Experimental Approach of Resonant Frequency Lowering Using ADM for Microstrip Circular Patch Antenna

The high permittivity of dielectric material is required to lower the resonant frequency of the microstrip circular patch antenna. An FR4 epoxy dielectric substrate frequently applied for the antenna deployment results in high losses due to its inherent characteristics, hence this leads to lower the efficiency. In this paper, an experimental approach to lower the resonant frequency of microstrip circular patch antenna by using artificial dielectric material (ADM) made of a modified styrofoam is proposed. By inserting a number of thin conductor wires into the styrofoam as a host material, the relative permittivity of host material could be increased. The electric fields distribution for TM_z resonant mode in the microstrip circular patch antenna becomes a reference for placing the thin conductor wires. The result of experimental approach shows that the ADM made of 110 pieces 0.5mm diameter thin conductor wires inserted into a styrofoam could significantly lower the resonant frequency of conventional microstrip circular patch antenna around 48% from 1832.3MHz to 951.2MHz. In other term, there is an increase of effective relative permittivity up to 270%.