Reconfigurable Multiband Extended U-Slot Antenna with Switchable Polarization for Wireless Applications

This paper proposes a reconfigurable multiband extended U-slot antenna with polarization diversity for wireless applications. The antenna is able to switch among linear polarization (LP) and left-hand (LH) and right-hand (RH) circular polarizations (CPs) for 2.4-/5.8-GHz wireless local area network (WLAN) systems. The antenna is composed of an extended U-slot patch with modified ground plane and two p-i-n diodes to switch the slots at ON- and OFF-states. The p-i-n diodes are appropriately positioned to change the length of the slot arms, which alters the antenna´s polarization with frequency diversity to operate in four states. The simulated and measured results verified the effectiveness of the proposed antenna configuration. The experimental bandwidths of the 10-dB return loss for RHCP and LHCP of 2.4-GHz WLAN are similar about 320 MHz (2.3-2.6 GHz), whereas for LP, the bandwidth is about 500 MHz (2.4-2.9 GHz). The bandwidths of the 3-dB axial ratio for the RHCP and LHCP states are about 400 MHz on the broadside direction for 2.4-GHz WLAN. The bandwidths for RHCP and LHCP of 5.8-GHz WLAN are about 500 MHz (5.6-6.1 GHz), whereas for LP, the bandwidth has two states about 300 MHz (5.7-6 GHz) and 600 MHz (5.3-5.9 GHz). This reconfigurable patch antenna with agile polarization and frequency diversity has good performance and concise structure, which can be also used for LP at 2.6-GHz Worldwide Interoperability for Microwave Access (WiMAX), digital multimedia broadcasting, 3.5-GHz WiMAX, C-band satellite (downlink), and HiperLAN/2 systems.