Experimental and numerical investigation of dielectric resonator antenna based on the BiFeO3 ceramic matrix added with Bi2O3 or PbO

In this paper is reported an experimental and numerical investigation of the microwave dielectric properties of BiFeO3 (BFO) ceramic matrix added with 3 and 10 wt% of Bi2O3 or PbO, obtained through a new procedure based on the solid-state method. The experimental and theoretical characteristics of the resonator like return loss, bandwidth, input impedance are in good agreement. The simulations of radiation patterns are presented. For BFO reference sample, frequency response bandwidth is of 6.40% (simulated) and 7.18% (experimental) for frequency operation around 2.94 GHz. The BFO reference sample showed a dielectric permittivity around 25, with loss around 10−2. The adding of bismuth oxide (3 and 10 wt%) reduced the value of the dielectric permittivity as well as lead oxide 3 wt%, otherwise only the adding of 10 wt% increases its value. The temperature coefficient of resonant frequency (τf) was also measured for all dielectric samples. The values obtained were in the range of −517 ppm °C−1 to −222 ppm °C−1. With the addition of lead oxide was observed a deterioration of the thermal stability of the ceramic, with respect to the central frequency of resonance. The results obtained confirm the necessity of producing composites of this material with others positive τf materials for obtaining dielectric resonator antennas with τf ∼ 0.