New Techniques for Increasing Antenna Bandwidth with Impedance Loading

New methods are presented for increasing the bandwidth of wire antennas using impedance loading. This paper extends the seminal Wu-King theory of the internal impedance profile that produces travelling-wave only current modes on a center-fed dipole antenna. It also presents a numerical optimization methodology based on Central Force Optimization, a new deterministic multidimensional search and optimization metaheuristic useful for problems in applied electromagnetics. A CFO-optimized loaded monopole antenna is described in detail and compared to the same structure loaded with a fractional Wu-King profile. The CFO monopole generally performs better than other designs using either the full or fractional Wu-King profiles or the extended Wu-King profiles. The methods described in this paper should be useful in any wire antenna design that utilizes impedance loading to increase bandwidth.