Microstrip antenna on a high dielectric constant substrate : BaTiO3 (BTO)-CaCu3Ti4O12(CCTO) composite screen-printed thick films

• Published in: Journal of electronic materials 2006-10, Vol.35 (10), p.1848-1856
• Main Authors: FECHINE, P. B. A, TAVORA, A, KRETLY, L. C, ALMEIDA, A. F. L, SANTOS, M. R. P, FREIRE, F. N. A, SOMBRA, A. S. B
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Dielectric loss and relaxation; Dielectric properties of solids and liquids; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Materials science; Materials synthesis; materials processing; Permittivity (dielectric function); Physics
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-006-0167-0

The performance of microstrip antennas using composite thick films of (BTO-BaTiO3) and CCTO (CaCu3Ti4O12) as a substrate were studied. The dielectric permittivity and loss of (BTO)x-(CCTO)1-x thick films with x=,0.,0.,0.,0.9, and 1 were examined. These films were prepared in two-layer geometry using the screen-printing technique on Al2O3 substrates. Mechanical alloying followed by the solid-state procedure was successfully employed to produce powders of CCTO (CaCu3Ti4O12) used in the films. We also studied the films dielectric permittivity (K) and loss (D) in the medium-frequency (MF) range (100 Hz to 1 MHz). The performance of a planar microstrip antenna that uses the (BTO)x:(CCTO)1-x thick films as a substrate of high K was also examined in the microwave range of frequencies. From the analysis of the antenna operation of the samples, one can conclude that the higher values of K in the range of 2.5-3.3 GHz antennas is presented by the BTO substrates. For the BTO film, the K value is ~66 (2.6 GHz) and decreases to 34 for the CCTO film (3 GHz). For the BTO and CCTO films, the antenna bandwidths (BW) are ~50% and ~38%, respectively. The higher bandwidth presented by the BTO compared to the CCTO is certainly associated with the higher loss presented by the BTO phase, which is a ferroelectric phase. Therefore, these measurements confirm the potential use of such materials for small microwave planar antennas, where the miniaturization of the devices is crucial.