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Figure 1 shows the two common topologies of SRR Structures and their equivalent circuit model. [...]a new element is intruduced by etching the negative image of SRRs in the ground plane or the radiating element and this is known as the Complementary Split Ring Resonator (CSRR) as shown in Figure 2. The addition of extra bands by the split ring SC-SRR is due the presence of the inductance and capacitance, which are the primary parameters in the resonance frequency created by the split ring. 2.4.Microstrip Antenna with DC-CSRR By adding another ring to the first one in Figure 5, the frequency bands shift to the lower frequencies, thereby maintaining the bands in Figure 4 but slightly shifted to the left side. [...]with the insertion of the double rings, the frequencies produced are 2.99, 3.57 and 5.14 GHz. Antenna miniaturization and multiband are both achieved by the influence of DC-CSRR. [...]the application of DC-CSRR is not limited to miniaturization or multiband as presented from the previous literature but to both in our design. Microstrip with SC-CSRR has shown better performance in terms of gain as shown in table 2. [...]a novel method to achieve miniaturization and multiband antenna using MCSRR is hereby presented.

This paper presents a novel single-layer dual band-rejection-filter based on Spoof Surface Plasmon Polaritons (SSPPs). The filter consists of an SSPP-based transmission line, as well as six coupled circular ring resonators (CCRRs) etched among ground planes of the center corrugated strip. These resonators are excited by electric-field of the SSPP structure. The added ground on both sides of the strip yields tighter electromagnetic fields and improves the filter performance at lower frequencies. By removing flaring ground in comparison to prevalent SSPP-based constructions, the total size of the filter is significantly decreased, and mode conversion efficiency at the transition from co-planar waveguide (CPW) to the SSPP line is increased. The proposed filter possesses tunable rejection bandwidth, wide stop bands, and a variety of different parameters to adjust the forbidden bands and the filter’s cut-off frequency. To demonstrate the filter tunability, the effect of different elements like number (n), width (WR), radius (RR) of CCRRs, and their distance to the SSPP line (yR) are surveyed. Two forbidden bands, located in the X and K bands, are 8.6–11.2 GHz and 20–21.8 GHz. As the proof-of-concept, the proposed filter was fabricated, and a good agreement between the simulation and experiment results was achieved.

This paper delves into the intricacies of designing, fabricating, and characterizing a metasurface exhibiting epsilon-negative (ENG) and near-zero index (NZI) properties. Specifically, it focuses on an eye-shaped coupled circular split ring resonator (CC-SRR) metasurface, crafted from copper on an epoxy resin fiber (FR-4) dielectric substrate material. The design is further optimized to induce resonance frequencies at approximately 7.5, 8.8, and 13.4 GHz within the C, X, and Ku bands, respectively. Utilizing the COMSOL Multiphysics and CST Microwave Studio simulation tools, the structural design is developed to ascertain its electromagnetic properties across the 1–15 GHz frequency spectrum. Experimental measurements of the transmission characteristics of the fabricated metasurface align closely with the simulated results. The electromagnetic field distributions of the proposed metasurface structure are scrutinized, revealing tunable characteristics contingent upon variations in the thickness ( t s ) of the dielectric substrate material and the copper resonator thickness ( t m ). Additionally, a theoretical model employing an equivalent circuit, featuring various inductor (L) and capacitor (C) components, is presented to compare against simulated results for the targeted resonance frequencies.

Indonesia had a total of 19.47 million individuals diagnosed with diabetes in 2021, the fifth position globally, as reported by the International Diabetes Federation (IDF). Diabetes requires periodic medical examinations, yet many individuals are hesitant to utilize invasive medical devices. The ring slot circular resonator (RSCR) inspired this sensor’s design. Non-invasive glucose measurement was done with flexible 2.45 GHz sensors. The reflection coefficient (S11) simulation result is -20.76 dB at 2.458 GHz and 894.8 MHz bandwidth. Saliva samples obtained from 20 individuals were subjected to 20 separate tests. Before collecting saliva samples, the volunteers’ blood sugar levels were assessed. Research indicates that the appropriate frequency range for average blood sugar levels (less than 125 mg/dl) is 1.55 GHz to 2.16 GHz, while diabetes patients with blood glucose levels (BGL) above 125 mg/dl had frequencies above 2.3 GHz. Test results show a positive correlation between glucose level and testing frequency. In addition to blood samples, saliva samples can serve as alternate specimens for assessing an individual’s BGL.

In this research work, a symmetrical four-capacitance loaded complementary circular split ring resonator is proposed, which uses an ultra-thin Zinc Selenide (ZnSe) substrate to realize a low-profile triple-band metamaterial (MTM) perfect absorber for application in the terahertz (THz) frequency range. The electromagnetic properties of the proposed structure were calculated and investigated using the Finite Integration Technique (FIT). The proposed structure exhibited three highly absorptive (nearly perfect) peaks at the resonance frequencies of 15.68 THz, 37.48 THz, and 39.55 THz. Furthermore, the absorber was found to be insensitive to the polarization and incident wave angles, due to its symmetrical design. The effects of the conductor type, substrate thickness, unit cell dimension, resonator gap, and substrate type on the reflection and absorption spectra were investigated. To validate the numerical results, the proposed design was analyzed using High-Frequency Simulation Software (HFSS) and Advanced Design System (ADS). The surface current, electric field, and magnetic field distributions at the three-resonance frequency were analyzed. It was concluded that the overall performance of the proposed MTM structure was superior compared to those reported in the literature. The proposed design could be a good candidate for application in stealth technology, imaging, and thermal energy harvesting.

In this article, an antenna array with suppressed side lobe level (SLL) is proposed for a 5G mm-wave base station application by employing a circular complementary split ring resonator (CCSRR) and amplitude tapering technique. The single, double, and hybrid CCSRRs are etched on the ground plane of the array to minimize the side-lobe power. The proposed technique suppresses pre-main beam power level and post-main beam power level by an amount of 20.08 dB and 27.28 dB, respectively. Further, a typical Dolph–Chebyscheff weighted low side lobe level array is compared with the suggested CCSRRs couplets loading. The presented module is fabricated and experimentally validated and it has a better agreement between the simulated and measured response. The presented array module has a low profile and it is very simple to integrate with other RF circuits located on the PCB board. In addition, the proposed array has wider impedance bandwidth with a low side lobe power level than the other CCSRR arrangement. Among the three configurations, hybrid CCSRR has wider beam width, enhanced gain and improved side-lobe suppression than all other CCSRR arrangement. Thus, the hybrid CCSRR configuration is a good candidate to employ 5G mm-wave indoor applications, 5G mm-wave mobile base station, K a -band based medium distance modern wireless communication.

This article presents the design and analysis of conformal circular monopole antenna with split ring resonator to get frequency notch characteristics in the wideband. Split ring resonators placed on one side of the substrate and complementary split ring resonators placed on the other side of the substrate at defected ground structure, which yields the frequency notch characteristics with respect to the microstrip feeding. Dual notch band characteristics are obtained between 4–4.3 and 7.3–8.1 GHz. The analyzed conformal characteristic of the antenna supports excellent constant reflection coefficient characteristics over the band at different angles. The impedance and radiation characteristics of the antenna model is analysed in simulation along with unit cell analysis of the SRR and the measured results are providing good agreement with them.

This article presents a dual-band circularly polarized hybrid ring CDRA (Cylindrical dielectric resonator antenna) for wireless applications in C and X-band. A circular ring inclusive of a slotted cross-shaped microstrip feed line is used to excite the ring CDRA and generation of HEM 11δ and TEM 01δ modes. Multiple inverted Z-shaped apertures and circular ring along with a slotted cross-shaped microstrip feed line are responsible for the generated circular polarization wave between 3.92 and 4.08 GHz in lower band and 8.85 to 9.61 GHz in upper band with 4% (160 MHz) and 8.23% (760 MHz) axial ratio bandwidth (ARBW) respectively. The proposed antenna also offers impedance bandwidth of 20.58% (780 MHz) between 3.40 and 4.18 GHz in lower band while 29.31% (2490 MHz) between 7.25 and 9.74 GHz in upper band resonating at 3.73 and 7.79 GHz with − 26.4 and − 35.61 dB return loss respectively. The proposed ring CDRA shows stable gain of peak value 5.8 dB (simulated) and 5.8 dB (measured) in lower band while 7.7 dB (simulated) and 8.2 dB (measured) in upper band.

In this article, a dual-sense triband circularly polarized modified slot antenna loaded with metamaterial structures such as split-ring resonator and cross strips is proposed. The first resonant frequency is generated using the modified square slot which produces the two degenerative modes required to achieve circular polarization (CP). The corners of slot antenna are extended to obtain the orthogonal modes. The second resonant band is obtained using the single split-ring resonator. Two micro-splits in Split Ring Resonator (SRR) orthogonal to each other produces CP due to electric field generated by the micro-splits. The third resonance band is obtained due to loading of cross strips. The orthogonal phase is adjusted by varying the length of cross strips, so that the CP is achieved. All resonance bands are tuned independently. The measured impedance bandwidth of 31.68%, 4.55%, and 8.6% is obtained in first, second, and third bands respectively. The axial ratio bandwidth of 13.04%, 2.7%, 8.6% and peak gain of 3.8 dBic, 3.9 dBic, 3.7 dBic are obtained respectively. The simulated radiation efficiencies of above 80% is achieved in all bands. The left-hand CP is obtained in first two band as co-polarization and right-hand CP is obtained at the third band as co-polarization with respect to cross-polarization radiation. The cross-polarization of minimum −10 dB is obtained in all three bands. The proposed design is well suitable for the Bluetooth, n78 and n79 5G applications.

A new compact broadband circularly polarized (CP) crossed dipole antenna using split ring resonator (SRR) and parasitic patches are presented. The proposed antenna is mainly composed of two orthogonal strip dipoles, two 90∘ phase delay lines, four SRRs, and four parasitic patches. The combination of the orthogonal strip dipoles and the delay lines forms a crossed dipole as the main CP radiator. The well-designed SRR can extend the current path and improve the current distribution of high-frequency without increasing the size of the antenna, thereby reducing the size of the antenna and increasing the axial ratio (AR) bandwidth of the high-frequency. The introduction of parasitic patches can improve the current distribution between the upper and lower cut-off frequency points of the bandwidth, and make up for the defects of the insufficient bandwidth of the crossed dipole and the SRR, thereby realizing broadband CP radiation. To verify the antenna, a physical prototype is fabricated. The measured results show that the impedance bandwidth (IBW) of 69.1% (1.38-2.84 GHz), and a wide AR bandwidth of 57.7% (1.43-2.59 GHz). In addition, the designed antenna achieves a stable gain in the working band and a certain band-edge selectivity. Such a single-fed, simple structure and the wideband CP antenna is an excellent candidate for communication systems such as ISM (2.4 GHz), WiBro (2.3-2.39 GHz)and Inmarsat.