In this paper, a planar inverted-F antenna (PIFA) for Internet Of Things (IOT) networks is studied. The proposed structure covers the 868MHz radio frequency band used by LoRaWAN, Sigfox, Z-Wave and ZigBee in Europe and the 2.4GHz radio frequency band used for Zigbee, Bluetooth and WiFi in all the world. The miniaturization in the antenna size is achieved by introducing a meandered microstrip line and the setup of a short line between the resonant element and the ground plane. The antenna has compact size of 100x40x1.6mm3. The radiation patterns in the operating bandwidth are almost the same as the omnidirectional characteristics. The optimization of the antenna parameters was performed by CADFEKO, a Method of Moment (MoM) based solver.