Frequency reconfigurable planar inverted F antenna (PIFA) with software-defined match control

In the present work, a frequency-agile antenna is obtained by integrating a simple planar inverted F antenna (PIFA) with a programmable impedance tuner. The tuner, the software-defined match control (SDMC) circuit, uses a microstrip loaded line structure with three stubs that are each terminated by a varactor diode. The spectral response of the input match is obtained by varying the voltage bias and thus the capacitance of the varactor diodes. The tuner only controls the impedance match between the PIFA and the 50-ohm design impedance of the internal RF circuits.