Planar antenna plays an important role in Internet of Things (IoT) applications because of its small size, low profile and low cost. In IoT wireless module, antenna is typically occupied one-third size of overall circuit; therefore, planar antenna, i.e., integrated on printed circuit board (PCB) is one of attractive design. In this chapter, the fundamental of antenna is firstly discussed. Printed Inverted-F Antenna (PIFA) is taken as an example to explain the design process of simple planar antenna and a size-reduced 2.4 GHz ISM band PIFA is used for experimental explanation for the short-range IoT applications. Finally, a wideband antenna is shown as wideband planar antenna for short-range and long-range IoT applications.