Triangular Resonator Research Articles

High-Performance monolithic ceramic waveguide filter with isosceles Right-Angled triangular resonator for base station applications

This paper presents a high-performance integrated monolithic ceramic dielectric waveguide (DW) filter featuring isosceles right-angled triangular (IRAT) resonators. The fabrication process of the filter involves embedding a specific number of blind holes (BHs) or through holes/slots (THs/TSs) in a hexagonal ceramic dielectric block, fully metallizing the dielectric surface, and forming a monolithic ceramic DW filter. To achieve magnetic coupling, four THs and a BH are introduced in the oblique edges of two IRAT resonators; alternatively, a TS and BH are introduced in their right-angled edges. Electrical coupling is realized through a deep BH on the right-angle side of the resonators. Two non-adjacent resonators initiate weak cross-coupling by cascading a T-shaped rectangular TS, shallow BHs, and deep BH, creating two transmission zeros (TZs) outside the band. The filter was fabricated to ensure theoretical correctness and process reliability. The measured results show an insertion loss between 0.5 – 1 dB and a return loss greater than 18 dB at a bandwidth of 3.4 – 3.6 GHz. Two steep out-of-band TZs occur at 3.26 GHz and 3.72 GHz, aligning with simulation results. Therefore, the filter not only exhibits excellent performance but is also convenient for mass production and manufacturing, offering significant potential for future applications in 5G / 6G communication base stations.

Graphene-based tunable broadband metamaterial absorber for terahertz waves

In order to overcome the limitations exhibited by traditional absorbers in electromagnetic wave absorption, such as the extremely narrow absorption bandwidth and uncontrollable absorption results, this paper proposes a novel tunable broadband metamaterial absorber based on graphene. Compared to other terahertz absorbers, the absorber designed in this study exhibits simpler structural design, compact form, thin thickness, efficient absorption performance, and a broader bandwidth. This absorber adopts a three-layer structure, including a patterned monolayer graphene metasurface, a dielectric layer, and a metal substrate. The structure of this patterned graphene consists of four triangular graphene resonators, achieving both high absorption efficiency and maintaining an exceptionally wide absorption bandwidth. The simulation results indicate that at a Fermi energy level Ef of 0.45 eV, the absorber achieves a broadband absorption rate of over 90 % in the 3.287 THz to 5.247 THz frequency range under normal terahertz wave incidence conditions. By analyzing different quantities of the triangular graphene structure on the top of the absorber, we found that the wide absorption bandwidth of the absorber is mainly attributed to the structural coupling of the top-layer graphene in the absorber. Furthermore, through the study of electric field amplitude and current distribution, we stumbled upon that when terahertz waves are incident on the absorber, due to the structural coupling between the graphene layers, electric resonance and magnetic resonance occur within the absorber, resulting in the absorption effect. Finally, through the study of geometric parameters, different polarization angles and oblique incidence angles of the incident waves, as well as different Fermi energy levels of graphene, we discovered that by adjusting the Fermi energy level of graphene, the bandwidth and absorption performance of the absorber can be flexibly tuned. In addition, this absorber exhibits wide-angle absorption characteristics and polarization-insensitive properties, providing potential application prospects in fields such as terahertz thermal imaging and stealth technology.

Curvature-Adaptive Compact Triple-Band Metamaterial Uniplanar Compact Electromagnetic Bandgap-Based Printed Antenna for Wearable Wireless and Medical Body Area Network Applications

A novel, compact, monopole apple-shaped, triple-band metamaterial-printed wearable antenna backed by a uniplanar compact electromagnetic bandgap (UC-EBG) structure is introduced in this paper for wearable wireless and medical body area network (WBAN/MBAN) applications. A tri-band UC-EBG structure has been utilized as a ground plane to minimize the impact of antenna radiation on the human body and improve antenna performance for the proposed wearable antenna. Metamaterial triangular complementary split ring resonators (TCSRRs) are incorporated into the antenna and UC-EBG structure, resulting in a compact UC-EBG-backed antenna with an overall size of 39 × 39 × 2.84 mm3 (0.41 λg × 0.41 λg × 0.029 λg). The printed textile antenna operates at 2.45 GHz for the wireless local area network (WLAN), 3.5 GHz for 5G new radio (NR), and 5.8 GHz for the industrial, scientific, and medical (ISM) bands with improved gain and high-efficiency values. Furthermore, the performance of the antenna is analyzed on the human body, where three models of curved body parts are considered: a child’s arm (worst case) with a 40 mm radius, an adult’s arm with a 60 mm radius, and an adult’s leg with a 70 mm radius. The results demonstrate that the proposed antenna is an attractive candidate for wearable healthcare and fitness monitoring devices and other WBAN/MBAN applications due to its compact size, high performance, and low SAR values.

Resonance of vector vortex beams in a triangular optical cavity

We experimentally demonstrate resonance of first-order vector vortex beams (VVB) with a triangular optical cavity. We also show that, due to their symmetry properties, the VVBs commonly known as radial and azimuthal beams do not resonate at the same cavity length, which could be explored to use the triangular resonator as a mode sorter. In addition, an intracavity Pancharatnam phase shifter (PPS) is implemented in order to compensate for any birefringent phase that the cavity mirrors may introduce.

Fano resonance based on a triangular resonator and its application on nanosensing

Fano resonance sensors based on metal–insulator–metal (MIM) waveguide have potential applications in fields such as biology, chemistry, and the environment. Here, a nanosensor based on Fano resonance in an MIM-based isosceles triangular resonator system is proposed and numerically studied by finite element method. Simulation results show that the Fano peak can be easily tuned by adjusting the scale factor and the refractive index within the resonator. Furthermore, we thoroughly analyze the impact of the apex angle, rotation angle, and vertical displacement of the resonator on the transmission spectrum. Finally, the sensing characteristics of the proposed structure are optimized and analyzed, and a high-performance plasmonic sensor with a sensitivity of 1100[Formula: see text]nm/RIU and the maximum figure of merit of [Formula: see text] is obtained. The distinctive attributes of our suggested structure are applicable in the realization of various integrated components for the development of multifunctional high-performance nanophotonics devices.

Optimization of ultrathin polarization insensitive metamaterial absorbers using trust region algorithm based on Co-kriging model

In this paper, a trust region optimization algorithm integrated with a co-kriging surrogate-model is newly formulated to optimize compact ultrathin wideband metamaterial absorbers with high absorption. The reported algorithm is linked with the full vectorial finite element method to simulate and optimize the studied absorbers. In order to show the power of the suggested algorithm, the geometrical parameters of a previous metamaterial absorber (MA) with L-shaped resonators are optimized to achieve high absorption (over 90 %) over a frequency band from 13.8 GHz to 24.5 GHz covering most of KU and K bands. Then, a novel design of L-shaped MA with triangular resonators is optimized, analyzed and fabricated with high absorption (above 90 %) through a large frequency band from 11.9 GHz to 22 GHz covering the entire KU-band and most of the K-band. The reported design is also robust against the variations of the incident angle (above 80 % up to 50°) for both transverse electric (TE) and transverse magnetic (TM) polarized modes. Therefore, the proposed algorithm could be used efficiently for the design and optimization of metamaterial absorbers.

Development of a Balanced-to-Balanced Filtering Power Divider Based on Right-Angled Isosceles Triangular Patch Resonator

Development of a Balanced-to-Balanced Filtering Power Divider Based on Right-Angled Isosceles Triangular Patch Resonator

ENHANCING WEARABLE AND MEDICAL CONNECTIVITY: A NOVEL PRINTED TRIPLE-BAND METAMATERIAL ANTENNA FOR WBAN/MBAN APPLICATIONS

This paper presents a novel, compact, monopole apple-shaped, and triple-band metamaterial printed antenna for wireless body area network (WBAN) and medical body area network (MBAN) applications. The antenna is backed by a tri-band uniplanar compact electromagnetic bandgap (UC-EBG) structure that acts as a ground plane and incorporates metamaterial triangular complementary splitring resonators (TCSRRs). The proposed printed textile antenna operates at 2.45 GHz for wireless local area network (WLAN), 3.5 GHz for 5G new radio (NR), and 5.8 GHz for industrial, scientific, and medical bands. Implementing the UC-EBG structure resulted in a 99% decrease in the specific absorption rate (SAR) values over 1 g and 10 g of tissues and achieved gains of 5.45, 6.09, and 7.63 dBi at 2.45, 3.5, and 5.8 GHz, respectively. Due to its high performance, low SAR values, and compact size of 39 × 39 × 2.84 mm<sup>3</sup> (0.41 λ<sub>g</sub> × 0.41 λ<sub>g</sub> × 0.029 λ<sub>g</sub> ), the proposed antenna is an attractive candidate for wearable healthcare, fitness monitoring devices, and other WBAN/MBAN applications.

MEMS-Switched Triangular and U-Shaped Band-Stop Resonators for K-Band Operation.

Triangular resonators re-shaped into Sierpinski geometry and U-shaped resonators were designed, linking them with single-pole-double-through (SPDT) RF MEMS switches to provide frequency tuning for potential applications in the K-Band. Prototypes of band-stop narrowband filters working around 20 GHz and 26 GHz, interesting for RADAR and satellite communications, were studied in a coplanar waveguide (CPW) configuration, and the tuning was obtained by switching between two paths of the devices loaded with different resonators. As a result, dual-band operation or fine-tuning could be obtained depending on the choice of the resonator, acting as a building block. The studied filters belong to the more general group of devices inspired by a metamaterial design.

Triangular Sierpinski Microwave Band-Stop Resonators for K-Band Filtering.

Triangular resonators re-shaped with Sierpinski geometry were designed, manufactured, and tested for potential applications in the K-Band. Prototypes of band-stop filters working around 20 GHz and 26 GHz, interesting for RADAR and satellite communications, were studied in a coplanar waveguide (CPW) configuration. Single and coupled structures were analyzed to give evidence for: (i) the tuning of the resonance frequency by increasing the internal complexity of the triangle and (ii) resonance enhancement when coupled structures are considered. The exploited devices were part of the more extended family of metamaterial-inspired structures, and they were studied for their heuristic approach to the prediction of the spectrum using experimental results supported by electromagnetic simulations. As a result, a Sierpinski resonator, not only fed into but also fully embedded into a CPW environment, had a frequency response that was not easily determined by classical theoretical approaches.

Graphene based filter design using triangular patch resonator for THz applications

In this paper, graphene based tunable bandpass and bandstop filters are designed in terahertz frequency regime using a triangular microstrip patch resonator. Initially, a bandpass filter is designed at an operating frequency of 1.65 THz with a bandwidth of 65 GHz. Further a dual-band bandstop filter is designed with resonance frequencies of 1.25 THz and 2.14 THz. In both designs, the triangular patch is coupled to the transmission line to achieve bandpass and bandstop characteristics. A graphene layer is deposited between the dielectric and the conductor layer to enhance the propagation of plasmonic waves. The simulation results reveal that the designed filters are capable of achieving the desired frequency response. By varying the graphene’s chemical potential, a shift in the transmission response’s resonance frequency is observed. The proposed filters have the potential to be used as key components for future terahertz band communications systems.

Topological resonators based on hexagonal-star valley photonic crystals

In valley photonic crystals, topological edge states can be gained by breaking the spatial inversion symmetry without breaking time-reversal symmetry or creating pseudo-spin structures, making highly unidirectional light transmission easy to achieve. This paper presents a novel physical model of a hexagonal-star valley photonic crystal. Simulations based on the finite element method (FEM) are performed to investigate the propagation of TM polarized mode and its application to ring resonators. The results show that such a topologically triangular ring resonator exhibits an optimum quality factor Q of about 1.25 × 104, and Q has a maximum value for both frequency and the cavity length L. Our findings are expected to have significant implications for developing topological lasers and wavelength division multiplexers.

Filtering linear polarization converters based on multi-mode unit for harmonic suppression

In this article, a class of filtering linear polarization converters based on a single quasi-single-layer triangular resonator unit is proposed. By loading the stub-line and slot lines, the degenerate modes of the single fundamental resonant mode of an isosceles right-angle patch are separated into two for a second-order filtering characteristic, and two additional resonant modes are then generated for the second conversion band. Attributed to the mixed electric and magnetic coupling in the coupling section of the loaded stub-line, several conversion zeros are introduced at the same time. As the contribution of this work, multiple resonant modes and conversion zeros can be independently controlled by the corresponding parameters, enabling second-order single- and dual-band response with multi-mode high selectivity side-band and harmonic rejection characteristics out-of-band. With the detailed analysis of the surface current and field distributions, the polarization conversion mechanisms are revealed. Finally, the single-band and dual-band linear polarization converters are processed, and the measured and simulated results are in good agreement. As expected, the two polarization converters show excellent filtering features, which is beneficial for improving modulation accuracy and avoiding unwanted electromagnetic interference in various applications of multi-passband and multi-functional metasurfaces.

Theoretical analysis of graphene loaded equilateral triangular dielectric resonator antenna

Theoretical analysis of graphene loaded equilateral triangular dielectric resonator antenna

Wideband High-Selective Linear Polarization Converter and Its Application in Bifunctional Metasurface for Reduced Isolation Band

In this article, a wideband high-selectivity filtering linear polarization converter is proposed and applied for ultranarrow isolation-band bifunctional metasurface. As the contribution of this work, the developed polarization converter based on slot-line loaded triangular resonator unit not only achieves the in-band multimode resonant characteristic, but also introduces two additional controllable zeros out-of-band, so as to enable simultaneous implementation of the wideband and high selectivity features. With the detailed analysis of the modes, field, and surface current distributions, the mechanisms of wideband, high selectivity, and polarization conversion are revealed. Finally, the linear polarization converter as well as the bifunctional metasurface are fabricated for demonstration. The linear polarization converter can attain a conversion bandwidth of 45% under a polarization conversion ratio of >90%. Due to the excellent filtering characteristic of the proposed linear polarization converter, the constructed bifunctional metasurface can reduce its isolation band to only 2.7%. As expected, the proposed converter has the attractive advantages of wideband operation and high selectivity, which are of great significance for reducing the isolation-band and improving the spectral utilization in various applications of multifunctional metasurfaces.

Design of a Compact Quad-Channel Microstrip Diplexer for L and S Band Applications

In this paper, two novel dual-band bandpass filters (BPFs) and a compact quad-channel diplexer working at 1.7/3.3 GHz and 1.9/3.6 GHz are proposed. In the proposed diplexer design, triangular loop resonators and rectangular loop resonators are used together to reduce the circuit size and improve diplexer performances. Insertion loss (IL) and return loss (RL) of the proposed diplexer are better than 0.8 dB and 21 dB, respectively, at these four operating frequencies. Output ports isolation parameter is better than 30 dB. With the achieved specifications, the proposed diplexer can be used in L and S band applications.

A Metamaterial-Based Double-Sided Bowtie Antenna for Intelligent Transport System Communications Operating in Public Safety Band

In this paper, a compact design and new structure of bowtie antenna with dual-band characteristics for the 5G and public safety bands in intelligent transport systems (ITS) is presented. The antenna consists of a double-sided bowtie radiating patch with partial ground plane. A triangular complementary split-ring resonator (TCSRR) metamaterial (MTM) structure was etched on the radiating patch, to develop a dual band and a single notch band between 3.85 and 4.65 GHz. The proposed antenna had an overall size of 36 × 36 mm2 and was fabricated using a FR4 substrate with a thickness and dielectric permittivity (εr) of 1.6 mm and 4.3, respectively. CST microwave studio software was used for the design of antenna. The measured frequency results show impedance bandwidths of 3.45–3.85 GHz and 4.65–5.4 GHz, for a voltage standing wave ratio (VSWR) less than 2. The proposed antenna operates at 3.5 GHz and 4.9 GHz, providing bandwidths of 400 MHz and 750 MHz, respectively, which cover the 5G and public safety bands. A prototype was fabricated and measured based upon optimal parameters, and the experimental results showed consistency with the simulation results. The proposed antenna provided a simulated/measured gain of 5.64 dBi/5 dBi and 4 dBi/3.7 dBi at 3.5 GHz and 4.9 GHz, respectively. The enhanced bandwidth and better gain results of the proposed antenna make it an ideal candidate for an ITS operating in the 5G and public safety bands.

Wideband and function-switchable polarization converter based on multi-mode active metasurface

A linear polarization converter based on multi-mode active metasurface is proposed to achieve wideband/dual-band, function-switch, low profile, filter and reflection, including two slot-loaded right-angle triangular resonators connected by two PIN diodes. The switchable function of the linear polarization converter between wideband and dual-band is realized by controlling the OFF/ON states of the diodes. By detailed analysis of the field/current distribution and polarization components in different modes of the multi-mode resonator unit, the filtering characteristic and magnetic-resonant-based polarization conversion mechanism between wideband and dual-band are revealed. A function-switchable filtering reflective linear polarization converter is designed, fabricated, and measured, presenting single bandwidth of 6.43–10.16 GHz, dual bandwidths of 6.08–6.39 GHz, and 11.7–12.54 GHz in the OFF- and ON-state, respectively. In both states, the polarization conversion ratios both exceed 90 %. Results show that the proposed reflective linear polarization converter has excellent switchable function, low profile and filtering linear polarization conversion.

Development of a continuous operation hop-kiln with power supply

Introduction.Hop production in the Russian Federation averages 116 thousand tons from 54 thousand hectares. The HS-400 hop-kiln used in the hop drying process line is energy-intensive. The concept of hop growing development in the Chuvash Republic for 2020–2025, approved by the decree of the Cabinet of Ministers of the Chuvash Republic (dated 20.08.2020 No. 738-r), provides for the development of up to 45–50 hectares of new areas for hop, at the rate of 15–17 hectares per one hop-kiln HS-400. To expand the production of hop, it is necessary to effectively master innovative technologies and installations for drying freshly harvested hop that are not inferior in technical and economic parameters of foreign analogues. The development of a hop-kiln that provides dehydration and disinfection of freshly harvested hop, pre-servs consumer properties with reduced operating costs, is currently relevant.Methodology.The electrophysical parameters of hop cones (according to the Rogov method) were analyzed depending on the frequency of the electromagnetic field, humidity and temperature, heat and mass transfer processes during the supply of convective heat to the volumetric resonator of the microwave installation were theoretically investigated, and the effective technological parameters of the hop-kiln were determined. Studies of the electromagnetic field strength, current density, and intrinsic Q-factor of resonators were carried out in the CST Studio Suite 2017 three-dimensional computer modeling program and its CST Microwave Studio subprogram.Results.A multi-resonator hop-kiln with an energy supply in an electromagnetic field has been developed. The proposed hop-kiln contains resonators sequentially arranged in a horizontal plane with curved surfaces, docked through ceramic biconvex perforated plates. The design and technological scheme of the hop-kiln has been developed. The intrinsic Q-factor of elliptical toroidal resonator is 14600, of triangular prismatic resonator — in the range of 9000–1200, depending on the degree of concavity of the upper face. The calculation of the installation productivity amounts to 180–200 kg/h with a power of 15.66 kW, which made it possible to determine energy costs — to 0.1 kWh/kg.

Hexagonal-Triangular Combinatorial Structure Based Dual-Band Circularly Polarized Patch Antenna for GAGAN Receivers

A multilayer gap-coupled dual band hexagonal microstrip patch antenna is presented for GPS Aided GEO Augmented Navigation (GAGAN) receivers. GAGAN is developed by AAI (Airport Authority of India) and ISRO (Indian Space Research Organization) exclusively for aviation purposes with the GPS frequencies L5 (1176.45 MHz) and L1 (1575.42 MHz). The proposed GAGAN antenna has three trapezoidal and four equilateral triangular patch resonators configured to form a gap-coupled hexagonal patch on the top layer and seven equilateral triangular patches with slots in between to form the middle layer. Both the layers are fed by a single coax feed to achieve a dual band compact microstrip antenna of size 55 mm x 55 mm x 3.2 mm. Instead of designing the hexagonal antenna conventionally from a circular patch antenna, the sides of the equilateral triangular patch are truncated to obtain the proposed compact hexagonal antenna as the triangular antenna occupies less area when compared to circular or square patches for a fixed frequency. To bring in novelty with improved performance, the combinatorial structured configuration has been explored through step-by-step optimization. The aspects of GAGAN requirements like circular polarization with a single input, dual band operation and high gain with gain flatness are achieved with this compact structured antenna when compared to square and circular patch antennas. The combinatorial structures such as perturbation and truncation introduced in the patches are responsible for exciting two near-degenerate orthogonal modes producing circular polarization (CP). A cross slot etched in the center patch results in gain enhancement with a gain above 3.2 dBi over a bandwidth of 20 MHz in both the bands. Five shorting pins are added to achieve high impedance matching and good CP with an axial ratio (AR) below 2 dB. The simulated and measured results are found to be in good agreement with greater than 20 MHz operational bandwidth exhibiting CP with an omni-directional radiation pattern having high cross polar levels of -22 dB. The size reduction achieved in the proposed design is 56.79% when compared to the conventional hexagonal patch antenna. The measured 10 dB impedance bandwidth is 2.7% and 2.1% for L5 and L1 bands respectively with a 3 dB AR bandwidth of 2.3% for L5 and 2.0% for L1, satisfying GAGAN requirements.