Dielectric composite materials made of polymers and ferroelectric ceramics have recently emerged as one of the important components for applications involving the generation, transformation, and storage of sustainable energy. Because there is a trade-off between dielectric permittivity, dielectric loss, and dissipation factor, the end use is the energy storage capacity. In the present study, epoxy resin (RE)/barium titanate (BaTiO3) composite samples are prepared using the mixture cast method with new molds. The dielectric properties, such as dielectric permittivity, dielectric loss, electrical modulus, static conductivity and dissipation factors due to the concentration of barium titanate and frequency effect on the composites, are examined using two characterization methods. The objective of this study is to determine the dielectric permittivity of the material using two microwave methods, the first is time domain spectroscopy (TDS) and the second is on the X-band microwave test bench (MTB). Additionally, different empirical mixture laws are used to estimate the dielectric permittivity of our composites. It is found that an increase in filler concentration (BaTiO3) increases the effective dielectric permittivity, which is confirmed with different empirical mixture models. The findings of this research can be used for electrical devices, including sensors, wave absorbers, resonators, and antennas.