Key Lab of MOI, ZJU 2Department of Optical Engineering, ZJU
Introduction
Results
Over the past several years, artificial magnetic conductor (AMC) has attracted much attention due to its ability in suppressing the surface wave and realizing the low-profile antennas. The main drawback of AMC ground plane is its relatively narrow bandwidth compared to the ultra-wide bandwidth (UWB) antenna. Recently, tunable THz devices based on graphene are successfully developed by using the variable surface conductivity of graphene under different applied voltages. In our work, the tunablity of graphene-based AMC is proposed and demonstrated. By varying the chemical potential, the equivalent capacitance of the graphene-based AMC can be dramatically tuned, and the resonance frequency shifts subsequently.
Reflection Phase (deg)
200
0 c=0.4 eV
100
Reflection Magnitude (dB)
1State
1 Wang ,
c=0.5 eV c=0.6 eV c=0.8 eV
0
c=1 eV
-100
-200
1
2
3
4
-5 c=0.4 eV
0
c=0.5 eV c=0.6 eV
-10
-2
c=0.8 eV
-4
c=1 eV
-15
-6 2.0
0
1
Frequency (THz)
2
2.5
3.0
3
4
Frequency (THz)
(a) (b) Figure 3: The reflection of the graphene-based AMC with different chemical potentials. (a) Phase; (b) Magnitude.
Model
(a)
(b)
Figure 1: (a) Schematic of the AMC unit, and (b) its equivalent circuit model.
• The reflection phase R for graphene-based AMC with square patches is 𝑍𝑠 − 𝜂0 𝑅= 𝑍𝑠 + 𝜂0 Zs is the total surface impedance, which can be calculated by −1 1 1 𝑍𝑠 = + 𝑍𝑑 𝑍𝑔
where Zd and Zg are the impedances of grounded substrate and patch array, respectively. 𝜂0 𝑍𝑑 = 𝑗 tan 𝑘𝑑 𝑡 = 𝑗𝜔𝐿𝑑 𝜔 𝜀𝑟 𝐷 𝜔𝜏 1 1 𝜔𝜏≫1 𝑍𝑔 =𝑗 − = 𝐷 − 𝑔 𝜎0 𝜇𝑐 𝜔𝐶𝑒𝑓𝑓 𝑗𝜔𝐶𝑔 𝜔 𝑒2 𝑘𝐵 𝑇𝜏 𝜇𝑐 −𝜇𝑐 𝑘𝐵 𝑇 𝜎0 𝜇𝑐 = + 2ln 1 + 𝑒 2 𝑘𝐵 𝑇 𝜋ℏ
(c) (d) Figure 4: Parametric study of graphene-based AMC with (a) D, (b) g, (c) t, and (d) εr, respectively.
(a) 800
k d
ε(a) r, μ Substrate Ground
Reflection Phase (deg)
f (GHz)
200
q
400
200
100
0
0
-100
-200 0.0
μc=1 eV
600
Simulation Graphene Patch
(b)
1.0
1.5
2.0
A
1 C M
A
2 C M
A
3 C M
(c)
(d) Figure 5: (a)-(c) The reflection phases of graphene-based AMC with different geometric shapes, and (d) comparison of frequency range ∆f.
Simulation Analytical results (b) c=1 eV 0.5
are u Sq M C A
2.5
3.0
3.5
Frequency (THz)
Figure 2: (a)Schematic view and of graphene-based AMC; (b) Comparison between analytical and simulated results for graphene-based AMC with square patches.
4.0
Conclusions In our work, a tunable graphene-based AMC is proposed and demonstrated. Parametric study is conducted to find the influence of the geometries on the AMC performance.
Study on Graphene â Based Antenna. Xuchen Wang. 1. , Wenyuan Li. 1,2 and Wensheng Zhao. 1. Introduction. Over the past several years, artificial magnetic ...
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