A novel microstrip slot antenna for permittivity measurement

A compact Microstrip slot antenna is designed for 2.4GHz frequency and presented in this paper. The proposed antenna structure has multiple slots. The designed antenna is fabricated using FR4 substrate with 1mm thickness. This antenna has been implemented as a sensor for the measurement of dielectric constant of a liquid sample. The radiation characteristics and return loss are also analyzed. It is shown that the proposed antenna has relatively stable omni directional radiation pattern in the H plane and bidirectional radiation pattern in the E-plane and the return loss is above -14dB in the frequency range of 700 MHz-2.94GHz. As slot antennas are less sensitive to manufacturing tolerances compared to patch antenna it is well suited for industrial applications. The proposed resonator is fabricated and experimentally verified. A calibration equation relating the measured shift in resonant frequency and the dielectric constant has been established for determining permittivity.