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Realizing Tunable Inverse and Normal Doppler Shifts in Reconfigurable RF Metamaterials.

Ran J, Zhang Y, Chen X, Fang K, Zhao J, Sun Y, Chen H - Sci Rep (2015)

Bottom Line: However, the inverse Doppler effect has never been observed on an electronically reconfigurable system with an external electromagnetic wave source at radio frequencies (RF) in experiment.Here we demonstrate an experimental observation of the inverse Doppler shift on an electronically reconfigurable RF metamaterial structure, which can exhibit anomalous dispersion, normal dispersion or a stop band, depending on an applied bias voltage.The effective velocity of this boundary and the resulting frequency shift can be tuned over a wide range by a digital switching circuit.

View Article: PubMed Central - PubMed

Affiliation: Tongji University, Shanghai, 200092, China.

ABSTRACT
The Doppler effect has well-established applications in astronomy, medicine, radar and metrology. Recently, a number of experimental demonstrations of the inverse Doppler effect have begun to appear. However, the inverse Doppler effect has never been observed on an electronically reconfigurable system with an external electromagnetic wave source at radio frequencies (RF) in experiment. Here we demonstrate an experimental observation of the inverse Doppler shift on an electronically reconfigurable RF metamaterial structure, which can exhibit anomalous dispersion, normal dispersion or a stop band, depending on an applied bias voltage. Either inverse or normal Doppler shift is realized by injecting an external RF signal into the electronically reconfigurable metamaterial, on which an electronically controllable moving reflective boundary is formed. The effective velocity of this boundary and the resulting frequency shift can be tuned over a wide range by a digital switching circuit. This work is expected to open up possibilities in applying the inverse Doppler effect in wireless communications, radar and satellite navigation.

No MeSH data available.


Related in: MedlinePlus

The voltage-dependent transmission characteristics.a, Theoretical dispersion curves under different bias voltages. The gray plane indicates the working frequency 1 GHz, while the red, green and dark curves correspond to three typical bias voltages (6 V, 11 V and 24 V). b, Simulated /S21/ under different bias voltages. The branch above is the right-handed passband while the branch blow is the left-handed passband. The dark diamond markers are a set of bias voltages (5 V, 11 V and 23 V) at 1 GHz for achieving the equivalent transmission characteristics in a. c, Measured /S21/ verse frequency at the three bias voltages shown in a.
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f2: The voltage-dependent transmission characteristics.a, Theoretical dispersion curves under different bias voltages. The gray plane indicates the working frequency 1 GHz, while the red, green and dark curves correspond to three typical bias voltages (6 V, 11 V and 24 V). b, Simulated /S21/ under different bias voltages. The branch above is the right-handed passband while the branch blow is the left-handed passband. The dark diamond markers are a set of bias voltages (5 V, 11 V and 23 V) at 1 GHz for achieving the equivalent transmission characteristics in a. c, Measured /S21/ verse frequency at the three bias voltages shown in a.

Mentions: Figure 2a shows the theoretical dispersion curves of the CRLH TL as a function of the bias voltages which are calculated by considering the transmission line as a cascade network (see Supplementary Information S-II). The gray plane at 1 GHz cuts across the upper branches (right-handed passband), the band gap, and the lower branches (left-handed passband) of the dispersion curves under different bias voltages. The red, green and dark curves correspond to the dispersion under bias voltages of 6 V, 11 V and 24 V, respectively. Figure 2b shows the simulated transmission, in terms of /S21/, under different bias voltages. Because of inaccuracy of the varactor circuit model in ADS, the bias voltages in simulation needed to be set slight differently from those in the theoretical model, i.e. 5 V, 11 V and 23 V for achieving the equivalent transmission characteristics (as shown in Supplementary Fig. 7b). Both figures indicate that with the increased bias voltages, the propagation characteristics at 1 GHz change from right-handed transmission to a band gap (stop-band transmission), and then to left-handed transmission. The measured transmission /S21/ at 1 GHz at three voltages of 6 V, 11 V and 24 V is illustrated in Fig. 2c.


Realizing Tunable Inverse and Normal Doppler Shifts in Reconfigurable RF Metamaterials.

Ran J, Zhang Y, Chen X, Fang K, Zhao J, Sun Y, Chen H - Sci Rep (2015)

The voltage-dependent transmission characteristics.a, Theoretical dispersion curves under different bias voltages. The gray plane indicates the working frequency 1 GHz, while the red, green and dark curves correspond to three typical bias voltages (6 V, 11 V and 24 V). b, Simulated /S21/ under different bias voltages. The branch above is the right-handed passband while the branch blow is the left-handed passband. The dark diamond markers are a set of bias voltages (5 V, 11 V and 23 V) at 1 GHz for achieving the equivalent transmission characteristics in a. c, Measured /S21/ verse frequency at the three bias voltages shown in a.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4481520&req=5

f2: The voltage-dependent transmission characteristics.a, Theoretical dispersion curves under different bias voltages. The gray plane indicates the working frequency 1 GHz, while the red, green and dark curves correspond to three typical bias voltages (6 V, 11 V and 24 V). b, Simulated /S21/ under different bias voltages. The branch above is the right-handed passband while the branch blow is the left-handed passband. The dark diamond markers are a set of bias voltages (5 V, 11 V and 23 V) at 1 GHz for achieving the equivalent transmission characteristics in a. c, Measured /S21/ verse frequency at the three bias voltages shown in a.
Mentions: Figure 2a shows the theoretical dispersion curves of the CRLH TL as a function of the bias voltages which are calculated by considering the transmission line as a cascade network (see Supplementary Information S-II). The gray plane at 1 GHz cuts across the upper branches (right-handed passband), the band gap, and the lower branches (left-handed passband) of the dispersion curves under different bias voltages. The red, green and dark curves correspond to the dispersion under bias voltages of 6 V, 11 V and 24 V, respectively. Figure 2b shows the simulated transmission, in terms of /S21/, under different bias voltages. Because of inaccuracy of the varactor circuit model in ADS, the bias voltages in simulation needed to be set slight differently from those in the theoretical model, i.e. 5 V, 11 V and 23 V for achieving the equivalent transmission characteristics (as shown in Supplementary Fig. 7b). Both figures indicate that with the increased bias voltages, the propagation characteristics at 1 GHz change from right-handed transmission to a band gap (stop-band transmission), and then to left-handed transmission. The measured transmission /S21/ at 1 GHz at three voltages of 6 V, 11 V and 24 V is illustrated in Fig. 2c.

Bottom Line: However, the inverse Doppler effect has never been observed on an electronically reconfigurable system with an external electromagnetic wave source at radio frequencies (RF) in experiment.Here we demonstrate an experimental observation of the inverse Doppler shift on an electronically reconfigurable RF metamaterial structure, which can exhibit anomalous dispersion, normal dispersion or a stop band, depending on an applied bias voltage.The effective velocity of this boundary and the resulting frequency shift can be tuned over a wide range by a digital switching circuit.

View Article: PubMed Central - PubMed

Affiliation: Tongji University, Shanghai, 200092, China.

ABSTRACT
The Doppler effect has well-established applications in astronomy, medicine, radar and metrology. Recently, a number of experimental demonstrations of the inverse Doppler effect have begun to appear. However, the inverse Doppler effect has never been observed on an electronically reconfigurable system with an external electromagnetic wave source at radio frequencies (RF) in experiment. Here we demonstrate an experimental observation of the inverse Doppler shift on an electronically reconfigurable RF metamaterial structure, which can exhibit anomalous dispersion, normal dispersion or a stop band, depending on an applied bias voltage. Either inverse or normal Doppler shift is realized by injecting an external RF signal into the electronically reconfigurable metamaterial, on which an electronically controllable moving reflective boundary is formed. The effective velocity of this boundary and the resulting frequency shift can be tuned over a wide range by a digital switching circuit. This work is expected to open up possibilities in applying the inverse Doppler effect in wireless communications, radar and satellite navigation.

No MeSH data available.


Related in: MedlinePlus