Novel microstrip-monopole-integrated ultra-wideband antenna for mobile UWB devices

A small ultra-wideband antenna for mobile UWB devices has been developed theoretically and experimentally. The broadband operation of the antenna is achieved by integrating a single square-microstrip-patch with a monopole and by introducing a cylindrical-cap-loaded probe-feed and three tiny shorting-pins. This microstrip-monopole-integrated antenna is electrically easy to be integrated into printed circuit boards or plastic cases of the UWB devices, and also mechanically rigid to facilitate the reduction of the overall dimensions of the UWB devices. Sensitive to both vertically and horizontally polarized electromagnetic waves, it features a fractional bandwidth of around 1.5 with the center frequency of 6.1 GHz, which most likely satisfy the UWB frequency band requirements as proposed by the latest FCC Part15 specification. The planar dimensions of the antenna are less than 4 cm by 4 cm. The details of its design, analyses, and performance characteristics are presented and discussed.