Metamaterial Absorber And Its Application To Antenna Stealth Technology

Metamaterial absorber(MA)is a kind of artificial material which can absorb the incident electromagnetic wave and change the electromagnetic energy to heat.With the safety consideration of military,the requirements of antenna stealth technology has been increasingly recognized recently.This dissertation presents researches on the MA and its application to reduce the Radar Cross Section(RCS)of microstrip antenna array to 10 d B without affect the radiation properties.The main contributions of the thesis are listed as followings:1.Two kinds of MA are introduced.First,a polarization-independent and angle-insensitive metamaterial absorber is proposed.For our MA design,we make 4-fold rotational symmetric operation of the split-ring-resonator(SRR)unit cell,which leads to polarization independent property.Meanwhile,the MA constructed with subwavelength unit cells can offer angle-insensitivity property.Then,a broadband MA loaded with lumped resistors is proposed.The polarization-independent and angle-insensitive MA is fabricated using PCB technology.The NRL arch experimental measurements is used to test the absorption of MA.The simulation results agree with the experimental results.2.The relationship between MA absorption and RCS reduction is studied by introducing the concept of polarization rotation.It is proved by the three dimensional full wave simulation software that the absorption of MA and the RCS reduction is linear correlation only when there is no polarization rotation of incident waves,thus this kind of MA can be employed for RCS reduction effectively.This provides strong support and reference value for the application of MA to RCS reduction.3.A microstrip array antenna with a wideband and low RCS is proposed.The broadband MA is loaded on top of the antenna array,forming an integrated structure.Before and after loading,there is little difference to the working bandwidth,the matching performance,the radiation patterns and the gain of the antenna array,while the monostatic RCS of it has been efficiently reduced in a wide frequency range,with the maximum reduction reaching as much as 13 d B.