Triple Band Research Articles

Numerical analysis of the Brewster-electrical duo-effect for multi-resonance tuning in THz absorber

The excitation and tuning of multiple resonances with narrow spectral width based on Brewster's effect is possible in an ultrathin dual-band terahertz absorber. The angular variation establishes a monotonic relation with the frequency of some generated resonances offering tunability. Moreover, burying a graphene ring resonator beneath the metallic ring splits the resonance for providing the triple narrow absorption windows. The electrical modulation offers the feature of independent tunability in the generated third absorption band. Thus, the frequency ratio of the upper to lower spectral absorption peak can be modulated by the electrically tunable Fermi energy of graphene. Engraving the graphene resonator also enhances the incident angle based tunability by affecting a greater number of Brewster generated resonance peaks. The narrow line shape of the triple band absorption can enable refractive index sensing and the detection of extraneous elements in localized analyte samples. The detection of imidacloprid pesticide in wheat flour is performed by the implemented sensor. The numerical analysis is done for the design and analysis of the absorber structures to report the above facts.

A compact high gain filtering patch antenna for multiband wireless system

A novel compact multilayer patch antenna is designed for triple-band operation with filtering characteristics. The multiband antenna with filtering characteristics is necessary to suppress adjacent band interference. Further, it brings higher out-of-band suppression without deteriorating the in-band gain. This filtering antenna offers size compactness, high gain, and high selectivity with reduced interference. On exciting the antenna, the electromagnetic (EM) coupling takes place from feed to patch through the slotted ground. Then the magnetic field reaches its maximum at the middle of the rectangle patch while the electric field reaches its maximum at the edges. These fields couple with the ‘U’ shaped metallic loops and bring field distribution in it and thus contribute to dual-band resonance at 2.45GHz and 4.15GHz. For better impedance matching, the two ‘U’ shaped metallic loops are employed. The additional middle band at 3.25GHz is attained through the employment of a split rectangular ring around the center patch. The bottom ground is etched with a bent horizontal slot to achieve proper positioning of the lower resonance. The modified CRLH feeding structure is adopted in this antenna to realize radiation null between operating bands. The dimension of the CRLH branches decides the positioning of radiation nulls in the spectrum of interest. This null reduces the interband interference and it is an important feature for any multiband communication system. The usage of via between patch and feed increases the electrical length of an antenna and thus provides size miniaturization. Whereas the position of the via in the patch decides the impedance matching. thus multiple iterations of simulation were done to optimize the via position for better impedance matching. The designed antenna has a compact dimension of 0.21λo × 0.21λo. The realized triple bands have −10dB impedance bandwidth of 180MHz (2.31 to 2.49GHz), 350MHz (3.1 to 3.45GHz), and 850MHz (3.6 to 4.45GHz) with a maximum gain of 5.2dB. Thus the multi-layer antenna not only has proven to be multiband but also incorporated filtering characteristics to lessen interband interferences. The proposed antenna would be beneficial in a multiband wireless system that supports services such as Wifi, WiMAX, and 5G. The antenna is the perfect candidate for the unmanned ariel vehicle (UAV) to be used in emergency and military applications.

Rotational symmetric solar system shaped triple band perfect metamaterial absorber for S-, C-, and X-band application

This article offers a metamaterial absorber of solar system shaped design for S-, C-, and X-band using a simple and symmetric structure. This innovative structure consists of two split ring resonator (SRRs) and two circular shape metal strips with a metal disc in the center. The ground metallic layer and upper patches are disjoint by flame retardant dielectric FR-4 (lossy) material of thickness 1.6 mm. Copper (annealed) of depth 0.035 mm is used for the all patches as well as the ground layer. The electrical dimension of the unit cell is 0.1006 λ × 0.1006λ which is calculated at the lower frequency 3.02 GHz. Computer simulation technique (CST) microwave studio is used to derive the numerical results. The simulation result yields three resonance peaks at 3.02, 5.71 and 8.36 GHz with the absorption 99.86%, 97.58% and 97.46%, respectively. The electric field, magnetic field and the surface current distribution are studied to comprehend the absorption mechanism. The reflection coefficient (S11) is also investigated by advanced design system (ADS) electrical equivalent circuit. This unique design of metamaterial absorber (MMA) unit cell is finalized through some parametric studies. The simulated results are also validated by ADS with electrical equivalent circuit and different array orientation. Unit cell, 1 × 2, 2 × 2 and 4 × 4 array of the unit cell are fabricated for measurement purposes. The measurement is carried out with the help of programmable network access (PNA) of Agilent N5227 with waveguide ports. The S-, C-, and X-band are mainly used for satellite communication and radar system. S-band is used for the shipping, aviation and space industries for its efficiency as a conduit for supplying vital real-time data whereas, C band is used for many wireless communication like satellite transmissions, Wi-Fi devices, mobile communication and weather forecasting system. X band is a radar sub-band which is utilized in civil, military, weather monitoring, air traffic control, maritime vessel traffic control, defense tracking.

A triple band square-interlinked-rhombus shaped metamaterial absorber for microwave C and X-band utilizations

A triple band square-interlinked-rhombus shaped metamaterial absorber for microwave C and X-band utilizations

A Metamaterial Inspired Multiband Conformal Bandpass Filter with Improved Quality Factor for Sub-6 GHz Wireless Communication Applications

This paper deals with the design, simulation, and practical modeling of metamaterial-based multiband conformal bandpass filter (BPF) for various wireless communication applications with improved quality factors. The novel metamaterial in the form of a split ring resonator is loaded on the ground plane face of the proposed BPF. The overall dimension of the designed BPF is only [Formula: see text]. The proposed BPF is tuned initially for quality factor enhancement based on the thickness of the substrate, physical parameters of the f transmission line, ground plane, externally loaded elements, and the gap in the metamaterial loading. The suggested filter operates at triple band covering the frequency bands from 1.4 to 2.2, 3.6 to 3.9, and 4.8 to 5.9[Formula: see text]GHz, which are suitable for sub-6[Formula: see text]GHz 5G and other wireless applications. The insertion loss is observed as 1[Formula: see text]dB, which is suitable for the proposed BPF. The conformal behavior of the filter is judged through bending deformation analysis at various bending positions like (15[Formula: see text], 30[Formula: see text], 45[Formula: see text], 60[Formula: see text], and 90[Formula: see text]). The proposed BPF retains triple pass band characteristics at various bending deformations, which makes it suitable to be used in curved structures or flexible circuitry. The theory of equivalent circuits and quality factor [Formula: see text] of the designed BPF is discussed in this paper. The results are analyzed experimentally through ANRITSU-MS2037C combinational analyzer. The proposed BPF is suitable for sub-6 GHz 5G, WLAN, and Wi-Max applications.

Triple band frequency tunable polarization insensitive metamaterial absorber for WLAN and 5G applications

A triple band metamaterial absorber (MMA) has been demonstrated in this paper that is developed on an FR4 substrate targeting WLAN and 5G frequencies. The resonating patch contains three modified concentric copper rings having overall unit cell dimensions of 0.16λ0 × 0.16λ0 × 0.0128λ0, where the wavelength, λ0 is for 2.4 GHz. The MMA exhibits 99.3%, 95.68%, and 99.5% peak absorption at 2.4, 3.5, and 5.85 GHz, respectively. Length variation of inwardly extended metallic stubs attached to the innermost ring provides frequency tuning flexibility for peak absorption within 5.67 GHz–5.98 GHz. The absorption process of the MMA is analyzed through the distribution of surface current. The MMA exhibits incident and polarization angle insensitive behaviour up to 60° for both TE and TM modes with near zero polarization conversion ratio. The resonance characteristics are justified through equivalent circuit modelling with validation by Advanced Design software (ADS). The measured absorption indicates a close resemblance with the simulation. Moreover, a good effective medium ratio of 6.25 shows the compactness of MMA. Due to its compact structure, incident, and polarization angle insensitivity, and near unity absorption at application-specific frequencies, this perfect MMA can be suitable for WLAN and 5G applications, especially for microwave shielding and sensing.

Gain-enhanced triple-band rectifier-integrated antenna for microwave wireless power transmission

Abstract This paper proposes a triple-band fractal slot antenna with enhanced gain operating at frequencies of 2.7, 3.5, and 4.8 GHz for microwave wireless power transmission. The antenna achieved more than 3 dB gain by preserving the symmetrical defected reflector structure behind it at a length of 0.54λ/4, where λ is the wavelength in free space at 2.7 GHz. A 50 Ω micro-strip line coupled at 66 mm length helps feed the triple band slot antenna. The purpose of a triple-band rectifier circuit with an impedance network is to convert the radio frequency (RF) signal into direct current. The measurements reveal that the antenna’s enhanced gain is 8.8 dB, and the rectifier’s highest RF signal to direct current conversion efficiency is 74.3%. For the combined configuration unit of measure, the antenna is assimilated into the rectifier via back-to-back 50 Ω Sub Miniature Version A (SMA) connectors. The highest recorded efficiency of 49.67% was obtained for the rectenna at optimum values of 1 kΩ resistive load and −5 dBm power input. It has been revealed that the rectifier-integrated antenna presented is effective for low-input RF energy capture and power transmission.

A triple band high gain THz antenna for satellite, space and terrestrial applications

A triple band high gain THz antenna for satellite, space and terrestrial applications

A Simulated Model of a Triple Band Patch Antenna Proposed for Vital Signs Monitoring Equipment

In the modern lifestyle, an increase in psychological pressures was observed, leading to an increase in various diseases, which increased the need for diagnosis and treatment, (i.e., increased demand for) equipment to monitor vital activities, Therefore, a microstrip patch antenna was suggested as the topic of this article because it is popular in wireless systems due to its low cost, lightweight, and thin profile. The proposed design is made of FR-4 as a substrate material, and copper for the patch and the ground. The reader can notice that our proposed antenna owns the following resonance frequencies: (3.68), (6.48), and (7.93) GHz respectively. The gain values for the previous resonance frequencies were respectively (27) dBi, (11.1) dBi, and (4.19) dBi, while the values of directivity were (32.17) dBi, (15.70) dBi, and (7.984) dBi. The radiation efficiency values were (-5.179) dB, (-4.561) dB, and (-3.789) dB, while the values of the total efficiency were (-5.207) dB, (-4.631) dB, and (-3.799) dB The operating bandwidths were: (0.1146) GHz, (0.2764) GHz, and (0.3641) GHz. The design was simulated with CST software.

Flower-shape resonator-based triple-band metamaterial wave absorbers to find the dispersion relation utilizing one dimensional (1-D) periodic waveguide

This paper proposes a flower-shape resonator-based triple band with a high-performance metamaterial wave absorber to find the dispersion relation utilizing one dimensional (1-D) periodic waveguide. The proposed absorber comprises flower-shaped square split ring resonator-based resonators separated by a Rogers RT5870 (lossy) dielectric layer with a thickness of 1.575 mm and back annealed copper with 0.035 mm thickness, and the size of the unit cell is 8 mm × 8 mm. The outcomes of simulations conducted using the Computer Simulator Technology (CST) Microwave Studio simulator reveal the presence of three absorption peaks at frequencies of 5.032, 7.96, and 13.94 GHz with an absorption of 99.709%, 99.966%, and 99.973%, respectively. As a result, this work presents a substitute concept in terms of phase velocity of mode in limited with periodic arrangements, showing it determines the type with terms of modalities a one-dimensional periodic concave parallel plates wavelength. The suggested phase velocity has been analysed using simulations using the CST Microwave Studio simulator and the CST eigenmode solver. A comparable circuit analysis demonstrates the superior performance of the metamaterial wave absorber, indicating its potential for excellent functionality within the advanced design system (ADS) software. Additionally, the proposed structures, modelled with the High-Frequency Structure Simulator (HFSS), exhibit a close correspondence with the maximum absorbance observed at each resonance peak in CST simulation results. The proposed research demonstrates excellent features such as unity absorption, angle insensitivity, and more, making it highly suitable for dispersion relation as well as C, X, and Ku band applications.

A Triband Compact Antenna for Wireless Applications

This paper presents the implementation of a triple band microstrip patch antenna based on modified split ring resonator (SRR) and modified complementary split ring resonator (CSRR) as defected ground plane. The antenna is designed in a FR4 substrate of dielectric constant 4.4 with dimensions as 35 mm × 35 mm × 1.6 mm that comprises a total designed antenna volume of 1960 mm3. Multiband operation is introduced in the antenna through multiple resonators that are introduced in the patch. Impedance matching was provided with the help of partial ground plane and modified SRR in patch. The simulation performance of the antenna is verified using high frequency structural simulator (HFSS) software. The designed antenna resonates at 2.8 GHz, 5.8 GHz, and 6.9 GHz for the application requirements of WiMAX, ISM, and Sub-7 GHz wireless communication. The antenna is fabricated as printed circuit board (PCB) format, and its return loss characteristics are measured using a vector network analyser (VNA). The measurement results of the proposed triband antenna are in good agreement with simulated return loss characteristics.

A triple band local oscillator coupling system based on a phase grating for five-meter Dome-A terahertz explorer telescope.

For heterodyne receivers, broadband and integrated local oscillator (LO) coupling schemes are crucial. In this paper, we present a novel terahertz broadband receiver system based on a one-pixel phase grating. We designed a phase grating that can simultaneously couple the LO signals at 690, 850, and 1300GHz to a superconducting hot-electron bolometer mixer at the incident angles of 25.7°, 20.6°, and 13.3°, respectively. At these three frequencies, the measured diffraction efficiencies of the phase grating are as high as 70%, 73%, and 65%, and the total power coupling efficiencies of the LO coupling system are 22%, 23%, and 23%, in good agreement with the simulated results. This efficient and highly integrated multiband receiver system has potential applications in the proposed Five-meter Dome-A Terahertz Explorer telescope.

Polarization–Insensitive Angularly Stable Compact Triple Band Stop Frequency Selective Surface for Shielding Electromagnetic Radiations

Polarization–Insensitive Angularly Stable Compact Triple Band Stop Frequency Selective Surface for Shielding Electromagnetic Radiations

Dust Enrichment and Grain Growth in a Smooth Disk around the DG Tau Protostar Revealed by ALMA Triple Bands Frequency Observations

Characterizing the physical properties of dust grains in a protoplanetary disk is critical to comprehending the planet formation process. Our study presents Atacama Large Millimeter/submillimeter Array (ALMA) high-resolution observations of the young protoplanetary disk around DG Tau at a 1.3 mm dust continuum. The observations, with a spatial resolution of ≈0.″04, or ≈5 au, revealed a geometrically thin and smooth disk without substantial substructures, suggesting that the disk retains the initial conditions of the planet formation. To further analyze the distributions of dust surface density, temperature, and grain size, we conducted a multiband analysis with several dust models, incorporating ALMA archival data of the 0.87 and 3.1 mm dust polarization. The results showed that the Toomre Q parameter is ≲2 at a 20 au radius, assuming a dust-to-gas mass ratio of 0.01. This implies that a higher dust-to-gas mass ratio is necessary to stabilize the disk. The grain sizes depend on the dust models, and for the DSHARP compact dust, they were found to be smaller than ∼400 μm in the inner region (r ≲ 20 au) while exceeding larger than 3 mm in the outer part. Radiative transfer calculations show that the dust scale height is lower than at least one-third of the gas scale height. These distributions of dust enrichment, grain sizes, and weak turbulence strength may have significant implications for the formation of planetesimals through mechanisms such as streaming instability. We also discuss the CO snowline effect and collisional fragmentation in dust coagulation for the origin of the dust size distribution.

Triple‐band circularly polarized conformal antenna for vehicular communication applications

AbstractVehicular communication presents a compact wideband implantable antenna for the best wireless transmission of information. The key role of the antenna is handled by the thickness of the substrate present in that antenna. Also, the shape of the antenna causes the performance characteristics. Now, vehicle‐to‐vehicle communication is the interesting task for designers to create successful and organized vehicular communication systems. This article presents a triple‐band circularly polarized conformal antenna for vehicular communication. An antenna is introduced as a triple‐band circular polarized conformal antenna and preserved a suitable mount on the vehicle surface for greater gain to provide well‐maintained operational performance characteristics. For getting circular polarization, circular cuttings are provided in the design of the proposed antenna. The radiation gives a fixed direction by providing 0.3 mm thickness. Here, use a circularly polarized antenna to rectify the signal absorption due to the contact material used in the antenna. A polyamide material is used as a substrate to get a probable successful link and improve the flexibility of the antenna. The triple‐band circularly polarized antenna is designed to operate in vehicular communication bands such as 2.4 GHz Wi‐Fi, 3.5 GHz WiMAX, and 5.9 GHz dedicated short range communication. The antenna is designed to resonate in a triple band to improve the antenna parameters like frequency response characteristics, gain, return loss, voltage standing wave ratio, left hand circularly polarization, right hand circularly polarization, axial ratio, fidelity factor, directivity, radiated power, and input impedance. Under the operating frequency bands of 2.4, 3.4, and 5.9 GHz, the efficiency of the proposed antenna is 98.48%, 97.31%, and 97.90%, respectively. The triple‐band circularly polarized conformal antenna is implemented in the high‐frequency structure simulator platform. The proposed tri‐band antenna is applicable in vehicular communication systems and healthcare for efficient wireless transmission.

Incident angle dependent tunable multiband infrared absorption based sensor

The effect of electromagnetic (EM) resonance in the graphene resonator and multiple reflections taking place in the dielectric spacer can provide the multiband infrared absorption. The intensity of resonance spectrum occurring due to the formation of EM dipoles in resonator can be controlled by patterning it using desired perturbation. The absorber response can be set with the multiple narrow and broad absorption peaks together by modulating the electrical properties of graphene material. The proposed absorber provides the incident angle dependent behavior with linear variation in the resonant wavelengths by maintaining the high absorption. This can provide a new way of tuning the antenna response by angle of incidence. The implemented absorber can provide the triple narrow bands which can be utilized for performing the refractive index sensing. The proposed absorber provides a significant value of sensing performance parameters including sensitivity, full-width-half-maxima, and figure-of-merit with the high value of quality factor. Moreover, the proposed absorber offers the ability of generating an extra narrow absorption band in the case of presence of sensing analyte of specific thickness and refractive index range making it highly sensitive for the detection of specific surroundings including the bio-cells, chemicals and humidity in the air. The broadband characteristics of the proposer absorber can be utilized in implementing the infrared EM shields and thermal storage components.

Additively Manufactured Metal-Only Waveguide-Based Millimeter-Wave Broadband Achromatic Reflectarrays

This communication demonstrates additively manufactured metal-only waveguide-based tri-band and broadband reflectarray antennas. The unit cell (UC) is implemented by cascading two metal waveguide sections with different cut-off frequencies (fc1 and fc2 (fc1< fc2)). When illuminated with the feed antenna, the reflectarray provides different reflection paths to compensate for the spatial phase delay over triple bands, fl (fl<fc1), fm (fc1 <fm<fc2), and fh (fh>fc2). By tuning the length of the two waveguide sections and vertically adjusting the position of the UC, the phase-shifting over the triple bands can be independently controlled. In addition, because of the sharp selectivity of the waveguide, a reflectarray with the broadband achromatic feature can be achieved by properly selecting the tri-band’s frequency and the cut-off frequency of the waveguides. A tri-band reflectarray centering at 25 GHz (low-band), 32 GHz (middle-band), and 37 GHz (high-band) is designed firstly to demonstrate the independent beam shaping over triple bands. Then, two waveguide-based reflectarrays with the broadband achromatic feature are designed, which show stable performance from 22 GHz to 38 GHz with a relative bandwidth of 53.3%. The prototypes are conveniently fabricated using additive manufacturing, and their performance is experimentally verified.

An ML-Based Approach for HCF Life Prediction of Additively Manufactured AlSi10Mg Considering the Effects of Powder Size and Fatigue Damage

As a popular technique, additive manufacturing (AM) has garnered extensive utilization in various engineering domains. Given that numerous AM metal components are exposed to fatigue loads, it is of significant importance to investigate the life prediction methodology. This study aims to investigate the high-cycle fatigue (HCF) behavior of AM AlSi10Mg, taking into account the influences of powder size and fatigue damage, and a novel ML-based approach for life prediction is presented. First, the damage-coupled constitutive model and fatigue damage model are derived, and the Particle Swarm Optimization method is employed for the material parameters’ calibration of M AlSi10Mg. Second, the numerical implementation of theoretical models is carried out via the development of a user-defined material subroutine. The predicted fatigue lives of AM AlSi10Mg with varying powder sizes fall within the triple error band, which verifies the numerical method and the calibrated material parameters. After that, the machine learning approach for HCF life prediction is presented, and the Random Forest (RF) and K-Nearest Neighbor (KNN) models are employed to predict the fatigue lives of AM AlSi10Mg. The RF model achieves a smaller MSE and a larger R2 value compared to the KNN model, signifying its superior performance in predicting the overall behavior of AM AlSi10Mg. Under the same maximum stress, a decrease in the stress ratio from 0.5 to −1 leads to a reduction in fatigue life for both powder sizes. As the powder size decreases, the rate of damage evolution accelerates, leading to shorter fatigue life.

A Triple Band Substrate Integrated Waveguide with Dielectric Resonator Antenna for 4G and 5G Applications.

A triple-band substrate integrated waveguide (SIW) with dielectric resonator antenna (DRA) for fourth-generation (4G) and fifth-generation (5G) applications is proposed and analyzed in this paper. Loading SIW with DRA allows for a wide bandwidth, low losses, and fabrication ease. The proposed antenna can transmit and receive data independently by covering LTE Band 3 at 1.8 GHz, LTE Band 8 at 2.6 GHz, and 5G n77 at 3.7 GHz. A U-shaped cut is applied to achieve the targeted multi-resonance frequencies. The antenna obtains high bandwidths of up to 19.50% with 4.9 dBi gain and 81.0% efficiency at 1.8 GHz, 6.58% bandwidth with 4.4 dBi and 72.7% efficiency at 2.6 GHz, and 8.21% bandwidth with 6.7 dBi and 73.5% efficiency at 3.7 GHz. The simulated and measured results agree well. The proposed antenna is feasible for 4G and 5G applications.

Sequential Multistep Excited‐State Structural Transformations in N,N′‐Diphenyl‐dihydrodibenzo[a,c]phenazine Fluorophores

AbstractWe demonstrate that a single polycyclic π‐scaffold can undergo sequential multistep excited‐state structural evolution along the bent, planar, and twisted conformers, which coexist to produce intrinsic multiple fluorescence emissions in room‐temperature solution. By installing a methyl or trifluoromethyl group on the ortho‐site of N,N′‐diphenyl‐dihydrodibenzo[a,c]phenazine (DPAC), the enhanced steric effects change the fluorescence emission of DPAC from a dominant red band to well‐resolved triple bands. The ultra‐broadband triple emissions of ortho‐substituted DPACs range from ≈350 to ≈850 nm, which is unprecedented for small fluorophores with molecular weight of &lt;500. Ultrafast spectroscopy and theoretical calculations clearly reveal that the above dramatic changes originate from the influence of steric hindrance on the shape of excited state potential energy surface (S1 PES). Compared to the steep S1 PES of parental DPAC, the introduction of ortho‐substituent is shown to make the path of structural evolution in S1 wider and flatter, so the ortho‐substituted derivatives exhibit slower structural transformations from bent to planar and then to twisted forms, yielding intrinsic triple emission. The results provide the proof of concept that the bent, planar, and twisted emissive states can coexist in the same S1 PES, which greatly expand the fundamental understanding of the excited‐state structural relaxation.