Numerical Simulation And Experimental Study On The Microwave Metamaterial Band-pass Filter

Metamaterial is an artificial composite material consisting of periodic unit cell structure,which possesses extraordinary physical properties while some natural materials do not have,such as the negative refractive index,reversed doppler effect.Metamaterials have attracted tremendous interest owing to their potential applications in engineering.Based on the design philosophy of metamaterials,we can achieve several band-pass filters with higher performances through elaborate design.In this thesis,we present four metamaterial band-pass filters based on metal-dielectric-metal(MDM)sandwiched structure in the microwave regions and their filtering performances have been studied both theoretically and experimentally.The main contents are listed as follows:(1)Two multi-band metamaterial band-pass filters are designed based on the MDM structure.The results indicate that there are two distinctive passbands for the dual-band band-pass filter with broad bandwidths(-3 d B)of 3.50–4.55 GHz and 7.69-8.55 GH within 0-12 GHz,which centered at frequencies 4.03 GHz and 8.12 GHz with transmission rates of-0.30 dB and-0.25 dB in the transmission spectra,respectively.Moreover,there are three different passbands with broad bandwidths(-3 dB)of 5.35-6.80 GHz,8.33-9.75 GHz and 11.12-12.43 GHz within 4-16 GHz for the tri-band band-pass filter,which centered at frequencies 6.07 GHz,9.04 GHz and 11.77 GHz with transmission rates of-0.15 dB,-0.28 dB and-1.09 dB in the transmission spectra,respectively.These two designed filters have advantages of high transmission,multi-band,polarization-insensitive and stable wide-angle response.Additionally,the filtering properties can be improved by introducing the substrate integrated waveguide(SIW)technology.(2)Two tunable metamaterial band-pass filters are designed based on the MDM structure.The study shows that there is one resonant frequency within 8-12 GHz for the mechanically tunable band-pass filter,which can be tuned linearly and continuously by changing the relative distance of two MD structures.In addition,there is just one resonant frequency with 4-10 GHz for the electrically tunable metamaterial band-pass filter without feeding network,which is determined by the capacitance of variode.Meanwhile,our study also shows that there are two resonant frequencies with the presence of feeding network into structure and one is adjusted by the capacitance,while the other is unchanged which arises from the feeding network.These four designed metamaterial filters with various filtering properties can be used as band-pass filters and may have important appIications in microwave communication,imaging and military fields.