M.R.P. Santos

Electrical properties of the electroceramic composite in the microwave frequency range: Pb(Fe0.5Nb0.5)O3 (PFN)–Cr0.75Fe1.25O3 (CRFO)

In this paper, a new electroceramic composite [Pb(Fe0.5Nb0.5) O3 (PFN)]Z [Cr0.75Fe1.25O3 (CRFO)]100−Z (Z = 0, 10) is investigated in the microwave (MW) frequency range. The dielectric permittivity and loss in the region of 4–8 GHz (G and H MW bands) were studied. The performance of cylindrical resonator antennas based on CRFO100 and on PFN10 was examined. The experimental and theoretical results of the dielectric resonator antenna (DRA) such as return loss, bandwidth, input impedance and radiation patterns are in good agreement for both composites: PFN10 (10% PFN + 90% CRFO) and CRFO100 (100% CRFO). A numerical validation was made considering an air gap between the dielectric resonator and the metallic conductors. The PFN10 matrix composite PFN10 (10% PFN + 90% CRFO) presents the highest dielectric permittivity (9.9 at 4.44 GHz) and the lowest bandwidth (9.9%). The CRFO100 phase (100% CRFO) presents a dielectric permittivity of 8.35 at 4.67 GHz and a bandwidth of 11.8%. The Hakki–Coleman procedure was also used in this study. The dielectric permittivity of 8.35 (tan δ = 1 × 10−3) at 7.94 GHz was obtained for CRFO100. The PFN10 presents a dielectric permittivity of 10.17 (tan δ = 4.9 × 10−3) at 7.05 GHz. These measurements confirm the possible use of such material for small DRAs.