Designing a PIFA for WLAN WiFi™ Applications
This example discusses the PIFA designed for Wi-Fi™ applications . The Planar Inverted-F Antenna(PIFA) is basically a grounded patch antenna with the patch length of $\lambda$/4 (open-short microstrip resonator) instead of the conventional $\lambda$/2 for the patch antenna (open-open microstrip resonator). It typically consists of a ground plane, a top patch grounded at one end, and a coaxial probe feeding the top patch. The PIFA is commonly used in mobile communications since it has low manufacturing cost, smaller than the patch antenna size, and a relatively simple structure. In addition it also has reduced backward radiation towards user's head. However, the patch antenna has better polarization purity. Hundreds of PIFA varieties have recently been developed for mobile phones.