Mutual Coupling mitigation of Terahertz antenna by using Graphene based metasurface

Mutual Coupling(MC) is an inevitable phenomenon for multiple antenna system. Due to the MC effect, the antenna suffers from a tradeoff between array performance and array size [1]. Different types of metasurface are reported... [ view full abstract ]

Mutual Coupling(MC) is an inevitable phenomenon for multiple antenna system. Due to the MC effect, the antenna suffers from a tradeoff between array performance and array size [1]. Different types of metasurface are reported in several literatures to reduce MC[2]. Realization of metasurface at the higher frequency is more difficult due to the losses in metal. In this regard, one of the promising materials in THz frequency is graphene[3].
In this paper, an efficient approach is reported to reduce mutual coupling between THz patch antenna arrays by incorporating a graphene metasurface designed on silicon wafer. A 50nm thick polysilicon layer and a 10nm thick SiO2 film are introduced on the top of the substrate successively. The polysilicon layer is used as a gate electrode. Due to the ultrathin thickness, the graphene has been modeled by surface conductivity. The value of surface conductivity is determined by Kubo’s formula [4]. Here, electric-field-coupled (ELC) resonator with extended arms is performed as a building block of the graphene metasurface. The extended arm of the ELC is used to bias the graphene properly. The unit cell analysis of graphene metasurface is shown in figure 1(a). The metasurface layer is designed to provide band-stop functionality at 0.47THz. In order to reduce coupling between the patches, a 2×7 array of proposed metasurface is implanted between two patches. It is observed in Figure 1(b) that 7dB isolation improvement is obtained. The H field distribution, shown in Figure 1(c), clearly exhibits the isolation between radiating elements in the proposed design. In addition, radiation pattern of the propose configuration does not degraded and also slight improvement in the cross polar performance has been obtained as shown in figure 1(d) .

Acknowledgment: The work funded by Visvesvaraya Young Faculty research fellowship award, under DeitY, Govt. of India.

Reference
[1]Z. Qamar, et. al., IEEE Trans. Ant. Propag. 7, 1653, (2016).
[2]D. Gangwar, et. al., Wireless Personal Communications, Springer. 75, 2747, (2014).
[3]G. Moreno, et. al., IEEE Ant. Wireless Propag. Letters. 15, 1533, (2016).
[4]G. W. Hanson, et. al., J. Appl. Phys. 103, 064302 (2008)