Mobile terminal antennnas implemented by using direct coupling

The current trend in mobile terminals is an increasing number of systems. The volume occupied by the antennas of the radio systems is becoming more and more problematic and new low-volume antenna solutions are needed. Since the EMC shielding and the ground plane operate as the main radiating structure especially below 1 GHz, a very small antenna structure can be achieved by using a direct feed, i.e. galvanically inducing currents on the surface of the chassis. The feed can be placed over an impedance discontinuity, e.g. formed by a slot. Using this approach, an antenna structure for a small handheld digital television (DVB-H) receiver is presented. The antenna gain exceeds the specification by a 4-dB margin. The introduced antenna structure can also be used for multi-system terminals.