A Formulaic Model Calculating the Permittivity of Testing Materials Placed on a Circular Patch Antenna

In this study, a formulaic model optimized by artificial bee colony (ABC) algorithm is presented for calculation of the relative permittivity of testing materials which placed on a coaxial-fed circular patch antenna (CPA). The CPA with patch diameter of 34 mm and thickness of 1.6 mm is designed for operating at a resonant frequency of 2.37 GHz. Solid materials to be tested, having a thickness of 2 mm and the patch diameter size, are placed on the antenna patch. Therefore, the resonant frequency and the quality factor of the CPA with the material would change depending on the permittivity of the solid material. The resonant frequency and the quality factor of the CPA with various solid materials (the relative permittivity from 1 to 100) are obtained by simulations. An optimum model is fitted by the ABC through the simulation data for calculation of the permittivity of testing solid material. The model is also verified over the calculated permittivity for three testing materials. Therefore, the permittivity of a testing material can be accurately determined by the model without using numerical or analytical electromagnetic solutions.