Volume 26 Issue 4 - April 11, 2014 PDF
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High-Q dielectrics using ZnO-modified Li2TiO3 ceramics for microwave applications
Cheng-Liang Huang*, Yu-Wei Tseng, Jhih-Yong Chen
Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan
 
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The microwave dielectric properties of the (1–x)Li2TiO3xZnO (x = 0.1–0.5) ceramic system prepared by mixed oxide route have been investigated. The rock-salt structured (1–x)Li2TiO3xZnO were characterized by using X-ray diffraction spectra, scanning electron microcopy (SEM). The dielectric properties are strongly dependent on the compositions, the densifications and the microstructures of the specimens. The decrease of Q×f value at high-level ZnO addition (x > 0.3) was owing to the intensity of the (002) superstructure reflection decreased and became disordered rock-salt structure. For practical applications, a new microwave dielectric material 0.7 Li2TiO3–0.3ZnO is suggested and it possesses a good combination of dielectric properties with an εr of ~ 22.95, a Q×f of ~ 99,800 GHz (measured at 8.91 GHz), and a τf of ~ 0 ppm/°C. A low-loss dielectric resonant antenna using aperture-coupled cylindrical dielectric resonant was designed and fabricated using the proposed dielectric to study its performance.

Table 1 Microwave Dielectric Properties of (1–x)Li2TiO3xZnO Ceramic System Sintered at Different Temperatures for 2 h.


Fig.2. (a) Physical layout of the low-loss dielectric resonant antenna using aperture-coupled cylindrical DR antenna fed with microstrip line and fabricated aperture-coupled cylindrical DR antenna: (b) top and bottom view.


Fig. 2. (c) The simulation and measurement return loss of DR antenna fed with microstrip line.
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