Communication Band Research Articles

Design and investigation of UWB antenna with triple notched band for 5G wireless communication

ABSTRACT Two novel antennas are presented in this article. UWB and UWB antenna with triple notched band are designed using an elliptical array structure. To improve the gain and the impedance bandwidth, a new methodology for optimization of an elliptical array UWB antenna with an uncentered feedline model is presented. Based on the Response Surface Modelling, two parameters (Wopt1 and Wopt2) control the return loss of UWB antenna. The mathematical models of S11 is developed using non-regression analysis, and this antenna can be used for various applications such as Wi-Fi, 5 G, 4 G LTE, X-Band application, C-Band application. The band rejection technique is implemented to designed triple notched UWB antenna to reduce the cost of the UWB channel. The first band (2–3 GHz) is rejected by embedding a rectangular stub on the modified partial ground plane on UWB antenna. By etching a three rectangular slot on the elliptical array radiator, two notched bands 2–3 GHz and 5–6 GHz bands are rejected. By embedding two arcs on the elliptical array radiator, triple interfacing bands 2–3 GHz, 5–6 GHz, and 7.8–8.4 GHz are rejected. Two proposed antennas are designed using FR4 substrate and fabricated and verified experimentally. This antenna offers excellent performance and is well-suited for 5 G wireless communications.

Ultra‐Broadband Emission in Bi/Ge Co‐Doped Silica Glass and Fiber via Bismuth Coordination Engineering

AbstractBismuth (Bi) and Germanium (Ge) co‐doped silica glass and fiber, as advanced gain media with broadband near‐infrared (NIR) emission and amplification, have promise for extending communication bandwidth. However, efficiently modulating the NIR emissions of bismuth to cover the C+L communication bands remain a significant challenge. In the study, a high‐temperature and high‐pressure reduction treatment on Bi/Ge co‐doped silica glass is employed to tailor the coordination environment around bismuth active center. This method facilitated the creation of new bismuth NIR luminescence centers, resulting in the luminescence spectrum with a peak position at 1550 nm and a FWHM exceeding 350 nm. The changes in the bismuth coordination environment are elucidated using HRTEM, photoluminescence decay, temperature‐dependent emission, EXAFS and CW‐EPR. Furthermore, the feasibility of this method in Bi/Ge co‐doped silica fiber is validated, and obtained >5 dB amplification in the range of 1400–1700 nm. This coordination engineering method holds significant potential for widespread application in Bi/Ge co‐doped silica glass and optical fiber is believed. It presents a promising prospect for expanding communication bandwidth by effectively modulating the NIR emissions of bismuth to cover the S to U communication band.

Excellent Low-Frequency Microwave Absorption and High Thermal Conductivity in Polydimethylsiloxane Composites Endowed by Hydrangea-Like CoNi@BN Heterostructure Fillers.

The advancement of thin, lightweight, and high-power electronic devices has increasingly exacerbated issues related to electromagnetic interference and heat accumulation. To address these challenges, a spray-drying-sintering process is employed to assemble chain-like CoNi and flake boron nitride (BN) into hydrangea-like CoNi@BN heterostructure fillers. These fillers are then composited with polydimethylsiloxane (PDMS) to develop CoNi@BN/PDMS composites, which integrate low-frequency microwave absorption and thermal conductivity. When the volume fraction of CoNi@BN is 44 vol% and the mass ratio of CoNi to BN is 3:1, the CoNi@BN/PDMS composites exhibit optimal performance in both low-frequency microwave absorption and thermal conductivity. These composites achieve a minimum reflection loss of -49.9dB and a low-frequency effective absorption bandwidth of 2.40GHz (3.92-6.32GHz) at a thickness of 4.4mm, fully covering the n79 band (4.4-5.0GHz) for 5G communications. Meanwhile, the in-plane thermal conductivity (λ∥) of the CoNi@BN/PDMS composites is 7.31W m-1 K-1, which is ≈11.4 times of the λ∥ (0.64W m-1 K-1) for pure PDMS, and 32% higher than that of the (CoNi/BN)/PDMS composites (5.52W m-1 K-1) with the same volume fraction of CoNi and BN obtained through direct mixing.

Er3+/Tm3+ codoped CaF2 based oxyfluoroborosilicate glass-ceramics for fiber laser applications

Transparent Er3+/Tm3+ codoped CaF2 based oxyfluoroborosilicate glass-ceramics (BSEr1TmxGCs) with variable Tm3+ concentration were prepared through melt quench process followed by reheat treatment at 450 °C/1h. They were characterized through differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) Raman spectroscopy, near infrared (NIR) emission and luminescence decay. The formation of CaF2 nanocrystallites against oxyfluoroborosilicate glassy phase was confirmed by scanning electron microscopic (SEM) and hi-resolution transmission electron microscopic (HRTEM) studies. The NIR emission properties were investigated at 460 nm diode laser pumping. The applicability of BSEr1TmxGCs were examined by evaluating effective bandwidth (Δλeff), stimulated emission cross-section (σe), gain bandwidth (σe × Δλeff), figure of merit (σe × τR) and quantum efficiency (ηQE). The energy transfer efficiency (ηET), rate of energy transfer (WET) between Er3+ and Tm3+ and the rate of non-radiative transitions (WNR) were also calculated. The comparative NIR emission performance suggests that the BSEr1Tm1GC has proficiency for 1530 nm broadband fiber lasers and optical amplifiers in short wavelength and conventional wavelength (S + C) band communication window.

Microwave absorber surface design for 5G energy harvesting applications

This study presents a high-efficiency microwave absorber for energy harvesting in 5G frequencies. Initially, a unit cell was designed in four stages to efficiently absorb in the targeted frequency region. The results obtained for each stage of the design were analyzed, and additional investigations were conducted for substrate material and thickness based on the optimum performance of the unit cell structure. A unit cell absorber designed on an FR4 a flame-resistant fiberglass/epoxy-based composite, commonly utilized in printed circuit boards due to its favorable electrical insulation properties and low cost. With a thickness of 1.5 mm, the absorber achieved a 98.04% absorption at 3.8 GHz according to simulation results. Subsequently, this unit cell was separately designed and simulated with different periodic arrays to transform into an absorber surface. As a result, high absorption rates of 98.94% and 98.35% were achieved at 3.8 GHz and 4.2 GHz, respectively, in the 2 × 2 array. It was observed that the structure absorbs over 85% within a 1 GHz bandwidth between 3.5 GHz and 4.5 GHz. Finally, a prototype of the absorber surface was manufactured, and measurements were taken in the laboratory environment. Significant agreement was found between the data obtained from these measurements and the simulation results. The results indicate that the suggested absorber surface is well-suited for energy harvesting within the n77 (3.3 GHz to 4.2 GHz) and n78 (3.3 GHz to 3.8 GHz) bands of 5G communication.

Low-loss and low-temperature Al2O3 thin films for integrated photonics and optical coatings

Amorphous aluminum oxide (Al2O3) is a key material in optical coatings due to its notable properties, including a broad transparency window (ultraviolet to mid-infrared) and excellent durability. Moreover, its higher refractive index contrast relative to silica cladding layers and high solubility of rare-earth ions make it well suited for optical waveguides and the development of various functionalities in integrated photonics. In many coatings and integrated photonics applications, the substrates are temperature and stress sensitive, while relatively thick (∼1 μm) alumina layers are required; thus, it is crucial to fabricate low optical loss alumina thin films at low deposition temperatures, while maintaining high deposition rates. In this study, plasma-assisted reactive magnetron sputtering, operated in an alternating current mode, is investigated as a reliable, straightforward, and wafer-scale compatible technique for the deposition of high optical quality and uniform Al2O3 thin films at low temperature. One-micrometer-thick amorphous Al2O3 planar waveguides, deposited at 150 °C and a rate of 23.3 nm/min, exhibit optical losses below 1 dB/cm at 638 nm and as low as 0.1 dB/cm in the conventional optical communication band.

Er3+ -doped oxyfluoroborosilicate glass ceramics with embedded CaF2 nanoparticles for 1.53 μm broad band applications

The CaF2 based oxyfluoroborosilicate glasses and glass ceramics doped with Er3+ ions were prepared via melt quench process followed by heat treatment and characterized for 1.53 μm broadband applications. The optimized glass ceramic sample was obtained at 450oC/1h heat treatment. The Er3+ concentration was optimized as 1.0 mol% for efficient emission at 460 nm excitation through concentration dependent luminescence analysis. The spectroscopic parameters such as Ωλ=2,4,6 parameters and the radiative parameters such as spontaneous transition probability rates (AR), branching ratios (βR) and decay times (τR) were calculated applying the standard Judd-Ofelt theory. The effective bandwidth (Δλeff), stimulated emission cross-section (σe), gain bandwidth (σe×Δλeff), quantum efficiency (η) and figure of merit (σe×τR) were calculated as 25.78 nm, 13.42×10-21 cm2, 3.46×10-26 cm3, 82.83% and 5.32×10-23 cm2s, respectively for the optimized glass ceramic sample. The exchange type of energy transfer among the excited Er3+ ions results the quenching in luminescence and the non-exponentiality in decay curves. The systematic investigations carried out indicate that the glass ceramic obtained at 450oC/1h heat treatment was proficient for 1.53 μm broadband fiber lasers and optical amplifiers in S and C band communication window.

ROAD value-based detection for GAE enhanced interference mitigation in LDACS.

The increasing volume of air traffic has placed significant stress on the current Air Traffic Management (ATM) systems, especially concerning the use of Very High Frequency (VHF) communication bands. As air traffic continues to grow, the limitations of the existing spectrum and infrastructure necessitate significant upgrades to ensure safety, efficiency, and capacity. The modernization of air traffic management systems has led to the development and introduction of the L-band Digital Aeronautical Communication System (LDACS), a new communication protocol. LDACS is designed to operate alongside existing L-band systems, ensuring compatibility with legacy users. The coexistence of LDACS with legacy systems poses significant interference challenges, as any disruption in data retrieval can critically impact flight safety. This paper proposes four potential interference mitigation techniques that LDACS can employ to detect and reduce the primary source of interference: Distance Measuring Equipment (DME). The authors introduce a prototype LDACS receiver that uses Rank-Ordered Absolute Differences (ROAD) statistics for effective interference sensing and employs GAE-enhanced pulse peak processors to mitigate Distance Measuring Equipment (DME) interference. Unlike the current GAE-enhanced pulse peak processors, the proposed methods use ROAD value-based detection for identifying DME interference. The performance of the proposed methods - ROAD GAE enhanced Pulse Peak Attenuator (RGPPA), ROAD GAE enhanced Pulse Peak Limiter (RGPPL), ROAD joint GAE enhanced Pulse Peak Attenuator (RJGPPA), and ROAD joint GAE enhanced Pulse Peak Limiter (RJGPPL) is analyzed across different threshold ROAD values to determine their efficacy in various signal conditions. Moreover, the performance of the proposed methods is compared to existing methods such as conventional pulse blanking and GAE-enhanced nonlinear devices, which use the amplitude of the received signal for the detection of interference. Furthermore, the proposed method's performance is compared to another method, ROAD PB, which uses ROAD statistics to detect DME interference and pulse blanking for DME mitigation. The comparative results show that the proposed methods outperformed conventional pulse blanking and ROADPB. Besides, these methods outperformed existing GAE-enhanced methods for their optimum threshold ROAD value.

Giant and reconfigurable vortical dichroism with multi-layer spiral metamaterials

In the photonics orbital angular momentum dimension, the vortical dichroism (VD) of artificial metamaterials at fixed wavelengths has been extensively investigated. However, the challenges of weak and unregulated VD magnitude still limit the development of chiral optics. Herein, we propose multi-layer spiral metamaterials with phase change material Ge2Sb2Te5 (GST), which support giant VD magnitude of −176% in the optical communication band around 1550 nm. Meanwhile, by changing the temperature to control the GST from crystalline to amorphous states, the VD magnitude rapidly decreases to −1%. This large change from extremely giant magnitude to weak magnitude indicates the advantages of reconfigurable VD response. The maximum modulation depth reaches almost 100%. The GST based metamaterials possess excellent switchable capability for VD magnitude without refabricating structures, which is promising in applications for the next generation of chiral optical communication devices.

Dual-band all-optical logic gate based on coherent control principles

In this paper, we present a dual-band all-optical logic gate based on a coherent perfect absorption metasurface. By utilizing the principle of coherent perfect absorption, we can manipulate the interference between two input signals by adjusting their relative phase difference. This allows us to implement logic functions such as AND, OR, and XOR in the second (1310 nm) and third (1550 nm) windows of the communication band. Moreover, we present the concept of "contrast" as a quantitative metric to assess the performance of each logic gate. The simulation results show that the contrast between the AND gate and the XOR gate can reach 6.4 dB and 17.8 dB at 1310 nm, as well as 6.1 dB and 18.9 dB at 1550 nm, rendering it highly advantageous for practical applications. The realization of ultrafast operation and low power consumption in coherent perfect absorption metasurfaces would significantly contribute to advancing the progress of optical data processing.

Measurement of the effective refractive index of silicon-on-insulator waveguide using Mach–Zehnder interferometers

We propose and demonstrate an accurate method of measuring the effective refractive index of silicon-on-insulator waveguides. By conducting the combined analysis to the troughs’ wavelength in spectra of Mach–Zehnder interferometers on chip. The wavelength-dependent and temperature-dependent effective refractive index of the fabricated waveguides are measured experimentally, and obtained the thermo-optic coefficient of silicon-on-insulator waveguides is about 2×10−4 /℃ in the 1550 nm communication band. The maximum measurement error for effective and group refractive index respectively are 1.5×10−5 and 1.5×10−3 obtained by numerical simulation. And an improved method for taking value of the free spectral range was discussed to obtain a more accurate group refractive index. It proves a fast and lost-cost measurement way to evaluate key optical parameters of waveguide, which can indicate the quality of fabrication process and optimize photonic components.

Unidirectional transmission of optical waveguides in optical communication bands based on the valley Hall effect

Unidirectional transmission of optical waveguides in optical communication bands based on the valley Hall effect

Multi-band ultrathin reflective metasurface for linear and circular polarization conversion in Ku, K, and Ka bands

Linear polarization (LP) and circular polarization (CP) holds paramount importance in Ku, K, and Ka bands for satellite based communication, and remote sensing applications. Satellite based remote sensing applications face challenges like atmospheric attenuation, noise & interference, and signal degradation. Moreover, satellite based communication application demands CP in two distinct, non-adjacent frequency bands with orthogonal polarizations at greater oblique angles, considering the unpredictable incidence angles of electromagnetic (EM) waves. Addressing these challenges, an innovative metasurface polarization converter is proposed to operate efficiently across the Ku-band (13.5–18.0 GHz), K-band (18.0–26.5 GHz), and Ka-band (26.5–38.5 GHz) frequency ranges. The converter achieves left-handed circular polarization (LHCP) in the Ku- and Ka-bands within the frequency ranges of 14.57–15.65 GHz and 27.47–33.85 GHz for y-polarized incident EM waves. Additionally, it provides right-handed circular polarization (RHCP) in the K- and Ka-bands at 17.27–23.92 GHz and 35.87–38.32 GHz for y-polarized incident EM waves. The LP conversion ratio exceeds 95% in the frequency bands of 15.97–16.85 GHz, 24.70–26.65 GHz, and 34.37–35.45 GHz for y-polarized, LHCP, and RHCP incident EM waves, respectively. The metasurface exhibits robust performance up to incidence angles of 45 degrees under oblique conditions. Experimental validation using traditional board-circuit manufacturing demonstrates close agreement between measured co- and cross-polarized reflection coefficients and simulations in the 13.5–18 GHz, and 24–38.5 GHz frequency range. Thin metasurface with a thickness of only 0.64 = 0.013λo mm, the proposed design outperforms existing studies in the literature, establishing its competitive edge in terms of structure and performance.

THz band drone communications with practical antennas: Performance under realistic mobility and misalignment scenarios

For 6G non-terrestrial communications, drones will offer uninterrupted connectivity for surveillance, sensing, and localization. They will also serve as drone base stations to support terrestrial base stations, providing large bandwidth, high-rate, and ultra-reliable low latency services. In this paper, for the first time in the literature, we depict the true performance of Terahertz (THz) band communications among drones by applying various channel selection and power allocation schemes with practical THz antennas within (0.75–4.4) THz under realistic mobility and misalignment scenarios. Through numerical simulations, we unveil the capacity of drone links under different channel selection and power allocation schemes within 10s to 100s of Gbps at distances (1–100) m, when drones are in motion and subject to (mis)alignment due to mobility and even under beam misalignment fading. However, when exposed to real drone mobility traces, the performance of all channel selection schemes drops significantly, sometimes by up to six orders of magnitude, due to the occasional reverse orientations of antennas. In addition to the capacity analysis, we report available frequency bands (transmission windows) considering all schemes and mobility patterns. We also identify a band that is commonly available under all considered mobility and misalignment settings, and we evaluate its performance in terms of spectral and energy efficiencies, which can be useful in designing THz transceivers for drone communications. Our findings emphasize the essence of active beam control solutions to achieve the desired capacity potential of THz drone communications, while also highlighting the challenges of utilizing the THz band for drone communications.

Effect of Ge4+-substituted on the structure characteristics and microwave/terahertz dielectric properties of ultra-low εr, high Q·f cordierite ceramics

In this study, Ge4+-substituted cordierite, Mg2Al4(Si1–xGex)5O18 ceramics, were successfully prepared by the traditional solid-state method to broaden its application potential. Notably, the excellent dielectric properties with εr = 4.90, Q·f = 128,200 GHz, and τf = −21.01 ppm °C–1 were achieved. The increase in εr value is mainly due to the heightened content of Ge4+ with high polarizability. The Q·f value improved by 2.21 times compared to the cordierite matrix, which can be primarily attributed to enhanced lattice energy, bond covalency, and hexagonal ring symmetry. The alteration in τf value arises from the variation of bond energy, bond strength, and distortion in the [MgO6] octahedra. These conclusions provide valuable insights for the design of silicate ceramics with higher Q·f values. In addition, the dielectric properties in the microwave and terahertz bands were compared. The higher Q·f and lower εr values in the terahertz band mainly result from the withdrawal of partial polarization mechanisms and differences in measurement methods. Mg2Al4(Si0.92Ge0.08)5O18 ceramics, demonstrating an ultra-low εr value of 4.54 and an ultra-high Q·f value of 286,533 GHz in the terahertz band, emerge as formidable contenders for future terahertz communications materials. Finally, a microstrip patch antenna was fabricated, achieving a bandwidth of 150 MHz at 4.78 GHz, which confirms the application in the n79 band for wireless communication.

Performance evaluation of vehicular communication in terahertz band

Abstract The Terahertz (THz) band is seen as one of the potentially essential technologies to meet the data throughput requirements of terabits per second (Tbits) in future networks. Considering vehicular communication in particular, the current vehicular communication technologies cannot cope with the rapidly increasing data traffic. To deliver increased capacity and data rate with reduced latency, new technologies and methodologies are therefore required. It is recognized that one possible technology to meet these needs is THz technology. Since the change in distance between vehicles due to their speed affects THz communication, channel modeling was carried out for single-lane and multi-lane vehicular communication scenarios in this study. The system’s performance was also examined. Performance metrics were determined as path loss, signal-to-noise ratio (SNR), capacity and bit error rate (BER). While performing these analyses, the absorption of THz waves is taken into account and the High-Resolution Transmission Molecular Absorption Database (HITRAN) was used to model it. As a result, the most appropriate circumstances for successful vehicular communication have been identified and studied.

A low‐profile four‐degrees of freedom antenna by collocating a ±45°‐polarized dipole and a dual‐polarized microstrip antenna with broadside radiations

AbstractThis letter proposes a novel four‐degrees of freedom (4‐DOFs) antenna for 5.8 GHz wireless local area network band communications. The proposed antenna realizes 4‐DOFs with a low profile (0.11λ), which is composed of ±45°‐polarized dipole (DP), an artificial magnetic conductor (AMC) reflector, and a dual‐polarized slot‐loaded microstrip antenna (MA). The whole size of the proposed antenna is 83 mm × 83 mm × 5.9 mm (1.6λ × 1.6λ × 0.11λ). The DP is printed on the substrate with the wideband characteristic, and the MA operates at TM50 mode. The AMC reflector operating for the DP is designed for the low profile, causing the low isolations between the DP and the MA. The broadside radiation with 4‐DOFs is first reported. The envelope correlation coefficients are lower than 0.07, and the DOFs are 3.75. The measured results are in accord with the simulated results.

Ultra‐Wideband Terahertz Integrated Polarization Multiplexer

AbstractPolarization‐division multiplexing is crucial for increasing channel capacity and spectral efficiency in communications. A key component is the polarization multiplexer, which combines or separates signals with orthogonal polarizations. Existing planar multiplexers lack an ultrawide band for terahertz communications. While microwave‐inspired orthomode transducers (OMTs) provide broadband operation, they suffer from high ohmic loss and bulkiness at terahertz frequencies. Optical integrated polarization beam splitters (PBSs) offer low loss and good integrability but have narrow bandwidths. This work presents a substrateless all‐silicon polarization multiplexer based on tapered directional couplers and air‐silicon effective mediums, integrated monolithically on a compact footprint. The device demonstrates a 37.8% fractional bandwidth, an average insertion loss of 1 dB, and a polarization extinction ratio above 20 dB over 225–330 GHz. This superior performance is enabled by the anisotropy of the effective medium claddings, affecting the two orthogonal guided modes differently. The multiplexer enables simultaneous two‐channel terahertz fiber communications with polarization diversity. It supports aggregated data rates up to 155 and 190 Gbit with bit error rates below hard‐ and soft‐decision forward‐error‐correction limits, respectively. This advancement holds promise for 6G terahertz integrated systems with enhanced channel capacities.

Design of a Compact Multiband Monopole Antenna with MIMO Mutual Coupling Reduction.

In this article, the authors present the design of a compact multiband monopole antenna measuring 30 × 10 × 1.6 mm3, which is aimed at optimizing performance across various communication bands, with a particular focus on Wi-Fi and sub-6G bands. These bands include the 2.4 GHz band, the 3.5 GHz band, and the 5-6 GHz band, ensuring versatility in practical applications. Another important point is that this paper demonstrates effective methods for reducing mutual coupling through two meander slits on the common ground, resembling a defected ground structure (DGS) between two antenna elements. This approach achieves mutual coupling suppression from -6.5 dB and -9 dB to -26 dB and -13 dB at 2.46 GHz and 3.47 GHz, respectively. Simulated and measured results are in good agreement, demonstrating significant improvements in isolation and overall multiple-input multiple-output (MIMO) antenna system performance. This research proposes a compact multiband monopole antenna and demonstrates a method to suppress coupling in multiband antennas, making them suitable for internet of things (IoT) sensor devices and Wi-Fi infrastructure systems.

Design of high flexible multi-band conformal printed patch antenna for sub 6 GHz 5G-based vehicular communication

ABSTRACT Vehicular communications (VCs) play a major role in intelligent transportation systems (ITS). In addition to preventing unintentional collisions and traffic jams, this system can lower fuel and energy usage in the transportation system. The Internet of Vehicles emerges by integrating the IoT with vehicles for smooth communication. In IoV, vehicular communications may be from vehicle to infrastructure (V2I), vehicle to vehicle (V2V), vehicle to pedestrian (V2P), and vehicle to network (V2N) or vehicle to roadside unit (V2R). The antenna used in vehicular communication has some problems, such as less efficiency and high return loss. The frequency response in the existing methods should not give sufficient data for selecting a better band. To avoid this kind of issue and improve the performance by selecting a better frequency band, this work presents a highly flexible multi-band conformal printed patch antenna for sub-6 GHz 5 G-based vehicular communication application. The substrate used to design the antenna is polyimide, and the microstrip patch antenna is designed with cross-shaped slots. The multi-band circularly polarised antenna is designed to operate in vehicular communication bands such as 2.4 GHz, 4.7 GHz, 5.3 GHz, and 5.9 GHz. The proposed work is simulated in HFSS, and the results of directivity, gain, reflection coefficient, Voltage Standing Wave Ratio (VSWR), radiation pattern, axial ratio, Left-Hand Circular Polarisation (LHCP), Right-Hand Circular Polarization (RHCP) and surface current distribution are evaluated for the conformal antenna.