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.