Ultra-Wide Bandwidth Enhancement of Single-Layer Single-Feed Patch Antenna Using the Theory of Characteristic Modes

The Theory of Characteristic Modes (TCM) is proposed as a systematic approach to antenna design to achieve the goal of finding the antenna structure with optimum broadband behavior. This theory provides a physical insight to the radiating nature of microstrip patch antennas and reduces the design optimization time. In this work, the resonant behavior of the highly radiating structure of the single U-slot rectangular patch on a single-layer epsilon(r) = 4.4 substrate is analyzed using TCM. Modal analysis of this single-layer structure with different single feed excitations concludes that VSWR <= 2 impedance bandwidth in the order of 96% can be achieved with a single T-probe feed. Experimental results, included here, show VSWR <= 2 impedance bandwidth in the order of 71%.