GHz Band Research Articles

Doping LaNiO3 perovskite with Ba for defect-steered microwave absorption

LaNiO3 is considered electromagnetic wave-absorbing material owing to its unique crystal structure and controllable dielectric constant. However, the effect of ion doping modification on microwave absorption performance remains to be thoroughly investigated. In this study, LaNi1−xBaxO3(x = 0, 0.02, 0.04, 0.06) was prepared through sol-gel methods. The reflection loss (RL) of the sample in the 2−18 GHz band was calculated using transmission line theory. Specifically, LaNi0.96Ba0.04O3 exhibited superior results, with an RL value of −34.54 dB at d = 3 mm and f = 6.80 GHz, indicating effective absorption within the C-band. These results suggest that adding an appropriate amount of Ba ions to the material can effectively regulate the electromagnetic parameters and optimize impedance matching. Introducing Ba ions into the crystal interior produces abundant defects, which provide active sites for multipolarization and ultimately improve the wave-absorbing properties of the material. In addition, radar cross section(RCS) simulations simulation after coating the samples on original ideal conductor (PEC) substrates provide support for potential practical applications of the material.

Sensing Using Terahertz Radiation

Terahertz (THz) sensing technology enables 6G communication, detection of biological and chemical hazardous agents, cancer detection, monitoring of industrial processes and products, and detection of mines and explosives. THz sensors support security in buildings, airports, and other public spaces. They found important applications in radioastronomy and space research and, more recently, in Artificial Intelligence-driven THz sensing of MMICs and VLSI. Exploding demand for data transfers will require using the 300 GHz band after 2028 or even before and will make the deployment of THz sensing electronics inevitable. This paper discusses the new physics of THz sensing and THz sensing devices. It also reviews the THz sensing market, and key THz sensor companies.

Advances in High–Speed, High–Power Photodiodes: From Fundamentals to Applications

High–speed, high–power photodiodes play a key role in wireless communication systems for the generation of millimeter wave (MMW) and terahertz (THz) waves based on photonics–based techniques. Uni–traveling–photodiode (UTC–PD) is an excellent candidate, not only meeting the above–mentioned requirements of broadband (3 GHz~1 THz) and high–frequency operation, but also exhibiting the high output power over mW–level at the 300 GHz band. This paper reviews the fundamentals of high–speed, high–power photodiodes, mirror–reflected photodiodes, microstructure photodiodes, photodiode–integrated devices, the related equivalent circuits, and design considerations. Those characteristics of photodiodes and the related photonic–based devices are analyzed and reviewed with comparisons in detail, which provides a new path for these devices with applications in short–range wireless communications in 6G and beyond.

Dual-band MIMO antenna with low mutual coupling for 2.4/5.8 GHz communication and wearable technologies.

To satisfy the requirements of modern communication systems and wearables using 2.4/5.8 GHz band this paper presents a simple, compact, and dual-band solution. The antenna is extracted from a circular monopole by inserting various patches and stubs. The genetic algorithm is utilized to optimize the parameters and achieve the best possible results regarding bandwidth and gain. Afterward, a 2-port multiple-input-multiple-output (MIMO) configuration is created by positioning an identical second single element perpendicularly to the first one. The electrical size of the suggested MIMO configuration is 0.26 λL × 0.53 λL, where λL represents the free space wavelength at lower resonance of 2.45 GHz. The common ground technique is adopted to further reduce and achieve the accepted level of mutual coupling of the MIMO configuration. The presented MIMO antenna offers a low mutual coupling of < -27 dB with 0.2 envelope correlation coefficient (ECC). The antenna has a gain of around 6.2 dBi and 6.5 dBi at resonating frequencies of 2.45 GHz and 5.4 GHz. Furthermore, the specific absorption rate (SAR) analysis of the MIMO antenna offers a range inside of the standard values, showing its potential for On/Off body communications. The comparison with already published works shows that the proposed antenna achieves better results in either compact size or wide operational bandwidth along with low mutual coupling.

Multifunctional titanium co-doped ZnAl2O4V2O5 composite ceramic nanoparticles: Enabling enhanced performance for L, S, C, and X band communications

This paper investigates the potential of zinc aluminate (ZnAl2O4)-based microwave dielectric ceramics for use as materials in the 4–10 GHz band for patch antennas. Microwave dielectric nanoceramics (MDNC) play a vital role in the telecommunications industry, and ZnAl2O4 stands out as a particularly intriguing and promising nonmetal for wireless microstrip antennas. X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) assessments confirm the presence of both ZnAl2O4 and TiO2/V2O5, establishing a dual-phase system. Simultaneously, energy dispersive spectroscopy (EDS) is utilized to scrutinize the composite nanoparticles for functional groups, morphology, and elemental composition. The introduction of titanium dioxide/vanadium pentoxide results in a significant augmentation of both crystallite and grain sizes. The estimated size of the nanoparticles' crystallites is 19 nm, while the dielectric permittivity and dielectric loss range between 22.82 and 22, and 0.14 and 0.007, respectively. This paper presents the key parameters of the fabricated patch antenna, denoted as (1-x)ZnAl2O4x(0.6 wt%V2O5-0.4 wt%TiO2) (ZAVT). The antenna's performance is defined by a return loss (RL) of −44.69 dB, a bandwidth spanning 1.723 GHz, and a voltage standing wave ratio (VSWR) of 1.23, all observed consistently at an operational frequency of 8.73 GHz in both measured and simulated scenarios.

Optimal channel selection for tri-band Wi-Fi in a residential scenario

The growing use of Internet of Things devices and the increasing demand for high-speed, reliable, and secure wireless connectivity pose significant challenges for existing wireless networking solutions in modern smart homes. As such, there is an increasing urgency for the development of advanced and effective wireless technologies that can fulfil the new requirements for interconnected devices and services deployed in households. Tri-band Wi-Fi 6E equipment addresses these needs by reducing the network congestion and enhancing the performance across the 2.4 GHz, 5 GHz, and 6 GHz bands. However, improper band management can lead to frequent interference and network issues. As such, this work introduces a dynamic Wi-Fi link orchestration solution that follows a heuristic model. This approach aims to optimize the network layout and channel allocation based on device metrics, utilizing the EasyMesh specification for simplified network setup and management. The model was implemented and tested in a residential environment network, using EasyMesh and tri-band Wi-Fi 6E devices. Results show the effectiveness of the model in improving network capacity and adapting the links to the current traffic, outperforming the initial and base network configuration.

Dual-Band 2 × 1 Monopole Antenna Array and Its MIMO Configuration for WiMAX, Sub-6 GHz, and Sub-7 GHz Applications

This study introduces a cost-effective monopole antenna array and its MIMO configuration. The single element consists of a rectangular patch monopole featuring five circular slots at the center, accompanied by two thin slots at the top, offering a wide bandwidth (2–7.62 GHz) and a peak gain of 3.8 dBi. For gain improvement, a 2 × 1 antenna array is demonstrated. This antenna array exhibits dual-band behavior; spans from 2 to 3.71 GHz and from 5.9 to 7.54 GHz; covers the 2.5 GHz band (2.3–2.7 GHz), a significant portion of the n78 band (3.3–3.71 GHz), and the n96 band (5.925–7.125 GHz); and is assigned to WiMAX, sub-6 GHz, and sub-7 GHz applications, respectively. The antenna array achieves a peak gain of 6.47 dBi. Lastly, a two-element MIMO configuration derived from the 2 × 1 array is designed. Implementing a defected ground structure (DGS) on the ground plane plays a crucial role in enhancing the isolation from 7 dB to 20 dB. The presented MIMO antenna covers the desired frequency bands of 2.5 GHz, n78, and n96 with a peak gain of 7.5 dBi and high radiation efficiency (&lt;99%), which qualifies it for WiMAX, sub-6 GHz, and sub-7 GHz applications.

Preparation and electromagnetic waves absorption performance of hibiscus-like CuS/SiC NWs@PANI in the GHz band

With the increasing demand for electromagnetic (EM) waves absorbing materials in communication, military, and electronic devices, the exploration of lightweight, wideband, and highly absorptive materials in the GHz frequency range has become urgent. This article presents a successful synthesis of hibiscus-like copper sulfide (CuS)/silicon carbide nanowires (SiC NWs) @polyaniline (PANI) composite material using a combination of hydrothermal and in-situ polymerization techniques. With a filling amount of only 25 wt% of CuS/SiC NWs@PANI in the paraffin transmissive matrix, the material exhibits a minimum reflection loss (RLmin) of −31.6 dB at a thickness of 2.1 mm, while providing an effective absorption bandwidth (EAB) of 4.5 GHz. As the filling amount increases to 35 wt%, the RLmin drastically reduces to −41.38 dB at a thickness of 2.3 mm. The CuS particles exhibit a unique multi-layered asymmetric hibiscus-like structure, which greatly enhances the reflection of EM waves. The conductive polymer PANI, forming a coating layer at the interface with CuS and SiC NWs, effectively enhances the conductive loss. The collaborative interactions among the components in the ternary composite material significantly boost the EM waves absorption performance. This article offers valuable insights into the preparation and real-world application of absorbent materials with distinctive microstructures, thus opening up new avenues for the design of composite absorbing materials.

Concept and Design of a Multi-Polarization Reconfigurable Microstrip Antenna with Symmetrical Biasing Control.

Wireless communication systems have grown rapidly, moving towards being highly compact, intelligent, and flexible to adapt to changing operating requirements. Multifunctional and highly versatile antennas are key in this development to ensure system quality. Reconfigurable antennas, particularly regarding polarization, allow frequency reuse and enable the mitigation of fading effects. This work presents a square microstrip patch antenna operating in the ISM 5.8 GHz band with reconfigurable polarization by controlling its feeding. This antenna has four different states through the application of a symmetrical DC voltage that controls an RF circuit with PIN diodes. As a result, the microstrip patch can operate with three different polarizations: linear polarization and both circular polarizations (right-handed and left-handed). The antenna was fabricated to validate the proposed concept. The good agreement between the measurement and the simulation results was possible to observe regarding its polarization behaviour, impedance adaptation and radiation pattern.

A compact circularly polarized dual port MIMO antenna with DGS and parasitic patch for modern wireless communication and IOT applications

Abstract The article proposes a broadband dual-port planar multiple-input-multiple-output (MIMO) antenna for the lower sub-6 GHz band (1.67 GHz to 3.15 GHz) applications. The simple structure of the MIMO antenna system consists of a semi-annular ring-shaped patch with a covering cap-like structure connected with two symmetrical L-shaped structures. A partial ground with a rectangular mesh-like structure at the center is designed and the same rectangular mesh has been added as the parasitic element with the driven patch to attain circular polarization and enhanced isolation. The miniaturized dimensions of the two-port MIMO antenna system are 0.28 λ 0 × 0.54 λ 0. The suggested two-port MIMO antenna offers a wider impedance bandwidth (IBW) of 61.41% around the versatile resonant frequency of 2.4 GHz. The proposed MIMO also depicts a minimum isolation of 26 dB with an edge-to-edge spacing of 0.19 λ 0. An axial ratio bandwidth of 280 MHz is attained between 2.36 GHz and 2.64 GHz. The proposed antenna shows good IBW with excellent isolation, along with good radiation and MIMO diversity characteristics to operate at 2.4 GHz with circular polarization. The designed MIMO antenna can be utilized for IoT and modern mobile wireless applications as the broad bandwidth covers various IoT communication protocol frequencies such as 1.8 GHz (NB-IoT) and 2.4 GHz (Wireless LAN).

Elliptical Multi Orbital Truncated Flexible Patch Antenna Using PDMS Substrate for Sub 6 GHz Applications

This paper presents an elliptical-shaped multi-orbital truncated patch antenna applicable forsub-6 GHz bands. The sub-6 GHz bands cover 5.8 GHz high-speed wireless communication. The antenna is designed on a Poly Dimethylsiloxane (PDMS) substrate. PDMS is used for designing the proposed antenna. It is a flexible substrate with a dielectric constant εr value of 2.7 and a loss tangent tan δ value of 0.022. The substrate dimension is 20×15×1.6 mm3in which a patch is created with the size of 12.5×13 mm2. The proposed antenna resonates at 6.2 GHz showing a reflection coefficient (s11) value of -37 dB. The impedance bandwidth of the antenna is 1.225 GHz in the range of 5.5-6.725 GHz frequency, and the maximum peak gain is about 3.5 dB. The proposed antenna is simulated, fabricated, and experimentally tested.

Dual-Band Millimeter-Wave MIMO Antennas For 5G Wireless Implementation

For 5G wireless applications, this exploration proposes a dual-band 28/38 GHz 4-component MIMO array depending on duplex-mode planar monopole antennas. Four planar monopole antennas are part of the layout framework, situated at the districts of a Rogers RO4003 substrate measuring 20 by 20 mm2 and with a dielectric constant of 3.55. The form of the suggested placoid monopole antenna is crescent-shaped. We created a notch at the bottom and inscribed two rectangular holes on each side to get the required behaviour and execution. For enhancement of isolation, we also employed a limited ground plane. Antenna elements can achieve significant isolation (&gt; − 23 dB) using spatial and scattering behaviour approaches. A illustration of the four-element MIMO array is created, manufactured, and measured to multifariousness the outline idea. The investigational outcomes demonstrate that the suggested antenna has strong isolation and high efficiency while covering the 27.25–29 GHz and 34.5–41 GHz bands. Additionally, studies are done on the channel capacity, realized gain, and radiation pattern. The obtained findings suggest that, for millimeter-wave 5G MIMO implementation, the proposed MIMO antenna might be an excellent application-oriented design.

A dual‐wideband 5G antenna with dual polarization in the sub‐6 GHz band and 2 × 2 MIMO function in the 28‐GHz band

AbstractA novel aperture‐shared dual‐wideband 5G antenna with dual polarization in the sub‐6 GHz band and multi‐input multi‐output (MIMO) function in the 28‐GHz band is presented in this work. A dual‐polarized megnetoelectric dipole (ME‐dipole) with wide bandwidth is introduced in the sub‐6 GHz band. Based on the partial structure reuse method, four 2 × 2 substrate integrated waveguide (SIW) cavity‐backed patch arrays are integrated into the electric dipole structure of the ME‐dipole to construct a 28‐GHz 2 × 2 MIMO system. Two high‐order SIW cavity modes that cooperate with patch modes are used to enhance bandwidth in the 28‐GHz band. For demonstration, a prototype of the proposed antenna was fabricated and measured. The simulated results are in good agreement with the measured results, showing wide bandwidths of 39.6% and 10.85% in the sub‐6 GHz and the 28‐GHz bands, respectively. In addition, excellent measured in‐band and cross‐band isolations of over 44.4 dB and 45.2 dB are obtained, respectively.

Mutual coupling reduction between antennas array for 5G mobile applications

This paper introduces the design of a multiple-input-multiple-output (MIMO) antenna optimized for low-profile applications supporting sub-6 GHz fifth-generation (5G) wireless applications. We have started the design from a single antenna with a square patch shape, each antenna array is composed from 4-element radiators fed by using power dividers and quarter microstrip lines. Mounted on a single Rogers RT5880 substrate, the MIMO antenna functions at 3.5 GHz. In order to miniature and to decrease the mutual coupling between the both antennas array we have optimised a magnetic wall based on periodic structures permitting to decrease the mutual coupling between the both antenna array. The unit element from the wall was optimised, studied and validated in order to absorb the surface current and to enhance the isolation between the different radiating elements. The dimensions of the proposed MIMO antenna are 154×220×0.578 mm³. The MIMO antenna final circuit achieves a peak gain of 9 dBi and an isolation around -30 dB. The introduction of the magnetic wall permits to enhance the isolation between the antenna array from -20 dB to -30 dB at 3.5 GHz band. This advancement contributes to the overall performance improvement of the MIMO antenna system.

A Terahertz GaN solid‐state power amplifier on radial combining technique

AbstractTerahertz (THz) bands are considered to have various anticipated applications. Output power is an important factor determining the operating distance of THz systems, but it is very challenging to achieve high output power under current solid‐state terahertz circuit technology. The paper first presents a four‐way G‐band radial combiner, which features high passive efficiency of 88% and compact size. Moreover, based on this radial combiner and in‐house fabricated gallium nitride chips, a solid‐state power amplifier prototype is further demonstrated. Measured results show that, the average saturated output power is 21.7 dBm across the 180–240 GHz band with a typical output power of 23.2 dBm at 189 GHz.

Demonstration of THz frequency hopping in the 300 GHz band based on UTC-PD and tunable DFB laser array

We explored the potential of an optoelectronic frequency hopping system within the 300 GHz band, leveraging a tunable distributed feedback laser array and uni-traveling carrier photodiode. Our experiments successfully achieved a 10-channel terahertz (THz) frequency hopping, marking a significant advancement in THz secure communication technologies. Notably, the system exhibited a rapid frequency-hopping capability with a short transition time of 0.8 ms between channels, ranging from 288 to 331 GHz. Further, we conducted data transmission tests at a rate of 5 Gbit s−1 across several channels. The results were promising, showing each channel maintained a clear eye pattern and a low bit error rate, crucial factors for reliable and secure data transmission. These findings not only demonstrate the efficacy of our system but also open new avenues for high-speed, secure THz communication.

Channel Measurements and Modeling of Wooded Hilly Terrain At Sub-1 GHz Band

Channel Measurements and Modeling of Wooded Hilly Terrain At Sub-1 GHz Band

Non-volatile voltage-controlled magnetization in single-phase multiferroic ceramics at room temperature

Single-phase multiferroics (MFs) exhibiting ferroelectricity and ferromagnetism and the strong magnetoelectric (ME) coupling effect at room temperature are seen as key to the development of the next-generation of spintronic devices, multi-state memories, logic devices and sensors. Herein, the single-tetragonal phase (1–x) (Sr0·3Bi0·35Na0·329Li0.021)TiO3-xBiFeO3 (x = 0.2 or 0.4) system was designed to study the intrinsic ME coupling effect at room temperature and high frequencies. The polarization arises from the cooperative displacement of both Fe3+ and Ti4+ relative to the oxygen sublattice in the tetragonally distorted perovskite structure, and the magnetization stems from indirect exchange magnetic interaction between adjacent iron ions. A switchable voltage-controlled magnetization was confirmed by a change of the coercive magnetic field, Hc, and remnant magnetization, Mr, in the x = 0.4 component subjected to an external electric field at room temperature and was possibly attributed to a strain-mediated ME coupling effect. In addition, resonance behaviours of the complex magnetic permeability and complex dielectric permittivity in the GHz band indicate that this ME effect is intrinsic in nature and could broaden the applications of multiferroics to devices operating at microwave frequencies.

A Simultaneously Transmit and Receive Antenna Terminal for In-Band Full-Duplex Applications

In this paper, a low-profile co-linearly polarized simultaneously transmit-receive antenna (STRA) terminal is presented for 5G and upcoming technologies. The proposed STRA terminal comprises of an identical pair of spatially rotated half-circular microstrip antennas for transmission (Tx) and reception (Rx). The challenge of self-interference (SI) is addressed by employing passive SI cancellation techniques such as spatial diversity, field confinement, and surface perturbations. This has been accomplished by using fence-strip structure and V-shaped slots in the ground plane. The STRA was designed, fabricated, and tested for full-duplex operation in a sub-6 GHz band lying from 5.73 to 5.88 GHz, providing high interport isolation ranging from 35.5 dB to a maximum of 46.5 dB. The proposed STRA was implemented using Rogers 3003™ substrate. The measurements yield radiation characteristics with high gain of 5.45-6.0 dBi and 5-6.5 dBi for Tx and Rx antennas, respectively. The measured results are in good conformance with the simulated design. This antenna finds its potential usage in V2X and private 5G networks and can be extended for full-duplex MIMO implementations.

Slot fed circularly polarized magneto-electric dipole antenna array fed by optimized printed microstrip gap waveguide network

&lt;p&gt;A compact, circularly polarized 8 × 8 antenna array is designed for the 60 GHz band. The array comprises circularly polarized magneto-electric dipoles (CP-ME-Dipole) excited by narrow slots. The slots are fed by a printed gap waveguide (PGWG) cooperative network optimized based on the termination of the effective impedance of the array elements. Thus, it accounts for the space mutual coupling of the antenna elements. A procedure based on the full-wave analysis of a 4 ´ 4 array is used to estimate each element’s 8 × 8 array effective port impedance. The cooperative feeding network is designed based on the known effective impedances. The array is divided into two half subarrays out of phase from each other, and a rectangular waveguide feeds both sides. The commonly measured bandwidth of 18.3% achieves return loss better than 10 dB and an axial ratio below 3 dB (AR) of less than 3 dB. A maximum gain of 26.2 dBic with a high radiation efficiency of 82% radiation efficiency.&lt;/p&gt;