Research On Metamaterial Absorbers Using Frequency Reconfiguration Technique

Excellent radar absorbing materials (RAM) can achieve stealth of weaponry such as militaryaircrafts and ships, and can also improve electromagnetic environment of weapons platforms.Therefore it has so high value to study on radar absorbing materials for strengthening national defenseand enhancing army battle effectiveness. However, traditional RAM, once designed and manufactured,cannot be adjusted such as resonance frequency and band. It can’t be adaptive to complex and unfixedelectromagnetic environment. Active radar absorbing material is one of hot topics of smart radarabsorbing materials, which can absorb flexibly and adjustably.This thesis focuses on tunable metamaterial absorber, which has polarization insensitive andwide-angle microwave absorbing properties, and is presented as follows:1The frequency reconfigurable characteristic of the tunable microwave absorber is demonstratedby means of equivalent-circuit model．The design steps of the microwave absorber are summarized.And several structures of absorbers are designed with HFSS software under this method. Theinfluences of various structure parameters on the absorption characteristics are analyzed.2Polarization insensitive and wide-angle tunable microwave absorbers are studied, and somenew structures are designed. The performance of the new square-loop absorber structure is improvedin this respect, so does the new cross-loop structure. Then a new Jerusalem-loop tunable radarabsorber is designed, and which has the advantage of low-sensitivity to TE/TM waves with differentincident angles and polarizing angles．3Wideband and wide-angle tunable microwave absorbers are studied, and some new structuresare designed. Resonance characteristics of the dual-band absorbers are analyzed. Thedual-square-loop and hexagon-loop absorbers are designed. The simulating results show that each ofthem has realized a wide-band strong absorption, and they are all polarization-insensitive andangle-wide.