A miniaturized Microwave Bandpass Filter Based on Modified (Mg_0.95Ca_0.05)TiO₃ Substrate

¹ College of Bigdata and Information Engineering, Guizhou University, Guiyang, Guizhou 550025, China
² Department of Physics and Electronics, Liupanshui Normal University, Liupanshui, Guizhou 553004, China
³ College of Electrical Information, Huanggang Normal University, Huanggang, Hubei 438000, China

^* Corresponding author, email address: zding@gzu.edu.cn

Abstract

A microwave miniaturized bandpass filter using (Mg_0.95Ca_0.05)TiO₃ (abbreviated as 95MCT hereafter) ceramic substrate is investigated in the present paper. The paper studies the sintering and microwave dielectric properties of Al₂O₃, La₂O₃ and SiO₂ co-doped 95MCT. The XRD pattern shows that a secondary phase MgTi₂O₅ is easily segregated in 95MCT ceramic, however, through co-doping it can be effectively suppressed, and the microwave dielectric properties, especially, the Qf value can be significantly improved. Through optimizing the co-doping ratio of Al₂O₃, La₂O₃ and SiO₂, the sintering temperature of 95MCT ceramic can be lowered by 80°C, and the microwave dielectric properties can reach Qf=61856GHz and ε_r=19.84, which indicates the modified 95MCT ceramic have a great potential application in microwave communication devices. Based on this, we also designed a miniaturized microwave bandpass filter (BPF) on modified 95MCT substrate. Through a full wave electromagnetic structure simulation, the results show that the center frequency of the BPF is 2.45GHz and the relative bandwidth is 4.09% with the insertion loss of less than 0.2dB in the whole bandpass.