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The fifth generation (5G) mobile communication systems employ technologies such as massive MIMO, millimeter-wave (mmWave), and ultra-dense networks to support higher transmission data rate and lower latency, thereby enabling commercial deployment. Furthermore, the forthcoming sixth generation (6G) networks will integrate terrestrial and non-terrestrial networks, aiming to achieve full spectrum, full applications, and global coverage. Whether in the context of 5G or 6G networks, base transceiver stations (BTS) require a substantial number of radio frequency (RF) transceiver chains and antenna array, particularly in mmWave frequency bands. It is known that bandpass RF filters between antenna elements and transceivers are key components for suppressing out-of-band spurs and interference. The single board seamless integration of transceivers and antennas has become a growing trend. It means there is no extra room for a large number of filters at mmWave bands, leading to the emergence of integrated designs that combine filtering circuitry with antennas, known as filtenna or filtering antenna. With illustrated examples, the design methodologies, operational principles, and implementation strategies of filtennas are reviewed in this paper.

Objective: Improve the mechanization and automation of the pretreatment process of China's freshwater fish processing industry. Methods: The catfish head cutting simulation model is constructed by the numerical analysis software ANSYS/LS-DYNA, and the catfish head removal process is simulated and analyzed and the motion parameters are optimized by FEM. The blade speed and transportation speed are adjusted with the minimum cutting power consumption as the optimization goal, and the accuracy of the simulation results is verified by the prototype test. Results: When the speed of the blade is 850 r/min and the conveying speed is 14 cm/s, the cutting section of the fish head is smooth and smooth, the sensory of the section is good, and the cutting efficiency of the head can be guaranteed. Conclusion: The established simulation model of disc cutter cutting fish head can describe the motion process, but the accuracy needs to be improved.

Objective: In order to improve the mechanization and automation level of catfish head cutting. Methods: Through the study on the shape parameters and friction characteristics of catfish, the related parameters of catfish were obtained. Based on the machine vision technology to identify the assembly line fish, the end of the fish skull was defined as the fish head cutting track line, and an adaptive adjustment device was designed to adjust the position of the fish body, so that the disc cutter can avoid the skull for head removal. The GUI was designed in order to achieve visual control. Results: The system test results showed that the success rate of cutting track line discrimination of the image acquisition system reached 90%, with the average error of the adaptive adjustment system of 0.21 cm, which confirmed the reliability of the system. Conclusion: According to the preset processing efficiency, about 600 catfish can be processed per hour.

This article demonstrates a planar dual-band array antenna for millimeter-wave applications, which has a left-hand circular polarization and a right-hand circular polarization for two operating bands, respectively. By using aperture-fed stacked-curls, the proposed antenna can attain broad axial ratio (AR) bandwidths in both K- and Ka-bands through a single port. Meanwhile, two stacked-curls are designed to rotate in different directions for achieving orthogonal circular polarizations in two bands, respectively. An $8\times 8$ stacked-curls array antenna is designed and manufactured for verifications. The measured 3 dB AR bandwidths are 11.59% (18.7-21 GHz) in the K-band and 9.93% (26.8-29.6 GHz) in the Ka-band, with reflection coefficient lower than −10 dB. The maximum gain in K- and Ka-bands are 18.59 dB and 18.13 dB, respectively. The proposed antenna can be used for developing compact satellite communication systems.

To reveal the thermal-force coupling characteristics of the laser in-situ consolidation (ISC) of carbon fibre-reinforced poly-ether-ether-ketone (CF/PEEK) composites, a two-dimensional transient thermal-force model of CF/PEEK composites was constructed using COMSOL Multiphysics finite element simulation software to calculate the temperature history and the thermal stress variation of CF/PEEK composites during the laser-assisted automated tape placement (LATP) process. The results show that the temperature field formed on the surface of each layer by the laser spot during LATP is stable, and the temperature gradient at the front of the spot movement direction is higher than that at the back edge. The maximum stresses in the laminate occur on both sides of the first CF/PEEK layer and the stresses are unevenly distributed along the length and thickness directions of the lay-up. The composite material on both sides of the laminate tends to 'shrink' compared to its original position. [ABSTRACT FROM AUTHOR]

In this paper, we proposed an integrated hybrid antenna based on spoof surface plasmon polaritons (SSPPs) which combines with omnidirectional antenna (ODA) and the frequency beam scanning antenna (FBSA). The ODA is fed by the SSPPs and the operating principle of FBSA is based on the higher-order modes of the SSPPs. The radiation mechanisms of the proposed integrated antenna are that the low-pass transmission modes of SSPPs are used to excite the ODA and the higher-order modes of SSPPs are utilized to generate the frequency beam scanning waves. That is to say, the SSPP design not only serves as the feeding structure for the ODA, but also acts as the radiating element for the FBSA. Simulated results show that the proposed integrated antenna achieves two impedance bandwidths. Within the operating bandwidth 2.32 GHz to 4.42 GHz, the proposed integrated antenna achieves omnidirectional radiation patterns, which enables the simultaneous use for wireless local area network (WLAN) and 5 G applications. Meanwhile, from 11.45 GHz to 25.5 GHz, the proposed integrated antenna acts as a wide-angle frequency beam scanning characteristic and can be used for planar integrated communication systems. Additionally, a prototype of the proposed integrated hybrid antenna is fabricated and tested. The measured results have a good agreement with the simulated ones.

Ever since the deployment of the first-generation of mobile telecommunications, wireless communication technology has evolved at a dramatically fast pace over the past four decades. The upcoming fifth-generation (5G) holds a great promise in providing an ultra-fast data rate, a very low latency, and a significantly improved spectral efficiency by exploiting the millimeter-wave spectrum for the first time in mobile communication infrastructures. In the years beyond 2030, newly emerged data-hungry applications and the greatly expanded wireless network will call for the sixth-generation (6G) communication that represents a significant upgrade from the 5G network - covering almost the entire surface of the earth and the near outer space. In both the 5G and future 6G networks, millimeter-wave technologies will play an important role in accomplishing the envisioned network performance and communication tasks. In this paper, the relevant millimeter-wave enabling technologies are reviewed: they include the recent developments on the system architectures of active beamforming arrays, beamforming integrated circuits, antennas for base stations and user terminals, system measurement and calibration, and channel characterization. The requirements of each part for future 6G communications are also briefly discussed.

Inflammatory bowel disease (IBD) refers to long-term medical conditions that involve inflammation of the digestive tract, and the global incidence and prevalence of IBD are on the rise. Gut microbes play an important role in maintaining the intestinal health of the host, and the occurrence, development, and therapeutic effects of IBD are closely related to the structural and functional changes of gut microbes. Published studies have shown that the natural products from traditional Chinese medicine have direct or indirect regulatory impacts on the composition and metabolism of the gut microbes. In this review, we summarize the research progress of several groups of natural products, i.e., flavonoids, alkaloids, saponins, polysaccharides, polyphenols, and terpenoids, for the therapeutic activities in relieving IBD symptoms. The role of gut microbes and their intestinal metabolites in managing the IBD is presented, with focusing on the mechanism of action of those natural products. Traditional Chinese medicine alleviated IBD symptoms by regulating gut microbes, providing important theoretical and practical basis for the treatment of variable inflammatory intestinal diseases. [ABSTRACT FROM AUTHOR]

A compact dual-polarized antenna element covering the frequency bands of 0.773~1.0405 GHz and 1.69~2.83 GHz is proposed in this paper. The nested scheme is adopted and the performances of the lower- and upper-band element are analyzed, respectively. A ground platform in the center of lower-band element lowers the resonance frequency of element, makes the structure compact, and suppress the mutual interference between the lower- and upper-band elements. The simulated and measured results show that the proposed structure has stable smooth radiation patterns and the peak gains of 8.83 and 9.34 dBi for the lower- and upper-band elements, respectively. Based on the proposed elements, an array composed of three lower-band elements and five upper-band elements is designed and measured. The results show that the array achieves a stable flat half-power beamwidth (HPBW), isolation better than 25 dB and cross polarization levels less than -15 dB are obtained. The proposed antenna is a candidate for the multi mobile communication systems.

In order to accurately design microwave, millimeter-wave components and circuits, a simple and accurate method for extracting extremely wideband characteristics of the printed circuit board (PCB), including relative dielectric constant, dielectric loss tangent, and equivalent copper conductivity, is proposed and validated in this paper. By properly selecting wideband distribution of multiple TMmn0 modes in the designed circular substrate integrated waveguide (CSIW) cavities, extremely broadband properties of PCB can theoretically be extracted with only one pair of CSIW cavities. The proposed method overcomes the limitations of conventional methods that only support narrowband applications, require a large number of cavities, and have relatively large errors. The experiments show that the proposed method is able to extract, accurately and efficiently, 8-110 GHz characteristics of a TLY-5Z substrate-based PCB and the extracted results are verified by designing and measuring the fourth-order Chebyshev filter at X-band.

In this paper, a band-pass filter based on the spoof surface plasmon polaritons (SSPPs) and coplanar waveguide (CPW)-based coupling structure is proposed. The design concept of the proposed band-pass filter is to use the SSPP structure and CPW-based coupling structure for controlling the high cut-off frequency and filtering the low-frequency wave, respectively, which means that the low and high cut-off frequencies of the band-pass filter can be independently controlled. The physical mechanism of the proposed band-pass filter is explained with the aid of dispersion curves, electric field distributions, and equivalent circuits. Moreover, parametric studies are conducted to analyze the effects of the key parameters on the controllable performance of the band-pass filter, which is useful for practical designs. Furthermore, in order to improve the high-frequency performance, the split ring resonators are added to the structure. The simulation results show that the proposed band-pass filter achieves a bandwidth (for |S11| 21| > -1.6 dB) of 35.9% (7.31-10.51 GHz). The experimental results validate the proposed concept and measured results are in a good agreement with simulated ones, which indicate that the proposed bandpass filter is believed to be significantly promising for further developing plasmonic functional devices at microwave frequencies.

A low-profile wideband metasurface antenna with quad-polarization reconfiguration ability is presented in this paper. The proposed metasurface antenna is composed of a square patch, a metasurface formed by a lattice of 4 × 4 periodic metal plates, and four switchable feeding probes connected with two designed single-pole double-throws switches. By properly selecting the feeding probes, the polarization of the metasurface antenna can be dynamically reconfigured among four polarization states, i.e., x-direction linear polarization, y-direction linear polarization, left-hand circular polarization, and right-hand circular polarization. To validate the proposed concept, a prototype operating at 5.6 GHz with a relatively height of 0.067 λ0 (λ0 is the operating wavelength in free space) is designed, fabricated, and measured. The measured results show that both the 10-dB impedance bandwidths and the 3-dB axial ratio bandwidths are wider than 5.1-6.0 GHz for the linear and circular polarization states. The measured maximum gains are 9.39 dBic and 9.85 dBi for the circular polarization states and the linear polarization states, respectively. The simulation and experimentation verify that the proposed antenna can achieve quad-polarization reconfigurable features in a wide frequency band, which indicate the good performance of the proposed polarization reconfigurable metasurface antenna.

A dual-polarized antenna with omnidirectional radiation and high isolation performance is proposed in this paper. The proposed antenna consists of courtyard-shaped metal frame, feeding network, and metal background. Working mechanism of the proposed antenna is analyzed by the theory of characteristic modes. Two orthogonal polarizations can be achieved by utilizing the orthogonal current distributions on the courtyard-shaped metal frame. In order to obtain the horizontal-polarized mode, eight slots etched on the walls of the courtyard-shaped metal frame are excited. A feeding network is placed at the inner part of courtyard-shaped metal frame for a compact design. Measured results show that the proposed antenna can cover the impedance bandwidth of 1.80–2.81 GHz for both polarizations with their corresponding isolations better than 35 dB. A peak gain of 7 dBi and a gain ripple less than 3 dB in the horizontal radiation plane are achieved. The proposed antenna can be applied in the indoor wireless communication.

In this paper, we propose a 4 × 4 low-profile wideband patch array antenna with radiation pattern agility. The digital-controllable antenna element is composed of a square driven patch, a 2×2 parasitic patch array, and two switchable feeding ports, which are connected to a designed single-pole double-throw switch. Due to the symmetrical structure, individual excitation at the two feeding ports produces a 1800 phase difference, giving rise to two basic digital elements of “0”and “1,”respectively. By switching the feeding ports for all antenna elements using a micro-controller unit, the radiation beam of the 4×4 array antenna can be dynamically reconfigured. To validate the proposed concept, a prototype operating at 5.7 GHz with an overall size of 3.42λ0 × 3.42λ0 × 0.069λ0(λ0 is the free-space wavelength at 5.7 GHz) was fabricated and measured. The measured 10-dB return loss bandwidths for all the states cover the frequency band of 5.12-6.32 GHz. The simulated and measured results show close agreement, which proves the powerful dynamical beam manipulation capability of the proposed array antenna.

This paper presents a frequency and polarization reconfigurable patch antenna with a small gain variation. Eight discrete operating frequency bands can be achieved by properly switching shorting pins, and three polarization states, i.e., left-hand circularly polarization, right-hand circularly polarization, and linearly polarization, can be realized simultaneously by adjusting perturbation segments. A stable gain performance is obtained within a wide reconfigurable frequency range, as well as all the reconfigurable polarization states, by utilizing the loss-character of p-i-n diodes when shorting pins are properly switched ON/OFF for different states. A prototype is designed, fabricated, and measured. The simulated and measured results agree as well. The experimental results show that the proposed antenna exhibits a simple reconfigurable network, a wide switching frequency range, a good element gain, and a small gain variation less than 1.8 dB across all the operating states.

This paper presents a 3D absorptive frequency-selective reflection structure (AFSR) and absorptive frequency-selective transmission structure (AFST) with one reflection/transmission band and two absorption bands. The 3D AFSR utilizes the intrinsic reflection band and higher order absorption band of a wideband 3D absorber. By simply loading a printed gap capacitor in the structure, the reflection band can be easily tuned by varying the capacitance of the capacitor. A design example is presented, with a reflection band of 24.7% fractional bandwidth (FBW), a lower absorption band of 72.5% FBW, and a higher absorption band of 48.6% FBW. A 3D AFST composed of the 3D AFSR and a parallel-plate waveguide is then proposed. Its general operating principle is demonstrated, such that the 3D AFST can be seen as a combination of a 3D AFSR and a 3D band-pass FSS, which can independently contribute to the absorption and transmission, respectively. A set of guidelines is proposed to facilitate the design. A prototype of the proposed AFST is fabricated and measured. The measured results show that the transmission band is with a minimum insertion loss of 0.4 dB and an FBW of 30%. Moreover, the lower and higher absorption bands are with 63.9 % and 47.6 % FBW, respectively. The proposed AFST has a simpler structure, wider lower absorption bandwidth, and thinner thickness compared with previous structures.

A Ka-band waveguide continuous transverse stub antenna array with full-corporate-feed network is presented in this paper. Multiple-section stepped-impedance transformers are used for wideband impedance matching of the radiation slots. The required high-quality quasi-TEM wave excitation is generated by a wideband plane-wave generator (WPWG). Compared with the conventional pillbox structure, the WPWG produces a quasi-TEM wave with more uniform amplitude distribution. By using the combination of these design features, significant increases both in bandwidth and antenna aperture efficiency are achieved. For demonstration, a prototype is designed, fabricated, and measured. Excellent agreement is achieved between simulations and measurements. The antenna is matched over the entire Ka-band of 26-40 GHz. A high antenna aperture efficiency of over 75% and a low cross-polarization of less than -46 dB are achieved over the entire bandwidth. The demonstrated features of wideband, high aperture efficiency, and low cross-polarization have great potentials for millimeter-wave applications.

In this paper, a planar wideband antenna array with wide scanning angle in both E- and H-planes is proposed. The dipole antenna is used as an essential element of the array. To enlarge the scanning angle of the array, two layers of frequency selective surface (FSS) superstrates are loaded on the top of the antenna elements. A conducting-patch with shorting pins is loaded under the unit patch to enlarge the bandwidth of the array. Both simulated and measured results have confirmed that the proposed antenna array can scan up to 85◦ and 70◦ in the E- and H-planes from 8 GHz to 11 GHz, respectively. [ABSTRACT FROM AUTHOR]