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Capacitive-coupled Series Spoof Surface Plasmon Polaritons.

Yin JY, Ren J, Zhang HC, Zhang Q, Cui TJ - Sci Rep (2016)

Bottom Line: Two conventional H-shaped unit cells are proposed to construct a new unit cell, and every two new unit cells are separated by a gap with certain distance, which is designed to implement capacitive coupling.It is shown that the proposed structure exhibits a stopband in 9-9.5 GHz while the band-pass feature maintains in 5-9 GHz and 9.5-11 GHz.The compact size, easy fabrication and good band-pass and band-stop features make the proposed structure a promising plasmonic device in SPP communication systems.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China.

ABSTRACT
A novel method to realize stopband within the operating frequency of spoof surface plasmon polaritons (SPPs) is presented. The stopband is introduced by a new kind of capacitive-coupled series spoof SPPs. Two conventional H-shaped unit cells are proposed to construct a new unit cell, and every two new unit cells are separated by a gap with certain distance, which is designed to implement capacitive coupling. The original surface impedance matching is disturbed by the capacitive coupling, leading to the stopband during the transmission of SPPs. The proposed method is verified by both numerical simulations and experiments, and the simulated and measured results have good agreements. It is shown that the proposed structure exhibits a stopband in 9-9.5 GHz while the band-pass feature maintains in 5-9 GHz and 9.5-11 GHz. In the passband, the reflection coefficient is less than -10 dB, and the transmission loss is around 3 dB; in the stopband, the reflection coefficient is -2 dB, and the transmission coefficient is less than -30 dB. The compact size, easy fabrication and good band-pass and band-stop features make the proposed structure a promising plasmonic device in SPP communication systems.

No MeSH data available.


Related in: MedlinePlus

Simulated transmission coefficients of the two coupling cases, as well as the detailed circuit model.
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f5: Simulated transmission coefficients of the two coupling cases, as well as the detailed circuit model.

Mentions: In order to verify the above conjectures that there is another pass band above the cutoff frequency of the new unit cell, the propagation characteristic is analyzed using the microwave network theory. Firstly, as shown in the schematic of the proposed capacitive coupled series spoof SPPs in Fig. 4(a), the equivalent circuit model can be simplified to a series circuit shown in Fig. 4(b). Here, each unit cell can be modeled as a transmission line with a characteristic impedance of Z0 in series with a capacitor C1, which signifies the capacitance response caused by the slot. The detailed calculation of the characteristic impedance Z0 can be found in ref. 31 and the value of the series capacitor C1 can be quantitative analyzed by some complicated co-simulation between CST Microwave Studio and Advanced Design System (ADS). Then we take one of the segments for calculation, and the transmission matrix can be deduced as:where ks is the wavenumber of spoof SPPs, P is the period of the unit cell. For clearance, the detailed circuit model is shown in Fig. 5. The dashed box means there are two kinds of coupled modes in the proposed transmission line, namely inductive coupling and capacitive coupling. When the H-shaped unit cell is set next to each other with no distance, it can be considered that there is an inductance, while the H-shaped unit cell is separated to the other with a certain distance, a capacitance can be assumed here. The capacitance C1 in Fig. 5 is the same one with that in the equation above. According to the detailed model, the transmission coefficients of two kinds of unit cells are simulated using ADS. The transmission coefficients of the two coupling cases are also shown in Fig. 5. With reference to the figure, it can be seen that for the inductive coupling, responding to the conventional SPP transmission lines, low-pass characteristic can be observed. This is consistent with the typical transmission characteristic of the SPP transmission lines in the open literatures. When the capacitive coupling is introduced to the transmission line, a stop band can be observed clearly. By change the width of the slot, the coupling capacitance can be changed, resulting in the frequency shifting of the stopband. This will be discussed latter. In brief, the simulated results can be applied to prove the validity of the proposed circuit model and the deduced equations based on it.


Capacitive-coupled Series Spoof Surface Plasmon Polaritons.

Yin JY, Ren J, Zhang HC, Zhang Q, Cui TJ - Sci Rep (2016)

Simulated transmission coefficients of the two coupling cases, as well as the detailed circuit model.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835726&req=5

f5: Simulated transmission coefficients of the two coupling cases, as well as the detailed circuit model.
Mentions: In order to verify the above conjectures that there is another pass band above the cutoff frequency of the new unit cell, the propagation characteristic is analyzed using the microwave network theory. Firstly, as shown in the schematic of the proposed capacitive coupled series spoof SPPs in Fig. 4(a), the equivalent circuit model can be simplified to a series circuit shown in Fig. 4(b). Here, each unit cell can be modeled as a transmission line with a characteristic impedance of Z0 in series with a capacitor C1, which signifies the capacitance response caused by the slot. The detailed calculation of the characteristic impedance Z0 can be found in ref. 31 and the value of the series capacitor C1 can be quantitative analyzed by some complicated co-simulation between CST Microwave Studio and Advanced Design System (ADS). Then we take one of the segments for calculation, and the transmission matrix can be deduced as:where ks is the wavenumber of spoof SPPs, P is the period of the unit cell. For clearance, the detailed circuit model is shown in Fig. 5. The dashed box means there are two kinds of coupled modes in the proposed transmission line, namely inductive coupling and capacitive coupling. When the H-shaped unit cell is set next to each other with no distance, it can be considered that there is an inductance, while the H-shaped unit cell is separated to the other with a certain distance, a capacitance can be assumed here. The capacitance C1 in Fig. 5 is the same one with that in the equation above. According to the detailed model, the transmission coefficients of two kinds of unit cells are simulated using ADS. The transmission coefficients of the two coupling cases are also shown in Fig. 5. With reference to the figure, it can be seen that for the inductive coupling, responding to the conventional SPP transmission lines, low-pass characteristic can be observed. This is consistent with the typical transmission characteristic of the SPP transmission lines in the open literatures. When the capacitive coupling is introduced to the transmission line, a stop band can be observed clearly. By change the width of the slot, the coupling capacitance can be changed, resulting in the frequency shifting of the stopband. This will be discussed latter. In brief, the simulated results can be applied to prove the validity of the proposed circuit model and the deduced equations based on it.

Bottom Line: Two conventional H-shaped unit cells are proposed to construct a new unit cell, and every two new unit cells are separated by a gap with certain distance, which is designed to implement capacitive coupling.It is shown that the proposed structure exhibits a stopband in 9-9.5 GHz while the band-pass feature maintains in 5-9 GHz and 9.5-11 GHz.The compact size, easy fabrication and good band-pass and band-stop features make the proposed structure a promising plasmonic device in SPP communication systems.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China.

ABSTRACT
A novel method to realize stopband within the operating frequency of spoof surface plasmon polaritons (SPPs) is presented. The stopband is introduced by a new kind of capacitive-coupled series spoof SPPs. Two conventional H-shaped unit cells are proposed to construct a new unit cell, and every two new unit cells are separated by a gap with certain distance, which is designed to implement capacitive coupling. The original surface impedance matching is disturbed by the capacitive coupling, leading to the stopband during the transmission of SPPs. The proposed method is verified by both numerical simulations and experiments, and the simulated and measured results have good agreements. It is shown that the proposed structure exhibits a stopband in 9-9.5 GHz while the band-pass feature maintains in 5-9 GHz and 9.5-11 GHz. In the passband, the reflection coefficient is less than -10 dB, and the transmission loss is around 3 dB; in the stopband, the reflection coefficient is -2 dB, and the transmission coefficient is less than -30 dB. The compact size, easy fabrication and good band-pass and band-stop features make the proposed structure a promising plasmonic device in SPP communication systems.

No MeSH data available.


Related in: MedlinePlus