Compact ACS-fed UWB antenna for diversity applications

A compact asymmetric coplanar strip (ACS)-fed ultra-wideband (UWB) antenna for diversity applications is presented. The proposed antenna is composed of two circular radiating elements and orthogonal ACS-fed mechanisms to achieve diversity performance across the UWB from 2.66 to 11.08 GHz, and occupies a very compact size of 28.5 × 28.5 mm². By introducing a rectangular stub diagonally between the two circular radiating elements, an interport isolation better than 15 dB is achieved. Furthermore, the proposed antenna shows nearly omnidirectional radiation patterns, stable gains and a low envelope correction coefficient. The simple feeding structure, compact size and uniplanar design make it easy to be integrated within the portable device for wireless communications with diversity operations.