Miniaturization of a Filter-Antenna Device by Co-Design

This paper presents a novel miniaturization approach by co-designing together a filter and an antenna. Indeed, contrary to a classical filter-antenna design, which presents a 50 Ω transition between the filter and the antenna, the co-design methodology proposed in this paper will prove that both the antenna and the filter can be optimized on a complex impedance. For this impedance, different from 50 Ω, the antenna volume can be reduced by more than 50% while presenting a high radiation efficiency. Moreover, the filter performance will be optimized on complex impedance loads without being affected compared to a classical 50 Ω filter. This new approach will be detailed and compared to a classical one in order to validate the improvement achieved by this co-design methodology. Prototypes have been manufactured and measurements confirm the benefits observed during the design phase.