Frequency reconfigurable planar inverted-F antenna using switchable radiator and capacitive load

A frequency reconfigurable planar inverted-F antenna (PIFA) using real PIN-diodes is presented for mobile worldwide interoperability for microwave access (m-WiMAX) applications. This antenna not only alters the frequency band of the m-WiMAX using PIN-diode switching, but it also has a small profile using capacitive load within an FR4 dielectric constant substrate. The PIFA consists of the following: a main radiator, an additional radiator, a band-switchable capacitive load, two PIN-diodes and control circuits. One diode is placed between the main and additional radiator on the top side, and the other is vertically attached between the capacitive load and ground. Depending upon whether the diodes are on or off, the antenna operates over 2.3-2.4, 2.5-2.7 and 3.4-3.6 GHz for worldwide m-WiMAX bands. To investigate the effect of load capacitance, a parametric analysis is performed by sweeping the length and width of the capacitive load. All simulated and measured results for the proposed antenna are presented, and they show excellent agreement.