Theory of Input Impedance of a Slot Antenna With Two Parasitically Excited Wires

This letter presents the formulation and validation of the theory of the input impedance of a slot antenna with two parasitically excited wires. First, the self-impedance of an inverted-L wire, the mutual impedance between the two inverted-L wires, and the mutual impedance between the slot and the inverted-L wire are derived under the commonly assumed electrically-thin condition for the slot and wires. Then, the input impedance of the slot with two parasitically excited wires is obtained with the self and mutual impedances. Finally, the theoretical values are compared with the full-wave simulated ones, and very good agreement is achieved.