Inverted-F Antenna for 3D Integrated Wireless Sensor Applications

This paper presents a low-profile inverted-F antenna for 3D integrated wireless sensor applications at the 2.4 GHz "industrial, scientific, medical" band (ISM). The proposed antenna with an equivalent model of the 3D integrated wireless sensor was simulated assuming in free-space conditions and fabricated on a piece of thick commercial FR-4 epoxy laminate combined with a stair configuration metal block. Both the impedance and radiation performance of the proposed antenna integrated in the wireless sensor cube were experimentally measured and then optimized. The measurements show that about 60 MHz -10 dB return loss bandwidth and -8.3 dBi gain are achieved at 2.4 GHz. Although the proposed antenna has low radiation efficiency due to the limited available space and the lossy epoxy based FR-4 substrate, it features a low-profile and cost effective solution for the particular applications.