Characteristic Modes Theory: A Technique for Incresing the PIFA Antennas Bandwidth

PIFA antennas are narrow-band antennas. Several techniques have been developed for increasing bandwidth, but they have the disadvantage of cluttering the radiating plane and increasing the overall size of the antenna. To overcome these drawbacks, we propose the use of characteristic mode theory for extending the PIFA antennas bandwidth. We will first study the characteristic modes of a rectangular ground plane of dimensions
$\mathbf{120}\times \mathbf{60}\mathbf{mm}\mathbf{2}$
. Next, we'll use a PIFA antenna to extract all the resonant modes from the ground plane at their respective resonant frequencies. Finally, to show that characteristic modes are among the increasing bandwidth techniques, a comparative study will be made of the characteristics of the PIFA antenna exciting a mode and an antenna not exciting a mode.