Multiband Antenna ${Q}$ Optimization Using Stored Energy Expressions

A method to compute antenna Q from a single frequency current distribution is applied to the optimization of multiband radiating structures. A genetic algorithm produces suboptimal structures in the sense of simultaneous multiband minimum Q. These structures model in a simplified manner common wireless communication devices. The comparison to the physical bounds for the considered situations shows that the suboptimal structures perform close to their limitations. Matching networks are designed using real component models with a commercial tool. These networks have less than three components and provide less than -6.5 dB reflection coefficient magnitude in all considered bands. The results show that the single-frequency Q estimation method may be useful for antenna design.