Analysis on Harmonic Radiation of Capacitively Loaded Tunable PIFA Based on Equivalent Circuit

A novel method based on a wideband equivalent circuit model is proposed to analyze the harmonic radiation of a tunable Planar Inverted-F Antenna (PIFA) tuned by a varactor. The nonlinear relationship between the input power, DC bias voltage and the dynamic RF voltage over the varactor are quantified for a single-band prototype. The radiation power is simulated at the first and second harmonic frequency. The verification is finally presented by measurement. Index Terms – Tunable antenna, PIFA, Harmonic radiation, Equivalent circuit