Experimental and numerical investigation of the microwave dielectric properties of the MgTiO3 ceramic matrix added with CaCu3Ti4O12

P.W.S Oliveira,G.F.M Pires Junior,A.J.M Sales,H.O Rodrigues,A.S.B Sombra

doi:10.1590/2179-10742017v16i2794

Abstract

This paper describes an experimental and numerical investigation of the dielectric resonators based on the MgTiO 3 ceramic matrix, which relates to their dielectric properties in microwave. The resonators are compounds of the MgTiO 3 added with 4, 6, 8, 10 and 12 wt% of the CaCu 3 Ti 4 O 12 . The manufacturing process of the resonators is based on the solid-state method. The properties of the permittivity and dielectric loss are elucidated using the Hakki and ColemanÂ´s method. The experimental measurements of the dielectric resonators, acting as antennas, provide some results as return loss, gain, efficienty, bandwidth and input impedance. These results are coherent with the numerical investigation. The addition of the perovskite CaCu 3 Ti 4 O 12 in the MgTiO 3 ceramic matrix increased the value of the dielectric constant and it was obtained a higher value of 21.01 for the sample MgTiO 3 added with 12% CaCu 3 Ti 4 O 12 . The temperature coefficient of resonant frequency (t f ) was measured for all the samples and the best value obtained was 9.62 ppm/Â°C for the sample MgTiO 3 added with 12% CaCu 3 Ti 4 O 12 . The material duly proposed, shows to be promising for applications as dielectric antennas and this study point out that it is possible to obtain a dielectric resonator antenna (DRA) with a temperature coefficient of resonant frequency close to zero.

Highlights

The Magnesium titanate (MgTiO3) ceramics, commonly called the MTO, is a popular dielectric material applied in microwave frequencies
We report the study of the dielectric constant and the dielectric loss of resonators, based on the MgTiO3 ceramic matrix added with the CaCu3Ti4O12, and the temperature coefficient of resonant frequency ( f) in this composite
This study describes an experimental and numerical investigation of the dielectric properties in microwave of the ceramic resonators matrix, based on the MgTiO3

Summary

Introduction

The Magnesium titanate (MgTiO3) ceramics, commonly called the MTO, is a popular dielectric material applied in microwave frequencies. The MTO has the ilmenite type structure and applications in a microwave frequency range, it exhibits a good quality factor, a low dielectric constant and a temperature coefficient of resonant frequency τf ∼−50 ppm/◦C [1]. The MTO is an attractive resonator among microwave materials due to its promising dielectric properties, with moderately high values in quality factors, due to the low cost of raw materials. The main objective of the present study is to form a composite ceramic to optimize the performance of this particular material, introducing a second phase with a high dielectric constant (>105), over a wide range of frequency, from -50 oC to 300 oC [2,3]. The CCTO is considered a good candidate due to its high dielectric constant and a temperature coefficient of resonant frequency τf positive. The composite MTO-CCTO has thermal stability due near zero temperature coefficient of resonant frequency

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