Design of a Near-Field RFID Antenna Array in Metal Cabinet Environment

A four-element near-field radio frequency identification (RFID) antenna array for smart telecommunication cabinet is proposed to achieve a uniform electric field distribution in the target interrogation zone in a metal cabinet environment. In order to determine the distribution of excitations that generate the desired uniform near-field distribution, the method of maximum power transmission efficiency has been used. By introducing more than one test receiving antennas in the interrogation zone and maximizing the power transmission efficiency between the array to be designed and the test receiving antennas, an optimized distribution of excitations can be obtained and then realized by a feeding network. The designed reader antenna is demonstrated to be able to track all the tags inside the metal cabinet and can be easily adjusted to various cabinet configurations.