Design of stacked wafers AMC at 920 MHz for metallic object detection in RFID application

Artificial Magnetic Conductor, AMC is introduced into RFID application to overcome the problem of metal object detection. The AMC act as the Perfect Magnetic Conductor, PMC exhibits a reflectivity of +1 (in-phase reflection). In this paper, the stacked wafers AMC structure is designed to operate at 920 MHz frequency. The proposed stacked wafers AMC is an evolution from the basic square patch AMC. By introducing different size of slots into the square patch will help to reduce the frequency hence increase the bandwidth of the reflection phase. Another method to increase the bandwidth is by increasing the thickness of the structure. For the single cell of stacked wafers AMC proposed in this paper, the simulated bandwidth is 3.5% with reduced size of 45.56% than the square AMC. An optimized structure of 3×2 stacked wafers AMC give better return loss = -21.8 dB and gain = 3.04 dB with total efficiency of 82.3%.