Communication Frequency Band Research Articles

Design and analysis of an energy selective rasorber

Abstract By combining the technique of energy selective surface and frequency selective rasorber, an energy selective rasorber is proposed, which performs selective energy protection in the low communication frequency band (0.8–2 GHz) and wave-absorbing property in the high-frequency band (6–18 GHz). The design consists of two layers, of which the bottom one contains a lumped diode structure for energy selection function in the transmission band, while together with the top layer, they perform a wideband wave absorbing function. The simulated and measured results agree well with each other, and both show good absorption in 6–18 GHz and energy-selective property around 1.86 GHz. That is, when the incident power changes from −30 to 14 dBm, the reflection coefficient changes from below −22 dB to above −2 dB, while the transmission coefficient changes from above −3 dB to below −17 dB.

A compact bent microstrip-based wideband millimeter wave MIMO antenna for 5G applications

Abstract This paper proposes a wideband four-element multiple-input multiple-output (MIMO) antenna operating in the millimeter-wave frequency band for 5G communications from 24.37–39.44 and 45.09–50.62 GHz. The antenna design has been realized using Rogers 5880 substrate and consists of a T-shaped strip that is attached to the top of a 50 Ω feeding line. Two microstrip lines are affixed at the terminal points of T-shaped strip and bent toward the feeding structure. These bent strip lines are then extended by joining two additional L-shaped microstrip lines. On the back, there is a partial defective ground plane featuring a rectangular slot and a thin strip line located at its center. The dimensions of the proposed single element and MIMO antenna are 0.933λ × 0.933λ × 0.024λ and 1.865λ × 1.865λ × 0.024λ, respectively (at 28 GHz), while the edge-to-edge distance between the radiation elements of the MIMO antenna is 4.0 mm. The design incorporates an efficient passive fan-shaped decoupling structure to decrease coupling between antenna elements. Simulations and experimental results show good agreement with each other. For all resonant frequencies the measured peak gain is greater than 4.85 dBi, radiation efficiency is over 90%, diversity gain is greater than 9.5, ECC is less than 0.025, TARC is less than -10 dB and CCL is below 0.4 bits/s/Hz. The proposed MIMO antenna, with its wide bandwidth, high gain, high inter-port isolation, and high efficiency characteristics, can be used for 5G wireless communication applications.

Design of an Ultra-Wideband Transparent Wave Absorber.

In this paper, a multilayer ultra-wideband transparent metamaterial wave absorber is proposed, which has the characteristics of ultra-wideband wave absorption, light transmission and flexible bending; in addition, due to the complete symmetry of the structure, the absorber has polarization insensitivity to incident electromagnetic waves. Both simulation and experimental results show that the frequency range of the microwave absorption rate is higher than 90% between 8.7 GHz and 38.9 GHz (between which most of the absorption rate can reach more than 95%), the total bandwidth is 30.2 GHz, and the relative bandwidth is 126.9%, realizing microwave broadband absorption and covering commonly used communication frequency bands such as X-band, Ku-band, and K-band. A sample was processed and tested. The test results are in good agreement with the results of the theoretical analysis, which proves the correctness of the theoretical analysis. In addition, through the selection and oxidation of indium tin (ITO) materials, the metamaterial also has the characteristics of optical transparency and flexibility, so it has potential application value in the window radar stealth and conformal radar stealth of weapons and equipment.

An ultrawideband antenna with two independently tunable notch bands

This paper presents a planar CPW-fed Ultrawideband (UWB) antenna with two independently tunable notch bands. The proposed design consists of a modified Rhombus-shaped monopole structure that is integrated with a dual band-stop filter based on hexagonal split ring resonators (HSRR). The antenna is capable of suppressing multiple frequency bands within ultrawideband range (3.1–11 GHz) such as WLAN and X-band downlink satellite communication frequency bands with an independent tunable mechanism to fulfill the on-demand band rejection. The frequency reconfigurability of the two notch bands is obtained by loading the hexagonal filter arms with two varactor diodes (for each band). Details of antenna design steps and reconfigurability mechanism are illustrated. The notch band element is explained using equivalent circuit model and surface current distribution at lower and higher notch frequency bands. A prototype of the proposed design is printed on the RO4003C (ϵr = 3.55) substrate printed circuit board (PCB) and tested to authenticate the performance. The proposed antenna volume is 21.5 ▪ 48 ▪ 1.524 mm3 and demonstrates an omnidirectional radiation pattern in E and H planes with an average gain of 3.7 dBi across the operational passbands, while a sharp reduction in gain of -6.8 dBi and -3.5 dBi is achieved at the lower and higher notch bands, respectively. Continuous tuning is achieved experimentally from 5.08 to 5.77 GHz and 7.75 to 8.52 GHz for the lower and higher notch bands, respectively. Excellent agreement is observed between the simulated and measured results. Application areas include radio-frequency identifications, ground-penetrating radar, and wireless communications.

Terahertz Communication with MIMO-OFDM in FANETs for 6G

Background: Unmanned aerial vehicles (UAVs) are envisioned in several intelligent transport system (ITS) application fields due to their autonomous operation, mobility, and communication/processing capabilities. Methods: In order to increase performance, dependability, and customer satisfaction, wireless communications are being used for essential and noncritical services in a variety of transportation systems. Terahertz (THz) communication aims to raise the wireless communication frequency band to the terahertz level and is one of the technologies that shows the most promise in addressing needs like the exponential increase in the number of devices, the necessity for higher data rates, and the need for larger channel capacity. For meeting the demands of 5G and 6G users, the hybrid combination of multiple input multiple output (MIMO) and orthogonal frequency division multiplexing (OFDM) appears to be an excellent technology. Therefore, it is essential to investigate the performance of THz communication with MIMO-OFDM in flying ad hoc networks (FANETs) for 6G. FANETs are multi-UAV systems arranged in an ad hoc way. Results: In this paper, the performance of the THz communication with MIMO-OFDM in FANETs for 6G is evaluated. The Markov chain model-based analytical study is used to derive how parameters and performance measures relate to one another. Conclusion: The equations for path loss, outage probability, bit error rate, and throughput are attained. Moreover, numerical results are shown to justify the outcomes of the analytical studies.

NR5G-SAM: A SLAM Framework for Field Robot Applications Based on 5G New Radio.

Robot localization is a crucial task in robotic systems and is a pre-requisite for navigation. In outdoor environments, Global Navigation Satellite Systems (GNSS) have aided towards this direction, alongside laser and visual sensing. Despite their application in the field, GNSS suffers from limited availability in dense urban and rural environments. Light Detection and Ranging (LiDAR), inertial and visual methods are also prone to drift and can be susceptible to outliers due to environmental changes and illumination conditions. In this work, we propose a cellular Simultaneous Localization and Mapping (SLAM) framework based on 5G New Radio (NR) signals and inertial measurements for mobile robot localization with several gNodeB stations. The method outputs the pose of the robot along with a radio signal map based on the Received Signal Strength Indicator (RSSI) measurements for correction purposes. We then perform benchmarking against LiDAR-Inertial Odometry Smoothing and Mapping (LIO-SAM), a state-of-the-art LiDAR SLAM method, comparing performance via a simulator ground truth reference. Two experimental setups are presented and discussed using the sub-6 GHz and mmWave frequency bands for communication, while the transmission is based on down-link (DL) signals. Our results show that 5G positioning can be utilized for radio SLAM, providing increased robustness in outdoor environments and demonstrating its potential to assist in robot localization, as an additional absolute source of information when LiDAR methods fail and GNSS data is unreliable.

A wideband CMOS LNA using noise‐canceling topology and gm‐boosting technique

AbstractIn this letter, a wideband low noise amplifier (LNA) using noise‐canceling topology and gm‐boosting technique is proposed. The noise‐canceling topology is used in the common gate (CG) amplifier to achieved better noise figure (NF) and wideband input matching. Meanwhile, the requirement of the input transconductance can be obviously decreased due to the application of gm‐boosting technique, which effectively alleviate the trade‐off between power consumption and voltage gain. The 3‐dB bandwidth of the LNA is from 2.1 to 4.1 GHz, covering widely used 5 G wireless communication frequency bands (n1, n7, n38, n41, n66, and n78 bands). The proposed LNA shows a flat and low measured NF of 3.3–3.6 dB within the operating bandwidth, while the peak power gain is 18.7 dB. The power consumption of this circuit is 16 mW with 1.2 V supply voltage, and the core area of the circuit is 0.066 mm2 with only one inductor for the whole chip.

A Multi-Frequency Omnidirectional Antenna Based on a Ring-Shaped Structure.

A multi-frequency microstrip antenna loaded with a ring-like structure has been proposed. The radiating patch on the antenna surface consists of three split-ring resonator structures, and the ground plate consists of a bottom metal strip and three ring-shaped metals with regular cuts to form a defective ground structure. The proposed antenna works in six different frequency bands covering 1.10, 1.33, 1.63, 1.97, 2.08, and 2.69 GHz and works entirely when connected to 5G NR (FR1, 0.45-3 GHz), 4GLTE (1.6265-1.6605 GHz), Personal Communication System (1.85-1.99 GHz), Universal Mobile Telecommunications System (1.92-2.176 GHz), WiMAX (2.5-2.69 GHz), and other communications frequency bands. Moreover, such antennas also have stable omnidirectional radiation properties across different operating frequency bands. This antenna meets the needs of portable multi-frequency mobile devices and provides a theoretical approach for the development of multi-frequency antennas.

A High-gain, Low-profile Filtering Antenna Based on a Novel Metasurface

In this paper, a filtering antenna based on a metasurface is designed using slot-coupled feeding, and the metasurface unit is a fractal pattern. Replacing the rectangular patch on the metasurface with a fractal patch can introduce a radiation zero point on the upper sideband of the antenna, thereby enhancing the sideband selectivity. In addition, the current is reversed by loading shorting pin, and a radiation zero point is also introduced in the lower sideband. After measurement, the -10 dB impedance bandwidth of the filtering antenna is 23.6% (3.22-4.08 GHz), and the average antenna gain in the passband is 8.1 dBi. The filtering antenna does not involve an additional filter circuit, has a simple structure, and a small size, and ideally eliminates insertion loss. To verify, the real object was made and tested and found that the reflection coefficient, pattern, gain, etc. were in good agreement with the simulation results, it can be applied to the 5G communication frequency band.

Performance Analysis and Power Allocation for Cooperative ISAC Networks

To mitigate the overlapping of the radar and communication frequency bands caused by large-scale devices access, we propose a novel integrated sensing and communication (ISAC) system, where a micro base station (MiBS) simultaneously carries out both target sensing and cooperative communication. Concretely, the MiBS, acting as the sensing equipment, can also serve as a full-duplex decode-and-forward relay to assist end-to-end communication. Moreover, nonorthogonal downlink transmission (NO-DLT) is adopted between the macro base station and the Internet of Things devices, so that the spectrum utilization can be further improved. To facilitate the performance evaluation, both the exact and asymptotic outage probabilities, the ergodic rates associated communication, and the probability of successful sensing detection are characterized. Subsequently, a pair of problems of maximizing the receive signal-to-interference-plus-noise ratio of the sensing signal and maximizing the sum rate of communication are formulated that are solved by the classic Lagrangian method while exploiting the associated function monotonicity. Our simulation results demonstrate that: 1) The proposed ISAC NO-DLT system improves both the communication and sensing performance under the same power consumption as noncooperative NO-DLT and 2) the proposed power allocation (PA) schemes are superior to the random PA scheme.

High isolation 4‐port MIMO sloted antenna for Sub‐6 GHz wireless applications

AbstractAiming at the application of Sub‐6 GHz band, this paper presents a high isolation four‐port MIMO slot antenna with CPW feeding mode. About this antenna, two parallel binary antennas are oppositely arranged with connected ground, and isolation branches are adopted to improve isolation. Each element antenna is realized through elliptical shape patch and trident structure feed line. The measured results show that its working frequency band is 1.82–6.5 GHz band, with ports isolation less than −20 dB. In addition, its other performance parameters are good, such as gain of 7.03 dB and ECC parameter below 0.004, and CCL is less than 0.3 bps/Hz. The antenna has high isolation and it can not only work in the mobile communication frequency bands such as n41, n77, n78, and n79, but also work in the frequency band of the IoT, such as WiFi5, V2X, and DSRC.

Mathematical Channel Modeling of Electromagnetic Waves in Biological Tissues for Wireless Body Communication

In the wireless body area network (WBAN), radio propagations from devices that communicate with the human body are very complex and distinctive compared to other environments. As we know, the human body is a lossy channel that significantly attenuates the propagation of electromagnetic waves (EMW). Therefore, channel models are critical in evaluating the communication link. One of the most predominant models is the path loss channel model, which is used to cover a wide range of communication channels and frequency bands in WBAN. This paper investigates the EMW in a human model irradiated by an incident electromagnetic plane wave. A planar multilayer structure is used for modeling human tissue. Moreover, the steady-state electromagnetic distribution is calculated by solving the differential and integral equations (DIE) by using the method of moments (MoM). The obtained results demonstrate the great use of performing a theoretical analysis for path loss (PL) and power loss density (PLD) estimation. The magnitude of the electric field inside muscle tissue at various depths, and with the most important frequencies in medical applications, is evaluated. This investigation provides evidence that the penetration of EMW in biological tissue strongly depends on the frequency and thickness of the tissue involved. Thus, for different examined conditions, an excellent agreement between recent results that were obtained by an analytical method, finite element (FEM), and the proposed MoM method is verified to be valid in this investigation, and it is found that the distribution of the field, PL, and PLD for different communication scenarios is very promising to determine the quality of communication for WBAN technology.

Ultrawideband Shared-Aperture Crossed Tapered Slot Antenna for 5G Applications

A shared aperture scheme based on a tapered slot configuration is proposed in this letter. The main structure of the proposed antenna is an ultrawideband (UWB) crossed tapered slot with ground. In order to improve the practicality, four 1 × 4 dipole arrays containing feeding networks in the millimeter-wave (mm-wave) band are embedded in the four arms of the crossed tapered slot antenna. Four metal reflectors (or flares) are introduced to increase the gain of the dipole array. Owing to the ultrawideband characteristics of the tapered slot antenna, the proposed slot antenna can cover most sub-6 GHz communication frequency bands (such as LTE bands, N77–N79 bands, etc.). The proposed antenna has a compact volume of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$0.5 \lambda \times 0.5 \lambda \times 0.38 \lambda$</tex-math></inline-formula> , where λ is the free-space wavelength at 1.5 GHz. A prototype is designed, fabricated and tested. The measured results show that a −10 dB impedance bandwidth of 107% (1.5–5 GHz) and 15.8% (25–29.3 GHz) is realized in the sub-6 GHz band and mm-wave band, respectively. The isolation between all ports is higher than 30 dB. The gain variation of the antenna in the low-frequency range is 3.8–7.8 dBi. The peak gain of a single dipole array is approximately 14 dBi. The proposed antenna has the characteristics of shared aperture, low cost, and UWB, which is suitable for 5G microbase station applications.

Design of Triple-Band (DSRC, 5G, 6G) Antenna for Autonomous Vehicle Telematics

A triple-band stacked-patch antenna covering dedicated short-range communication (DSRC), fifth-generation (5G) millimeter-wave, and sixth-generation (6G) millimeter-wave frequency bands is reported for autonomous vehicles telematics applications. To show the effectiveness of the developed antenna, the antenna performances, such as the S-parameter, realized gain at boresight, and radiation patterns were simulated and measured for DSRC and 5G, and only simulated for 6G. The simulated results show good agreement with the measured results. The results show that the developed triple-band antenna can cover all three bands with high peak realized gains of 6.87 dBi, 12.3 dBi, and 19.8 dBi at DSRC, 5G, and 6G frequency bands, respectively, as well as high isolation between ports of &gt;20 dB. The results also show a straightforward structure and higher antenna gain than the previously reported triple-band antennas in the simulation level.

Artificial neural network optimized ultra wide band fractal antenna for vehicular communication applications

AbstractThe article proposes a microstrip patch antenna for vehicular communication applications under 5G communication frequency band. The dimensions of the antenna play an important role in the field of vehicular communication applications. The antenna dimensions are optimized by introducing back propagation algorithm. Overall dimension of the antenna is reduced by 16% as compare to the traditional formulations. Further fractal geometry is implemented on the patch and recessed ground as defected ground structure. FR4 epoxy is used to construct the substrate of the proposed antenna with the dimensions of 50 mm × 60 mm × 1.6 mm and the patch is designed as rectangular patch with H‐cut and I‐cut. The proposed antenna is simulated using Ansys high frequency structure simulator v15 and the frequency of operation is 27 to 33 GHz. The antenna parameters such as reflection coefficient, voltage standing wave ratio, gain, radiation, and current distribution are investigated. The antenna is designed in compact in shape such that it is suitable for vehicular communication applications.

Design and Fabrication of Temperature-Compensated Film Bulk Acoustic Resonator Filter Based on the Stress Compensation Effect

To ensure that the performance of filters matches the continuous development in communication frequency bands, the influence of temperature on filter performance must be considered during the fabrication of filters. In this study, a cavity-type temperature-compensated film bulk acoustic resonator (TC-FBAR) device was prepared with an SiO2 temperature filter between the bottom electrode and the piezoelectric layer. A one-dimensional Mason model of the TC-FBAR was established. An advanced design system, a high-frequency structure simulator, and COMSOL software were used to optimize the design of the TC-FBAR. After the optimization, the out-of-band rejection was improved by 10 dB. To address the compensation effect of the tensile and compressive stresses, a multilayer film was implemented for low-stress control and a reduction in stress to |P| ≤ 150 MPa, thereby improving the orientation of the piezoelectric film. Moreover, the influence of the thickness of the SiO2 temperature-compensated layers on the temperature-compensated characteristics was studied. When the SiO2 thickness was 50 nm, the temperature coefficient of frequency (TCF) was ±1 ppm/°C. The center frequency and 3 dB bandwidth of TC-FBAR were 2.492 GHz and 15.02 MHz, respectively, and the center insertion loss was −3.1 dB. Moreover, the out-of-band rejection was greater than 40 dBc, and TCF was 0.8 ppm/°C.

Islands of Connectivity [communications - networks and services

Stunning coastlines and verdant mountain scenery make the Cook Islands a popular tourist destination. This tourism industry has contributed to a decade of economic growth, and in 2021 the government of this nation in the South Pacific introduced the SMART Economy Initiative to create &apos;smart&apos; island networks. Around the world, the Internet of Things (IoT) is used for energy metering, road traffic management, street lighting operation and environmental controls. Not all IoT nodes need the fast data transfer of a 5G network, and in the Cook Islands, the tropical and mountainous terrain means installation is not practical. LoRaWAN (long-range wide area network) technology was selected for the Cook Islands&apos; Smart Island project. The low-power protocol uses the unlicensed industrial, scientific, and medical (ISM) frequency band for bi-directional communication.

Pattern-Reconfigurable Liquid Metal Magneto-Electric Dipole Antenna

We propose a pattern-reconfigurable liquid metal magneto-electric dipole antenna. The antenna is composed of a magneto-electric dipole made of copper and a liquid metal channel structure made of Polycarbonate (PC), one Г-Type feeding strip is placed in the middle of magneto-electric dipole for coupling feeding. The proposed pattern-reconfigurable antenna mainly uses liquid metal to make parasitic units around the antenna. Each liquid metal parasitic unit is controlled separately and connected with the liquid storage tank at the bottom through a plastic tube, by changing the arrangement of parasitic units, the pattern reconfiguration of 15 states can be realized corresponding to (θ, Φ) max = (0°, 0°), (±32°, 0°), (±30°, ±30°), (±32°, ±58°), (±28°, ±86°). The main working frequency band of the antenna is 2–2.5 GHz. When the working state of the antenna changes, the gain is always higher than 6 dB and the efficiency is greater than 70%. The proposed antenna can cover part of the communication frequency band and can be used for future communication.

Design and implementation of a bioinspired leaf shaped hybrid rectenna as a green energy manufacturing concept

In this communication, the novel low cost hybrid energy harvester combining rectifying antenna with the solar cell for feeding the low power energy systems are reported. The bioinspired leaf shaped monopole antenna is designed to work in the most used communication frequency bands such as GSM-1800, UMTS-2100, WIFI-2.45 and LTE-2.65 GHz for the energy harvesting purposes and microstrip low pass filter is also added on the feeding line for the second harmonic rejection for increasing the efficiency of the harvester. The solar cell is placed on the ground plane of the designed leaf shaped antenna for using volumetric space efficiently and obtain a more compact system. The implemented prototype harvester generate 76 mV, 120 mV and 90 mV when the same type receiver antenna feed from the 25 dBm power from the RF source located at a distance of 1 m which satisfies the far field condition of the antenna without solar cell at the 2.15 GHz, 2.45 GHz and 2.65 GHz frequency bands, respectively. After the illumination of its solar cell component with 165 lux, the total harvested voltages are measured as 150 mV, 170 mV and 190 mV at the same frequency bands, respectively.

Stretchable and Dynamically Tunable Attenuator Based on Graphene

In this article, a flexible, stretchable, and dynamically tunable attenuator based on coplanar waveguide (CPW) and graphene is proposed. Soft silicone elastomer and serpentine metal structure are used to realize the flexible, stretchable, and biocompatible characteristics of the CPW. A graphene sandwich structure (GSS) is placed on the upper surface of the CPW to dissipate the electromagnetic wave, achieving the dynamically adjustable characteristics of the stretchable attenuator. When the surface impedance of the GSS is tuned by applying a proper bias voltage, the simulated and measured results reveal that the attenuation tuning range is dynamically tuned from 4–11 dB with a low reflection below −10 dB. In addition, the fabricated attenuator is simultaneously optimized to work at conditions of the normal state, 180° bending and 130% stretching, with acceptable changes between insertion loss and return loss up to 6 GHz. The attenuator covers the medical frequency band of 2.4–2.483 GHz and the 5th generation (5G) communication frequency band of 3.5–3.8 GHz, which demonstrates that the attenuator has potential applications in stretchable electronic systems.