Design of triangular shaped slotted patch antennas for both wideband and multiband applications

In this article two fractal geometry-based slotted patch antennas are designed to achieve wideband response with multiband characteristics and reduced cross polarized radiation in both E- and H-plane for all the resonating bands. The proposed antennas are fed with microstrip line feeding formed on a FR4 substrate of size 0.25𝜆0 × 0.25𝜆0 × 0.02𝜆0 mm3 and loaded with a partial ground plane at the bottom of the substrate. HFSS is used to design and simulate both the antennas. Wideband behavior and impedance matching of Antenna-1 are improved by optimizing the factor of iteration and length of the ground plane. Due to addition of 3 identical split ring resonators (SRR) with the antenna geometry leads to achieve multiband response in Antenna-2. The dimensions of the SRR connectors and feedline have been optimized through parametric analysis to match the impedance properly at all the three resonating bands. It has been found that simulated and measurement results of both the antennas are properly matched.

Design and implementation of compact tri- and quad-band SIW power divider using modified circular complementary split-ring resonators

This paper presents a miniaturized tri- and quad-band power divider (PD)based on substrate integrated waveguide (SIW). By adopting different types of modified circular complementary split-ring resonators on the top surface of SIW, multiple passbands are generated propagating below the SIW cut-off frequency. The working principle is based on evanescent mode propagation that decreases the operating frequency of the PD and helps in the miniaturization of the proposed structure. The operating frequency of the proposed PD can be individually controlled by changing the dimensions of the resonator. To verify the proposed concept, a tri-band and a quad-band PD exhibiting 3 dB equal power division at 2.41/3.46/4.65 GHz and 2.42/3.78/4.74/5.8 GHz are designed using the full-wave simulator, validated through circuit model, fabricated and experimentally verified. The measured results agree well with the simulations. The proposed PDs have good performance in terms of reasonable insertion loss, isolation, minimum amplitude and phase imbalance, smaller footprint, easy fabrication and integration. The size of the fabricated prototype is 18.3 mm × 8.4 mm, which corresponds to 0.205λ g × 0.094λ g , λ g being the guided wavelength at the first operating frequency.

Two-Channel VO2 Memory Meta-Device for Terahertz Waves

Vanadium oxide (VO2), as one of the classical strongly correlated oxides with a reversible and sharp insulator-metal transition (IMT), enables many applications in dynamic terahertz (THz) wave control. Recently, due to the inherent phase transition hysteresis feature, VO2 has shown favorable application prospects in memory-related devices once combined with metamaterials or metasurfaces. However, to date, VO2-based memory meta-devices are usually in a single-channel read/write mode, which limits their storage capacity and speed. In this paper, we propose a reconfigurable meta-memory based on VO2, which favors a two-channel read/write mode. Our design consists of a pair of large and small split-ring resonators, and the corresponding VO2 patterns are embedded in the gap locations. By controlling the external power supply, the two operation bands can be controlled independently to achieve at least four amplitude states, including “00”, “01”, “10”, and “11”, which results in a two-channel storage function. In addition, our research may provide prospective applications in fields such as THz switching, photon storage, and THz communication systems in the future.

Broadband selection of EHF radiation of metamaterial surface obtained by photolithography

In paper results of research of metamaterial surface based on split-ring resonators obtained by photolithography are presented. Numerical simulation of electromagnetic response of the created structure are shown. Experimental researches of the transmission coefficient using quasi-optical methods of continuous and time-domain spectroscopy in the frequency range from 34 to 200 GHz were carried out. Area of broadband screening in the EHF range has been found.

E-Textile Metamaterials: Stop Band Pass Filter

In this paper, the utilization of common fabrics for the manufacturing of e-textile metamaterial is investigated. The proposed design is based on a transmission line loaded with split-ring resonators (SRRs) on a cotton substrate for filter signal application. The proposed design provides a stop band between 2.7 GHz and 4.7 GHz, considering a four stage SRR topology. Experimental results showed stop band levels higher than −30 dB for the proposed compact embroidered metamaterial e-textiles. The validated results confirmed embroidery as a useful technique to obtain customized electromagnetic filter properties, such as transmitted signal filtering and control, on wearable tech device applications.

Magnetic excitation of high-Q resonance with split-ring resonators

Planar split-ring resonators (SRRs) with broken symmetry, excited by the electric field of incident wave, have been widely used to realize the high-Q resonance. In this paper, we report by theory and experiment an alternative scheme to induce the SRR-based high-Q resonance. The proposed scheme utilizes a two-dimensional array of vertical SRRs with vertical air gaps, which enables the excitation of narrow resonance with magnetic field and strong enhancement of local electromagnetic fields. The working mechanism correlates with the strong directional dependence of the dipole radiation (i.e., the elimination of electric-dipole radiation of the SRRs in the propagation direction), rather than the destructive interference due to the structural symmetry breaking. The dependence of Q factor on the structural parameters has also been studied theoretically, suggesting that a Q factor more than 2000 can be achieved. The results may be useful for designing narrow-band filters and sensors in the microwave or THz regime.

Observation of optical gyromagnetic properties in a magneto-plasmonic metamaterial

Metamaterials with artificial optical properties have attracted significant research interest. In particular, artificial magnetic resonances in non-unity permeability tensor at optical frequencies in metamaterials have been reported. However, only non-unity diagonal elements of the permeability tensor have been demonstrated to date. A gyromagnetic permeability tensor with non-zero off-diagonal elements has not been observed at the optical frequencies. Here we report the observation of gyromagnetic properties in the near-infrared wavelength range in a magneto-plasmonic metamaterial. The non-zero off-diagonal permeability tensor element causes the transverse magneto-optical Kerr effect (TMOKE) under s-polarized incidence that otherwise vanishes if the permeability tensor is not gyromagnetic. By retrieving the permeability tensor elements from reflection, transmission, and TMOKE spectra, we show that the effective off-diagonal permeability tensor elements reach the 10-3 level at the resonance wavelength (~900 nm) of the split-ring resonators that is at least two orders of magnitude higher than that of magneto-optical materials at the same wavelength. The artificial gyromagnetic permeability is attributed to the change in the local electric field direction modulated by the split-ring resonators. Our study demonstrates the possibility of engineering the permeability and permittivity tensors in metamaterials at arbitrary frequencies, thereby promising a variety of applications of next-generation nonreciprocal photonic devices, magneto-plasmonic sensors, and active metamaterials.