Built‐in antenna design for 2.4 GHz ISM band and GPS operations in a wrist‐worn wireless communication device

A compact monopole and inverted‐F antenna design for 2.4 GHz ISM band (2400–2485 MHz) and 1.575 GHz GPS operations suitable to be embedded within a wrist‐worn wireless communication device is presented. Those antennas are fabricated on a polycarbonate and acrylonitrile‐butadiene‐styrene blend substrate with a three‐dimensional etching process for irregular plastic materials. The wrist‐worn device with and without a solid hand phantom model is evaluated. The radiation efficiency of the antennas can reach 80% for the ISM band and 63% for the GPS band without the hand phantom model. With the hand phantom model, the radiation efficiency reduces in half for both the ISM and GPS bands due to lossy materials in the phantom model. Good agreements between simulations and measurements are obtained. Moreover, the specific absorption rate of the device for the ISM band is measured and the results are much lower than the limit required by the FCC. This build‐in antenna design can be applied in the wearable wireless communication device.