A compact ground-slitted CPW-fed polarization reconfigurable antenna for wireless LAN applications

Here, a small, CPW-fed monopole antenna with reconfigurable polarization is introduced. Two stubs positioned at each side of the monopole radiator are connected to the ground plane via two p-i-n diodes to achieve an asymmetric ground plane. Two horizontal slits inside the ground plane assist in increasing the impedance matching. The antenna either produces linear polarization or left/right circular polarization, depending on the p-i-n diode's switching state. The structure was fabricated, and its performance was evaluated to confirm the planned design. At 5.8 GHz frequency, the requisite S11 bandwidth (IBW) and axial-ratio (AR) bandwidth is attained by correctly incorporating the stubs and slitting the ground plane. Two C-shaped metal strip is loaded on top of the substrate layer to increase the AR bandwidth. The measured impedance bandwidth is 5.50-6.10 GHz (600MHz, 10.34%) and the AR bandwidth is 5.52-6.0 GHz (480MHz, 8.62%) for circular polarization and 5.25-5.81 GHz (560MHz,10.18%) impedance bandwidth for linear polarization. With a maximum CP gain of 3.8 dBic, the suggested antenna displays a nearly uniform gain over the operational AR bandwidth. The recommended antenna is appropriate for higher frequency WLAN applications and has a compact structure with a large 3dB AR bandwidth.