Slim planar composite antenna with two orthogonal polarisations for WLAN router applications

A slim planar composite antenna for WLAN router applications is presented. A J-antenna and a dipole antenna are proposed as components antennas for the vertical and the horizontal polarisations, respectively. The arms of the dipole adopt a bent structure for size miniaturisation. For tuning the impedance matching, a matching stub is introduced working as a parallel inductor on the upper part of the dipole. The antenna is made by copper and fed by coaxial lines. The final antenna achieves two orthogonal polarisations with a low cross-polarisation level <;-18 dB, a return loss better than 10 dB, and port isolation in excess of 19.3 dB from 2.38 to 2.51 GHz, thus making it suitable for use in 2.45 GHz WLAN router polarisation diversity applications. The slim planar structure with 25.5 mm width and light weight makes it easy to install on WLAN routers.