A novel multi-band antenna design with matching network for use in mobile terminals

Today's mobile terminals need to operate in more than one standard some of which are GSM850, GSM900, LTE 700 MHz and 2.5 GHz, DCS, PCS, W-CDMA and WLAN in order to comply with the user requirements. The mobile terminal antenna also needs to be highly efficient in these frequency bands, which means it shall have low reflection coefficient and high radiation efficiency. As known, an antenna should have a length approximately comparable to the operating wavelength for being an efficient radiator. For the lower frequency standards like LTE700, GSM850 and GSM900, the free space wavelength is very large in comparison to the size of a handheld terminal, which means that in a resonant approach, an electrically small antenna need to be coupled to the chassis. In this study, an electrically small antenna for a mobile terminal is designed for the communication standards mentioned before. Therefore, associated matching circuits are designed, integrated and optimized using passive lumped components to increase the total efficiency of the structure to an acceptable level. To cover all the standards mentioned before, a two branched matching network was designed each of which enables matching at different frequency bands.