Combination Of Split Ring Resonators Research Articles

Dynamic bifunctional THz metasurface via dual-mode decoupling

Metasurfaces have powerful light field manipulation capabilities and have been researched and developed extensively in various fields. With an increasing demand for diverse functionalities, terahertz (THz) metasurfaces are also expanding their domain. In particular, integrating different functionalities into a single device is a compelling domain in metasurfaces. In this work, we demonstrate a functionally decoupled THz metasurface that can incorporate any two functions into one metasurface and switch dynamically through external excitation. This proposed metasurface is formed by the combination of split-ring resonators and phase change material vanadium dioxide ( VO 2 ). It operates in the single-ring resonant mode and double-ring resonant mode with varying VO 2 in insulating and metallic states, respectively. More importantly, the phase modulation is independent in two operating modes, and both cover a 360° cross-polarized phase with efficient polarization conversion. This characteristic makes it obtain arbitrary independent phase information on the metasurface with different modes to switch dual functions dynamically. Here, we experimentally demonstrate the functions of a tunable focal length and large-angle focus deflection of a THz off-axis parabolic mirror to verify the dual-function switching characteristics of the functionally decoupled metasurface. The functionally decoupled metasurface developed in this work broadens the way for the research and application of multifunctional modulation devices in the THz band.

The Impact of Structural Parameters of Split-Ring Resonators on the Terahertz Radiation Characteristics of Micro-Structured Photoconductive Antennas: A Simulation Study

In this study, we have theoretically designed a micro-structured photoconductive antenna based on the combination of split-ring resonator (SRR) and dipole photoconductive antenna. Further, we have used numerical simulations to prove that the proposed antenna can enhance the terahertz radiation characteristics. According to the equivalent circuit model analysis, the terahertz radiation power and the resonance frequency of this antenna were found to be closely related with the structural parameters of the SRR. A numerical model was established to simulate the effect of the structural parameters of SRR on the terahertz radiation characteristics of the proposed antenna. The results indicated that an increase in the width and length of SRR caused an increase in the peak power intensity and a decrease in the resonance frequency. Moreover, as the gap width of SRR was increased, the peak power intensity was decreased and the resonance frequency was increased. Furthermore, the terahertz radiation power increased with increase in the gap width of antennas. Overall, we show that high-power terahertz radiation sources with specific frequency can be obtained by optimizing the structural parameters of SRR, and such sources are potentially useful in a variety of fields such as biomedicine, material analysis, and detection systems.

A low rcs compact circularly polarized dual band slot antenna loaded with SRR and CSRR for satellite applications

ABSTRACT In this work, a low radar cross-section (RCS) dual-band with one band circularly polarised (CP) slot antenna consisting of an L-shaped metallic strip along with a combination of Split Ring Resonator (SRR) and complementary SRR (CSRR) is proposed. In the dual-band, one wideband operation is obtained by creating a wide slot in the ground plane of the antenna and a narrow band is achieved by loading the antenna with a combination of SRR-CSRR. The proposed antenna achieves impedance bandwidth of 1.5 to 3.26 GHz and 3.6 to 4.1 GHz. The proposed design has 3-dB axial ratio bandwidth (ARBW) of 2.5 to 3 GHz and the peak gain of the antenna is 4.2 and 3.3 dBi in the respective bands. The proposed antenna exhibits significant RCS reduction in the wideband of 4.7 to 18 GHz and peak RCS reduction of 26 dB is achieved at 11.3 GHz. Also, the sense of polarisation of the proposed antenna can be changed by 90° rotating the L-shaped metallic strip with reference to the slot in the ground plane.

Design Dual-Polarization Frequency Selective Rasorber Using Split Ring Resonators

A novel dual-polarization frequency selective rasorber with one transmission band and two absorbing bands is proposed in this paper. The structure is composed of a lossless frequency selective surface layer and a resistive layer. The resistive layer is a combination of split ring resonators and Jerusalem crosses. The frequency selective surface layer is a combination of grids and square rings. Split ring resonators are used to generate parallel resonances in this paper. When the parallel resonant frequency of the split ring resonators and that of the frequency selective surface layer are the same, a passband is obtained. Split ring resonators, Jerusalem crosses, and lumped resistors are used to create the absorbing bands. When surface current flows through two different paths on the split ring resonator, absorbing bands are obtained on each side of the passband. A frequency selective rasorber prototype is fabricated and measured to validate our design. The results show that the center frequency of the passband is 5.74 GHz, with an insertion loss of 0.25 dB. The lower and higher absorption bandwidths with absorption coefficient higher than 80% range from 1.92 to 3.73 GHz and from 7.41 to 9.34 GHz, respectively, and the reflection band with reflection coefficient less than -10 dB ranges from 1.96 to 9.32 GHz.

Penta-notched UWB antenna with sharp frequency edge selectivity using combination of SRR, CSRR, and DGS

This work presents penta-notched UWB antenna with sharp frequency edge selectivity using combination of SRR, CSRR, and DGS to reject the WiMAX (3.30–3.60 GHz), lower WLAN (5.150–5.350 GHz), upper WLAN (5.725–5.825 GHz), downlink of X-band satellite communication (7.0–7.40 GHz), and the uplink of X-band satellite communication (8.10–8.50 GHz) frequency bands. All these frequency bands lie within the UWB frequency spectrum. The proposed antenna is suitable for portable communication applications due to its compact dimensions. It sharply notches the existing frequency bands to mitigate the interference caused by nearby wireless communication systems within UWB frequency range. The sharp notching is achieved by the combination of complementary split ring resonators (CSRR) on the radiating semi-circular patch, split ring resonators (SRR) placed at the junction of the feedline, and a pair of defected ground structures (DGS). All notched bands can be well controlled and shifted and the equivalent lumped model of the notched bands are also developed for validation. The proposed antenna simulated, and measured results show better performance over the present state-of-the-art designs. The proposed penta-notched UWB antenna possesses better reflection coefficient, VSWR, stable gain, and small foot print. The proposed antenna has a nearly omnidirectional radiation pattern in the passbands.

Miniaturized dual-band antenna array with double-negative (DNG) metamaterial for wireless applications

A miniaturized dual-band antenna array using a negative index metamaterial is presented for WiMAX, LTE, and WLAN applications. This left-handed metamaterial plane is located behind the antenna array, and its unit cell is a combination of split-ring resonator, square electric ring resonator, and rectangular electrical coupled resonator. This enables the achievement of a metamaterial structure exhibiting both negative permittivity and permeability, which results in antenna size miniaturization, efficiency, and gain enhancement. Moreover, the proposed metamaterial antenna has realized dual-band operating frequencies compared to a single frequency for normal antenna. The measured reflection coefficient (S11) shows a 50.25% bandwidth in the lower band (from 2.119 to 3.058 GHz) and 4.27% in the upper band (from 5.058 to 5.276 GHz). Radiation efficiency obtained in the lower and upper band are >95 and 80%, respectively.

Left Handed Microstrip Transmission Line Loaded with Combination of Split Ring Resonator and Complementary-SRR

An approach to realize left-handedness in microstrip transmission line by simultaneously loading it with split ring resonator and complementary split ring resonator is proposed. A transmission line individually loaded with either with SRR (−μ) or CSRR (−ε) has band rejection but when simultaneously loaded has a passband near the previously rejected band due to negative values of both −μ and −ε. i.e., left handedness. The design is compact, low profile and independent of the substrate permittivity. Simulation and experimental results are also presented and the design is suitable for devices like filters and couplers.

Influence of split ring resonators on the properties of propagating structures

The study of a 50 V microstrip line and microstrip resonators loaded with resonant elements called split-ring resonators (SRRs) is presented. The two different filtering phenomena observed lead to make an analogy with those observed when waveguides are loaded with these elements. So, in order to make this analogy, the different results obtained with the SRRs loaded in a propagating and an under cut-off waveguide are shown. Then, another technique to achieve and even improve these results is presented. The technique consists of using, respectively, a 50 V microstrip line and capacitive-gap-coupled microstrip resonators instead of the propagating and under cut-off waveguides. The numerical and experimental results obtained with the two structures (waveguides and microstrip lines) are compared and discussed. This study shows that the combination of SRRs with guiding structures helps in the design of compact structures, but an enhancement of the performances needs a better fabrication accuracy.