Design of a Compact Multilayer High-Gain Microstrip Patch Antenna for IoT Applications

A compact multilayer high-gain multiband U-slot microstrip patch antenna is presented in this letter. A multilayer antenna design consisting of five layers is proposed to increase both gain and bandwidth. In the first layer, a rectangular patch is printed on FR4 substrate, acting as the directional layer. The second layer comprises a U-slot rectangular patch printed on FR4 substrate, with the physical patch size being the same as that of the first layer. This layer is embedded on a third layer composed of polyethylene terephthalate glycol (PETG) material to improve antenna parameters, such as bandwidth and gain. The thickness of the PETG layer is optimized to achieve a higher bandwidth. The fourth layer, featuring a defected ground structure, forms the ground layer of the microstrip antenna. The fifth layer comprises a reflector, which is the largest laminate in the design. Both the fourth and fifth layers are printed on FR4 substrate. A prototype is fabricated and measured to verify the antenna design presented in this study. It is observed that the simulated and measured results of the antenna agree well, with the simulated antenna gain being 9.27 dBi. Overall, the proposed antenna design operates across four operating bands: 1,574-1,602 MHz, 1,959-2,030 MHz, 2,421-2,506 MHz, and 2,937-2,960 MHz.