Electrical properties and RF energy response of metal loop antennas for wireless sensing and detecting of conductive and non conductive materials

A number of loop antennas designed to operate at UHF ISM band 2.4-2.5 GHz have been investigated. Four types of loop antennas were designed and fabricated including the circular wire loop, square loop, circular plate loop, and disk loop. The circular plate loop has been incorporated into the RF sensing and detection peripheral due to its excellent practical performance. It was examined in various types of wireless environments where the complex object/ material both conductive and non conductive existed. In this paper, each type of antennas was also tested, numerically and experimentally, to obtain its individual electrical properties such as S₁₁, VSWR, and radiation pattern.