Optically Switched Frequency Reconfigurable Base Station Antenna for 5G Applications

Considering the defects of the commonly used electrically controlled microwave switches in reconfigurable antennas, an optically controlled microwave switch is designed, and based on this, an optically controlled microwave switch dualpolarisation frequency reconfigurable base station antenna is proposed. The antenna consists of two parts, a crossed dipole and a balun feed line, and two slits are cut in each dipole arm and connected with silicon wafers to achieve reconfigurable characteristics covering three operating frequency bands for 5G. The overall size of the antenna is $40 \mathrm{~mm} \times 40 \mathrm{~mm} \times 18.6 \mathrm{~mm}$, and the electrical dimensions calculated at 2.6 GHz are $0.35 \lambda \times 0.35 \lambda$ $\times 0.16 \lambda$. Electromagnetic simulation results show that the impedance bandwidths of the antenna for the three operating states with $\mathrm{S}_{11}{\lt }-10 \mathrm{~dB}$ are $\mathbf{2. 3 9 - 2. 7 6 G H z}, \mathbf{3. 1 8 - 3. 7 2 \mathrm {GHz}}$, and 4.79 5.19 GHz, respectively. In addition, the port isolation is not less than 25 dB and the cross-polarisation ratio in the main radiation direction is not less than 24 dB.