Wideband Full-Polarization Reconfigurable Antenna for Intelligent IoT Applications

novel wideband antenna with five reconfigurable polarization states is presented for intelligent IoT applications, where polarization agility can be exploited by a higher-layer controller to enhance link reliability in dynamic multipath environments. To achieve wideband performance across all polarization states, coupling mechanisms are strategically introduced into the radiation structure, feeding structure, and feeding network simultaneously. Firstly, through equivalent circuit analysis, shorting pins, metal strips, and slots are integrated into the radiation structure. The coupling mechanisms excite first- and second-order frequency responses, resulting in significant gain improvement and overlapping bandwidth enhancement. Secondly, a co-planar capacitive feeding structure is implemented into the feeding network to improve impedance matching. Subsequently, weakly coupled transmission lines are deployed within both differential and full-polarization feeding networks. Such a configuration ensures wide overlapping bandwidth performance throughout all five polarization states by suppressing phase shift errors. Finally, by controlling the ON/OFF states of PIN diodes, the feeding network generates desired phase differences, enabling the proposed antenna to be reconfigured between five polarization states, i.e., linearly polarization (LP) with three orientations, left-hand circularly polarization (LHCP), and right-hand circularly polarization (RHCP). Experimental results demonstrate that the antenna achieves an operating bandwidth of 8–13 GHz (47.6%), with axial ratio (AR) < 3.0 dB and in-band gain fluctuation < 3.0 dB. Characterized by wide bandwidth, full-polarization agility, and standard fabrication, the design presents a viable solution for demanding multi-polarization applications in industrial Internet of Things (IoT) scenarios.