The ECM is applied to prove the simulation results.(2) Study on the miniaturized FSR with wideband absorbing properties. Indicators such as the resonant frequency, the-3 d B bandwidth and the insertion loss of the SSA structure are analyzed when basic lumped elements such as capacitors, inductors and resistors are loaded, and its effect laws are summarized. An absorptive FSR that absorbs out-of-band signals while ensuring the normal transmission in band is designed to reduce the bistatic RCS of the radome.(3) Study on the active reconfigurable FSS. Reconfigurable FSSs loaded with PIN diodes and varactors are analyzed and simulated with the ECM theory and the simulation software, respectively. To understand the gradual switching procedure of the FSS loaded with PIN diodes between two modes(ON state/OFF state), the induced electric field distributions on the FSS element under conditions of different equivalent resistors are presented. Besides, the rear feeding network's negative effects on the characteristics of the AFSS in two states are studied.(4) Study of the AFSS without feeding network. A novel AFSS without feeding network is designed and verified. It transmits 2.45 GHz WLAN signals in the ON state and functions as a band-stop filter to shield those signals in the OFF state. A special topology that requires no additional biasing lines is applied to weaken the negative effects of the feeder network. Circular apertures are employed in the structure to satisfy the need of ventilation and heat dissipation.