Application of Resonant Matching Circuits for Simultaneously Enhancing the Bandwidths of Multi-band Mobile Phones

It has become a more and more challenging problem for antenna designers to guarantee a certain bandwidth for multi-band mobile phones, as the volumes of the terminals decrease and the operational bandwidths to cover are more and more numerous. Adding low loss resonators is a well-known technique for increasing the bandwidth in a given frequency band. In this article, it is shown that such reactive matching circuits may generally allow to enhance multiple non-contiguous bandwidths simultaneously without using any kind of switch. This point is illustrated thanks to microwave simulations, performed on a tri-band commercial mobile phone. Furthermore, a specific matching network is experimentally implemented on this phone, which allows to confirm the simulation results.