Search

A compact low‐profile dual‐band dual‐polarized wearable patch antenna, capable of working in 2.4 and 5.8 GHz ISM band for either on‐body or off‐body applications with different radiation patterns in each working band, is presented in this paper. The fabricated antenna consists of four layers including modified ground and patch layers and two dielectric layers made of jean fabric, and it has a radius of 30 mm with overall height of 3.4 mm fed by a single probe. The proposed structure is designed in a way that is capable of radiating linearly polarized (LP) waves in lower working frequency and circularly polarized (CP) waves in its upper working band. The ground plane is modified to ensure the dual‐band radiation as well as miniaturization of the antenna. The patch of the antenna benefits from truncated corners and four circular stubs which are practically coupled with antenna's modified ground to provide desired axial ratio and dual polarization capability. With the help of computer‐based simulations, the antenna is placed on human body tissue and the calculated amount of SAR values in each band for 1 g tissue is 0.15 and 0.89 Wkg, respectively, which guarantee the safety of the human body in close proximity to the antenna. [ABSTRACT FROM AUTHOR]

Substituting thermodynamically favorable ethanol oxidation reaction (EOR) for oxygen evolution reaction (OER) engenders high‐efficiency hydrogen production and generates high value‐added products as well. However, the main obstacles have been the low activity and the absence of an explicit catalytic mechanism. Herein, a heterostructure composed of amorphous vanadium oxide and crystalline nickel nitride (VOx−Ni3N) is developed. The heterostructure immensely boosts the EOR process, achieving the current density of 50 mA cm−2 at the low potential of 1.38 V versus reversible hydrogen electrode (RHE), far surpassing the sluggish OER (1.65 V vs RHE). Electrochemical impedance spectroscopy indicates that the as‐fabricated heterostructure can promote the adsorption of OH− and the generation of the reactive species (O*). Theoretical calculations further outline the dual polarization of the Ni site at the interface, specifically the asymmetric charge redistribution (interfacial polarization) and in‐plane polarization. Consequently, the dual polarization modulates the d‐band center, which in turn regulates the adsorption/desorption strength of key reaction intermediates, thereby facilitating the entire EOR process. Moreover, a VOx−Ni3N‐based electrolyzer, coupling hydrogen evolution reaction (HER) and EOR, attains 50 mA cm−2 at a low cell voltage of ≈1.5 V. This work thus paves the way for creating dual polarization through interface engineering toward broad catalysis. [ABSTRACT FROM AUTHOR]

This paper introduces a novel high-speed Visible Light Communication (VLC) system capable of transmitting data rates of 120 Gbps. The system leverages the multiplexing capabilities of Dual Polarization (DP) and Orbital Angular Momentum (OAM) beams. It incorporates three Laser Diode (LD) sources operating at distinct wavelengths: red (700 nm), green (570 nm), and blue (450 nm). Each LD source generates four OAM beams operating at DP states, with each OAM beam carrying a data rate of 5 Gbps. The proposed system is designed for indoor VLC applications, considering line-of-sight (LoS) link configurations. The proposed system is evaluated for different detector surface areas, and transmission distance. The bit error rate (BER), and eye diagrams as evaluation metrics are used to characterize the performance of the system. The findings of different detection areas reveal that larger surfaces yield superior performance, with significant reductions in BER observed at the cost of collecting more ambient noise. Additionally, shorter transmission distances exhibit enhanced performance, underscoring the importance of propagation range in VLC systems. Through extensive performance analysis, our proposed DP-OAM-VLC model achieves an overall transmission capacity of 120 Gbps at a range of 1.1 m, with a BER below 10−3.

Abstract Substituting thermodynamically favorable ethanol oxidation reaction (EOR) for oxygen evolution reaction (OER) engenders high‐efficiency hydrogen production and generates high value‐added products as well. However, the main obstacles have been the low activity and the absence of an explicit catalytic mechanism. Herein, a heterostructure composed of amorphous vanadium oxide and crystalline nickel nitride (VOx−Ni3N) is developed. The heterostructure immensely boosts the EOR process, achieving the current density of 50 mA cm−2 at the low potential of 1.38 V versus reversible hydrogen electrode (RHE), far surpassing the sluggish OER (1.65 V vs RHE). Electrochemical impedance spectroscopy indicates that the as‐fabricated heterostructure can promote the adsorption of OH− and the generation of the reactive species (O*). Theoretical calculations further outline the dual polarization of the Ni site at the interface, specifically the asymmetric charge redistribution (interfacial polarization) and in‐plane polarization. Consequently, the dual polarization modulates the d‐band center, which in turn regulates the adsorption/desorption strength of key reaction intermediates, thereby facilitating the entire EOR process. Moreover, a VOx−Ni3N‐based electrolyzer, coupling hydrogen evolution reaction (HER) and EOR, attains 50 mA cm−2 at a low cell voltage of ≈1.5 V. This work thus paves the way for creating dual polarization through interface engineering toward broad catalysis.

Abstract The metasurface is a promising technology that can help next-generation wireless communication systems not only improve the signal-to-noise ratio (SNR), but also increase security and mitigate interference. Further, introducing dual polarization (DP) in a metasurface can enhance its capabilities with polarization diversity, polarization multiplexing, and polarization-switched modulation. In this paper, we study a DP-metasurface-assisted single-user wireless communication system and propose a novel scheme that can improve the spectral efficiency (SE) and bit-error-rate (BER) performance compared to those of conventional schemes by exploiting the orthogonal property of dual-polarized waves. We employ the DP metasurface to increase the SNR at the receiver and create a specific phase difference between the polarized signals by controlling the transmit precoder and the phases of the metasurface reflecting elements representing some modulated bits. At the receiver, we use the recovered phase information to realign the modulated symbols in both polarizations, which are then added coherently. The simulation results demonstrate that the proposed scheme achieves significantly higher SE and BER performance than those of some closely related works.

The metasurface is a promising technology that can help next-generation wireless communication systems not only improve the signal-to-noise ratio (SNR), but also increase security and mitigate interference. Further, introducing dual polarization (DP) in a metasurface can enhance its capabilities with polarization diversity, polarization multiplexing, and polarization-switched modulation. In this paper, we study a DP-metasurface-assisted single-user wireless communication system and propose a novel scheme that can improve the spectral efficiency (SE) and bit-error-rate (BER) performance compared to those of conventional schemes by exploiting the orthogonal property of dual-polarized waves. We employ the DP metasurface to increase the SNR at the receiver and create a specific phase difference between the polarized signals by controlling the transmit precoder and the phases of the metasurface reflecting elements representing some modulated bits. At the receiver, we use the recovered phase information to realign the modulated symbols in both polarizations, which are then added coherently. The simulation results demonstrate that the proposed scheme achieves significantly higher SE and BER performance than those of some closely related works. [ABSTRACT FROM AUTHOR]

Noise Equivalent Beta Naught is the different noise influence that beneficence to the radar signal. This type of noise is available in TerraSAR-X satellite images and expressed in forms of scaled polynomial described the noise power. On the other hand, Sigma naught or backscattering coefficient represents the average reflectivity of a horizontal material samples which used to reflect the nature of the land use and land cover in radar images. In this paper, radar satellite images in dual VV and HH polarization were used to study the influence of the noise on backscattering image classification. The result demonstrated that the visual interpretation of sigma naught which is result from the comparison between existence case and absence case (in the other word: with and without noise) of the noise illustrated that there is no different between them. In the other hand, for more details and more precise, an example of small images are used to show the values of obtained backscattering. The result demonstrated that the NEBN plays the main roles in decreasing the values of backscattering coefficient in TSX image. The influence of this noise had usually high in water body surface, because this surface is generally having small backscattering coefficients compared with land cover. [ABSTRACT FROM AUTHOR]

Noise Equivalent Beta Naught is the different noise influence that beneficence to the radar signal. This type of noise is available in TerraSAR-X satellite images and expressed in forms of scaled polynomial described the noise power. On the other hand, Sigma naught or backscattering coefficient represents the average reflectivity of a horizontal material samples which used to reflect the nature of the land use and land cover in radar images. In this paper, radar satellite images in dual VV and HH polarization were used to study the influence of the noise on backscattering image classification. The result demonstrated that the visual interpretation of sigma naught which is result from the comparison between existence case and absence case (in the other word: with and without noise) of the noise illustrated that there is no different between them. In the other hand, for more details and more precise, an example of small images are used to show the values of obtained backscattering. The result demonstrated that the NEBN plays the main roles in decreasing the values of backscattering coefficient in TSX image. The influence of this noise had usually high in water body surface, because this surface is generally having small backscattering coefficients compared with land cover.

【Objective】 The effects of Vertical-Vertical (VV) polarization, Vertical-Horizontal (VH) polarization, and dual polarization on microwave remote sensing retrieval of surface soil moisture (0-10 cm) were investigated. And analyze different data sources (Landsat-8, L8; Sentinel-2, S2) Effect of the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Water Index (NDWI) on the accuracy of remote sensing estimation of surface soil moisture. 【Method】 Based on the single polarization of VV and VH and the dual polarization model, NDVI and NDWI calculated by S2 and L8 were used to estimate vegetation water content (VWC), eliminate the influence of vegetation on backscattering, and obtain the soil backscattering coefficient. Then the water cloud model was used to invert the surface soil moisture in Daxing District of Beijing. 【Result】 For VV polarization, the estimation accuracy of VV+S2NDWI was best (R2=0.763, RMSE=1.55%). For VH polarization, the estimation accuracy of VH+S2NDVI was best (R2=0.622, RMSE=1.66%); The dual polarization (DP) + S2NDVI had a highest accuracy in retrieving surface soil moisture (R2=0.895, RMSE=0.89%); Compared with the NDWI, the NDVI has a better effect on removing the influence of vegetation, and the NDVI can be used to characterize the VWC. 【Conclusion】 NDVI is more suitable for removing the influence of vegetation in water cloud model, and the dual polarization method has higher accuracy in retrieving surface soil moisture.

This study presents dual polarization spectral analysis over updraft environments in thunderstorms. The composition and interaction of particle in updrafts environments are analyzed using the expansion that the spectral polarimetric provides in radar variables. Updrafts are identified using dual Doppler analysis and polarimetric signatures such as $Z_{\text{dr}}$ columns. Spectral techniques are presented to estimate the spectrum in updraft and mixed-phase environments. A separation in the spectrum of melting ice and rain was observed in the analyzed updrafts. This separation in the spectrum allows us to study the polarimetric characteristics and interaction of melting ice and rain. Furthermore, scattering simulations were carried out to validate the spectral signatures attributed to melting ice. It was found that small ice particles mixed with rain can produced similar polarimetric characteristics as the one observed in the spectral analysis. Conceptual models based on the spectral observations are presented to illustrate the interaction of ice particles with a recirculation and a vigorous updraft.

This paper proposes dual-band dual linearly-polarized (LP)/circularly-polarized (CP) antennas using combined metasurface and patch for ultra high frequency (UHF) and 2.45-GHz RF identification (RFID) readers. A metasurface and two stacked patches are employed for the lower and upper bands, respectively. The metasurface and patches are incorporated with a common feeding structure which is composed of two orthogonal microstrip lines and a crossed slot to produce the dual-wideband dual-LP radiation. To reduce the back radiation and improve the gain, the antenna is backed by a metallic cavity. Taking advantage of its low-profile structure, the dual-LP antenna is further integrated with a dual-band branch-line coupler to realize dual-CP radiation. Both proposed antennas yield stable radiation performances across dual operating bands which completely cover the assigned RFID spectrum at the UHF ( $860-960$ MHz) and 2.45-GHz ( $2400-2500$ MHz) bands.

Effective ship detection in synthetic aperture radar (SAR) imagery is crucial for maritime safety and surveillance. Despite the advancements in deep learning for SAR ship detection, significant challenges remain, particularly in large scenes. These challenges are twofold: the detection of extremely small ships is often hindered by inadequate feature extraction, and the presence of inshore ships is obscured by pronounced land-based interference, both of which lead to reduced detection accuracy. To address these issues, we present a novel deep learning framework that integrates constant false alarm rate (CFAR) processing with dual-polarization data, termed the CFAR-guided dual-polarization fusion framework (CFAR-DP-FW). The integration is designed to enhance the detection sensitivity for small-scale maritime targets by utilizing dual-polarization's rich feature representation, and CFAR's strength in suppressing background noise, highlighting potential targets. The proposed CFAR-DP-FW consists of three core components: the CFAR dual-polarization detector provides initial target indication; the CFAR field generator constructs a probabilistic ship presence map, reducing reliance on CFAR's hard thresholds; and the CFAR guidance dual-polarization network incorporates a novel feature extractor and enhancement module, tailored to amplify relevant features, and suppress noise. This strategic fusion within our framework markedly improves the detection of small and inshore ships. Evaluated on the large-scale SAR ship detection dataset-v1.0, our framework demonstrates superior performance, surpassing 20 state-of-the-art models. It achieves a 3.28% increase in mean average precision for inshore ships over the next best-performing model, validating its efficacy in tackling the intricate challenges of large-scale SAR ship detection.

In order to prevent and manage damage caused by localized torrential downpours, the quantitative observation of rainfall is crucial. Considering the spatial complexity and vertical variability of rainfall, it is important to obtain low-altitude, high-resolution radar observations to reduce uncertainty in radar rainfall estimates. In this paper, we present an electromagnetic wave rainfall gauge system (EWRG) that detects rainfall within the observation area and estimates the areal rainfall using electromagnetic waves. The EWRG system was developed based on a subminiature size antenna, a K-band dual-polarization transceiver, and advanced high-resolution, high-speed signal processing technology. The system design and signal processing techniques are described in detail. The EWRG has the advantage of overcoming the limitations of conventional cylindrical ground rain gauges, such as the contamination and spatial inaccuracy of rain gauges, which cause uncertainty in quantitative precipitation measurement. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The nonlinear frequency division multiplexing (NFDM) transmission scheme continues to attract high interests in optical communications due to its robustness against nonlinearity and dispersion. The use of Hermite Gaussian (HG) wave-carriers has been proposed and has been shown to out-perform conventional methods used by state-of-the-art single polarization NFDM systems due to their excellent time-bandwidth-product (TBP) efficiency. In this work, employing the Manakov model, we investigate and demonstrate, for the first time, a high-capacity dual polarization NFDM (DP-NFDM) transmission system based on HG wave-carriers, enhanced by a single parameter equalizer. We report here, a record high spectral efficiency of 12 bits/s/Hz for dual-polarization HG-based DP-NFDM systems.

Accurate measurement of angular positions on the sky requires a well-defined system of reference, something that in practice is realized by the International Celestial Reference Frame (ICRF) with observations of distant (typical redshift $\sim$1) Active Galactic Nuclei (AGN). At such great distances a subset of these objects exhibit as little as 10$-$50 $\mu$as/year observed parallax or proper motion, thus giving the frame excellent spatial and temporal stability. Until fairly recently the majority of AGN centered imaging was accomplished in the S (2.3 GHz) and X (8.4 GHz) radio frequency bands, however S-band observations for reasons such as sensitivity “plateauing”, increased source structure (jets), and radio frequency interference (RFI) have become less productive. Following spacecraft telemetry moves to higher frequencies and a desire to strengthen JPL's leadership in defining the next-generation of celestial reference frames has motivated the development of a “Quad-band” prototype receiver that operates in X, Ku, K, and Ka band in both right hand (RCP) and left hand (LCP) circular polarization. The goal of this receiver is to achieve less than a 20 % increase in noise over the Jansky Very Large Array (JVLA, NRAO) performance specification, which in such a wide bandwidth represents a revolutionary capability. To evaluate the various technical developments of the 8 GHz$-$40 GHz receiver the feedhorn optical beam was designed to interface to the US based Very Long Baseline Array (VLBA). The receiver's intermediate frequency (IF) spans 4 GHz$-$8 GHz, giving rise to up to eight 4 GHz IF channels for a fully populated instrument. This paper outlines the technical development of a 2$^{1}$/$_{2}$ octave wide (8 GHz$-$40 GHz) X-Ka band prototype receiver, fulfilling a need for super broadband technology within the VLBI network. An important additional benefit of the wideband receiver approach is its simplicity and low cost of operation.

This paper presents a low-profile wideband, dual-polarized patch antenna using differential-paired, multi-mode arms. By employing the arrow-shaped, differential-paired arms, three modes of them are excited simultaneously, leading to a broad bandwidth. The shorting pins are uniquely inserted at the wings of the arms to obtain stable radiation patterns. Then, two pairs of arms are structured like the dipoles and a dual-polarized antenna is designed. In addition, by employing coplanar coupling feeding structures, a good wideband impedance matching is also achieved without increasing the height. For demonstration, a wideband dual-polarized patch antenna is designed and measured. Benefitting from the advantages of the multi-mode patch and symmetrical structure as a dipole antenna, the proposed dual-polarized antenna operates between 2.10–3.95 GHz, possessing a 10-dB impedance bandwidth of 61%, a profile of 0.1λ0, an average gain of 7.31 dBi, and stable radiation patterns. [ABSTRACT FROM AUTHOR]

Because of its good beam coverage and beam scanning abilities, the Luneburg lens (LL) is a promising multibeam antenna for the fifth-generation (5G) wireless communications. However, the conventional LL has a spherical formfactor, exhibiting a large volume, large weight, and curvature surface, all of which limit the adoption of an LL in practice. To alleviate the problem, a flat LL is proposed, with transformation optics to convert the conventional spherical structure into a flat one. However, a high permittivity distribution is usually required in a transformed flat LL, causing of server reflections, which further degenerates the performance of the LL in terms of both gain and efficiency. In this article, a millimeter-wave dual-polarized flat Luneburg lens antenna (FLLA) is proposed following the transformation of optics, and implemented using multilayer PCBs, where a reflection cancellation method is introduced to optimize the multilayer structure to improve its gain and efficiency. The designed FLLA is exemplified in the Ka-band and fed using a dual-polarized patch antenna. The measured results show that the designed FLLA has an impedance bandwidth (|S11| ≤ −10 dB) of 27.5–32.6 GHz, a gain of 16.8–18.8 dBi over the operating band, and a beam scanning range up to ±25°/±24° with a gain loss of 1.72 dB/1.7 dB in either E- or H-plane, respectively. [ABSTRACT FROM AUTHOR]

In this article, a microwave (MW)/millimeter wave (MMW) aperture-sharing antenna is proposed. The antenna is constructed using two orthogonal columns of grounded vias from a 3.5 GHz slot-loaded half-mode substrate-integrated waveguide (HMSIW) antenna. These vias are reused to create two sets of 1 × 4 MMW substrate-integrated dielectric resonator antenna (SIDRA) arrays. With this proposed partial structure reuse strategy, the MW antenna and MMW arrays can be integrated in a shared-aperture manner, improving space utilization and enabling dual-polarized beam steering capability in the MMW band, which is highly desirable for multiple-input multipleoutput (MIMO) applications. The integrated antenna prototype was manufactured and measured for verification. The 3.5 GHz antenna has a relative bandwidth of 3.4% (3.44–3.56 GHz) with a peak antenna gain of 5.34 dBi, and the 28 GHz antenna arrays cover the frequency range of 26.5–29.8 GHz (11.8%) and attain a measured peak antenna gain of 11.0 dBi. Specifically, the 28 GHz antenna arrays can realize dual-polarization and ±45° beam steering capability. The dual-band antenna has a very compact structure, and it is applicable for 5G mobile communication terminals. [ABSTRACT FROM AUTHOR]

The use of SAR data for flood mapping is well established. However, the problem of the missed detection of rapidly evolving floods remains. Recently, the Italian Space Agency deployed the COSMO-SkyMed Second Generation (CSG) constellation, with an on-demand capability that makes it possible to reduce the number of missed floods. However, for on-demand SAR acquisitions, pre-flood images are generally not available, and change-detection methods, commonly adopted for flood mapping using SAR, cannot be applied. This study focused on the high-resolution CSG images of a flood that occurred in central Italy. An accurate analysis of the radar responses of the different targets included in the scenes observed by GSG was performed. Then, a methodology to detect floods using high-resolution single SAR images was developed. The methodology was based on image segmentation and fuzzy logic. Image segmentation allowed us to analyze homogeneous areas in the CSG images. Fuzzy logic was used to integrate the SAR data with ancillary information that was useful when change-detection methods could not be applied. A comparison with the maps produced by the Copernicus Emergency Service, using high-resolution optical images, demonstrated the reliability of the methodology. [ABSTRACT FROM AUTHOR]

This paper presents a novel design for and an experimental study of a dual-polarized quad-port MIMO antenna. The design achieves resonance at five distinct frequency bands with reduced mutual coupling. The design includes a single annular ring slot, four truncated rectangular corners, and a truncated aperture to improve resonance behavior. The design is then extended to a four-port MIMO antenna by including a ground-plane slit to enhance isolation between antenna elements at the center resonance band. The antenna achieves resonances at 5 distinct bands, ranging from 1.5 to 8.4 GHz, with significant mutual coupling reductions. The resonances of the quad-port pentaband MIMO antenna are achieved at 1.55 GHz (1.5–1.65 GHz), 2.5 GHz (2.4–2.7 GHz), 5.2 GHz (5–5.85), 7.3 GHz (7.1–7.4), and 8.15 GHz (7.9–8.4), with respective mutual coupling reductions of 27 dB, 37 dB, 21 dB, 29 dB, and 21 dB. Additionally, the 3 dB axial ratio bandwidth (ARBW) is observed at 6.5% (1.5–1.6 GHz) and 15% (2.4–2.7 GHz) in 2 distinct bands, and the envelope correlation coefficient and diversity gain are calculated within the specified band range. Experimental measurements of the prototype for the quad-port antenna are conducted, with excellent agreement found between the results and the simulations. [ABSTRACT FROM AUTHOR]

As a key component of rainfall estimation, the understanding of raindrop size distribution (DSD) is a long-standing goal in meteorology and hydrology. Given that weather radar can observe the precipitation microphysics over large spatial and temporal scales, it has been broadly applied in DSD estimation. Traditional polynomial regression algorithms that correlate DSD parameters and radar signatures are still widely applied due to their simple structure and acceptable accuracy. This study proposes a new DSD retrieval model using dual-polarization radar observations based on long short-term memory (LSTM) network techniques. Three schemes able to retrieve the parameters of a normalized gamma DSD (LSTM- D 0 , LSTM- N w , and LSTM- μ) are proposed with different combinations of polarimetric radar measurement inputs. All LSTM estimators exhibit better performance than the polynomial regression method. The Nash-Sutcliffe efficiency coefficient for estimates of drop median diameter (D 0) and intercept parameter (N w) increases from 0.93 and 0.70 to 0.95 and 0.93 respectively at Chilbolton station. Poor estimates of the shape parameter (μ) using the polynomial regression estimator complicate real applications, whereas the remarkable improvement of LSTM model estimation facilitates practical applications. The temporal and spatial predictability is then estimated to investigate long-term estimator performance for various radars, or at least for all radar pixels of a single radar. The predictability, measured by the Nash coefficient, increases temporally by 0.08, 0.31, and 0.39 and spatially by 0.03, 0.19, and 0.23 for the parameters D 0 , log 10 N w , and μ respectively. This study contributes to improving quantitative precipitation estimates from radar polarimetry, enabling a better understanding of precipitation microphysics. • A new DSD retrieval model using dual-polarization radar observations based on LSTM network techniques was proposed. • The UK-wide study on 14 disdrometers revealed LSTM as an effective approach to enhance DSD parameter retrieval accuracy. • The temporal and spatial predictability for DSD parameters using LSTM are all better than that of the traditional methods. [ABSTRACT FROM AUTHOR]

In order to prevent and manage damage caused by localized torrential downpours, the quantitative observation of rainfall is crucial. Considering the spatial complexity and vertical variability of rainfall, it is important to obtain low-altitude, high-resolution radar observations to reduce uncertainty in radar rainfall estimates. In this paper, we present an electromagnetic wave rainfall gauge system (EWRG) that detects rainfall within the observation area and estimates the areal rainfall using electromagnetic waves. The EWRG system was developed based on a subminiature size antenna, a K-band dual-polarization transceiver, and advanced high-resolution, high-speed signal processing technology. The system design and signal processing techniques are described in detail. The EWRG has the advantage of overcoming the limitations of conventional cylindrical ground rain gauges, such as the contamination and spatial inaccuracy of rain gauges, which cause uncertainty in quantitative precipitation measurement.

Wireless communication is a fundamental requirement because of its low cost, high flexibility and convenience, continuing improvements in speed and connectivity, and accessibility in remote areas. One example is very small aperture terminal (VSAT) communication. A VSAT is a two-way satellite ground station operating at C-band and Ku-band frequencies, with linear and circular polarization in the C band and linear polarization in the Ku band. For the data transmitted by a satellite to be utilized by a user, the antenna on the user side must have dual-wideband and dual-polarization characteristics. In this study, a dual-polarization planar dual-wideband antenna with dimensions of 30 x 39 x 1.52 mm3 was designed using a dual-port approach. The introduction of a slot and perturbation on the patch side results in the dual-wideband characteristics of the antenna. The introduction of slots into the antenna ground results in circular polarization. The proposed antenna has resonant frequencies of 3 - 15 GHz on port 1 and 3.31 – 7.79 GHz and 9.05 – 15 GHz on port 2, with circular polarization characteristics on port 1 and linear polarization characteristics on port 2. On port 1, the gains at frequencies of 4.2 GHz is 3.93 dB, while on port 2, the gains at frequencies of 3.9 GHz is 0.51 dB.

Dual polarized printed multiple input multiple output (MIMO) antenna for Band 42 (3.4 - 3.6 GHz) with wave propagation models is presented. Polarization and spatial diversity are achieved by utilizing two printed bow-tie antennas in orthogonal orientation. The designed dual polarized antenna element with $2\times 2$ , $4\times 4$ and $8\times 8$ massive MIMO antenna configuration radiation patterns are deployed in selected geographical situation for detailed radio network planning using FEKO-WinProp platform. Knife edge diffraction, extended walfisch-ikegami and dominant path wave propagation models are implemented with designed MIMO antenna configurations. Modulation schemes of QPSK and QAM with corresponding data rates and throughput for all propagation models are presented. The signal strength and quality reflecting parameters reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), and signal to noise plus interference ratio (SNIR) are also evaluated for each model. From the simulation results dominant path model provides data rate and throughput of 3.827, 995 MBit/s and 3.577, 930.1 MBit/s for single stream of data in uplink and downlink respectively. The maximum data rate of 1.37 GBits/s is achieved for deployed base stations with $8\times 8$ massive MIMO antenna configuration effectively covering the entire geographical site.

Early-season crop mapping provides decision-makers with timely information on crop types and conditions that are crucial for agricultural management. Current satellite-based mapping solutions mainly rely on optical imagery, albeit limited by weather conditions. Very few exploit long-time series of polarized synthetic aperture radar (SAR) imagery. To address this gap, we assessed the performance of COSMO-SkyMed X-band dual-polarized (HH, VV) data in a test area in Ponte a Elsa (central Italy) in January–September 2020 and 2021. A deep learning convolutional neural network (CNN) classifier arranged with two different architectures (1-D and 3-D) was trained and used to recognize ten classes. Validation was undertaken with in situ measurements from regular field campaigns carried out during satellite overpasses over more than 100 plots each year. The 3-D classifier structure and the combination of HH+VV backscatter provide the best classification accuracy, especially during the first months of each year, i.e., 80% already in April 2020 and in May 2021. Overall accuracy above 90% is always marked from June using the 3-D classifier with HH, VV, and HH+VV backscatter. These experiments showcase the value of the developed SAR-based early-season crop mapping approach. The influence of vegetation phenology, structure, density, biomass, and turgor on the CNN classifier using X-band data requires further investigations, along with the relatively low producer accuracy marked by vineyard and uncultivated fields.

This paper presents a pattern reconfigurable dual-polarized dipole antenna with staggered parasitic elements operating in 3.5 GHz band. The proposed antenna is designed by assembling two linearly polarized antennas to be orthogonally polarized, and each antenna includes two parasitic elements and a single dipole element. A circuit including a varactor is inserted into each parasitic element, and the current phase of the parasitic element changes according to the capacitance of the varactor. Each antenna has a beam steering range of about ±30° in the E-plane, and the beamwidth and gain are maintained uniformly regardless of the steering angle due to the angled parasitic element. Also, because of the continuously changing characteristic of the varactor, the beam of the proposed antenna is steered continuously, and only four varactors are used. The size of the fabricated dual-polarized antenna is $1.40\lambda _{0}\times 1.40\lambda _{0}\times 0.47\lambda _{0}$ , and the measured results confirm that the antenna has an average gain of around 6 dB with 0.3 dB gain variation.

In this paper, a dual-polarized filtering Fabry-Perot antenna (FPA) with high-isolation is proposed. It consists of a feed element of differential-fed dual-polarized square patch and a partially reflecting surface (PRS). The patch is capacitively coupled with T-shaped resonators and shorting-vias to obtain broadband characteristic and radiation nulls. The PRS structure is composed of two complementary metasurface layers, which are selected for achieving a positive reflection phase gradient within the broad frequency range. More interestingly, thanks to the frequency selectivity feature, the PRS significantly enhances the filtering characteristic of the FPA. For verification, a prototype of the proposed antenna operating at the 5.5-GHz center frequency has been fabricated and measured. The prototype with an overall size of $\sim 2.0\lambda _{\text {min}} \times 2.0\lambda _{\text {min}} \times 0.49\lambda _{\text {min}}$ ( $\lambda _{\text {min}}$ is the free-space wavelength referring to the lowest operational frequency) result in an impedance bandwidth of 17.1% ( $5.02-5.96$ GHz) for 10-dB return loss and a high isolation of $\ge45$ dB. Moreover, the far-field measurements result in a good dual-polarized radiation with the peak gain of 13.0 dBi, cross-polarization level of $\le $ –25 dB within the passband, and out-of-band suppression level of $\ge20$ dB.

A wide-coverage unmanned aerial vehicle (UAV) antenna system for air-to-ground communications is proposed in this paper. The proposed antenna system has reconfigurable beam patterns based on five sets of dual-polarization and high gain antennas. Each antenna set is configured by a dual-polarization crossed inverted-V radiator and switched feed network to drive switched beamforming operations. Depending on the switch modes of the proposed antenna, main beam direction and circular polarization types can be independently selected. Further, each antenna set is faced toward the ground level at different angles from the center of UAV to provide wide beam coverage. To verify the antenna performance, each antenna set is designed at the center frequency of 5.7 GHz and total five sets are integrated with a switched feed network and a microcontroller. To implement the wide angle switched beamforming with 2-D angle-shifted main beams, a 3-D printed conformal fixture is used to connect both the antenna module and a drone body. The maximum measured bandwidth was more than 22% and the measured peak gain with the de-embedded switch feed network loss was about 10.2 dBic.

Very high wind loads represent one of the major problems for ultralarge-scale 5G base station arrays in the sub-6 GHz band, where dozens or even hundreds of antennas are used. An ultracompact dual-polarized cross-dipole antenna with an extremely small overall projected area is presented. The projected area is reduced by employing miniaturized cross dipoles and replacing the traditional ground plane with a defected ground structure (DGS) and metal mesh reflector. The DGS is utilized for size reduction and isolation enhancement. Therefore, an array with a low wind load is formed using antennas with an extremely small projected area, and each antenna in the array can be independently packaged using a streamlined radome that is conducive to airflow. The antenna prototype is designed, fabricated, and measured for the sub-1 GHz band. The results show that the impedance bandwidth is 680–970 MHz, the polarization isolation is higher than 20 dB, and the gain is approximately 6.5 dBi. Furthermore, the results verify that the proposed ultracompact antenna with excellent radiation performance is highly suitable for an ultralarge-scale 5G base station array with a low wind load. [ABSTRACT FROM AUTHOR]

This paper describes the implementation of an antenna-in-package (AiP) with a dual polarization function, supporting a three-dimensional (3D) beamforming operation. In order to implement 3D beamforming, a Yagi-type end-fire antenna supporting each of the x and y directions and a patch-type broadsided antenna supporting the z-direction were implemented. The broadside antennas have dual polarization functions so that they can be received in any direction. Each antenna was implemented in four array structures to support beamforming operations. The broadside antenna was designed in a 2 × 2 array structure, with a patch-type antenna and two linear dual polarization functions. The single antenna operated with a gain of 6 dBi, an E-plane beam width of ±45 degrees, and an H-plane beam width of ±50 degrees and had an antenna gain of 9~11 dBi as well as a vertical/horizontal forming operation with a radiation angle of ±22 degrees The end-fire antenna unit was designed in a 1 × 4 array structure with a Yagi-type antenna. The single antenna had a gain of 4 dBi, with an antenna gain of 8 dBi in the array structure, and it was improved to 11 dBi by adding a parasitic array director. The final end-fire antenna unit had a radiation angle of ±11 degrees and a beamforming coverage of ±45 degrees The vertical and horizontal design results were secured for reception in any direction, and all the array antennas had a return loss of 10 dB or less in the entire frequency band, from 57 to 66 GHz. [ABSTRACT FROM AUTHOR]

Substituting thermodynamically favorable ethanol oxidation reaction (EOR) for oxygen evolution reaction (OER) engenders high-efficiency hydrogen production and generates high value-added products as well. However, the main obstacles have been the low activity and the absence of an explicit catalytic mechanism. Herein, a heterostructure composed of amorphous vanadium oxide and crystalline nickel nitride (VO x -Ni 3 N) is developed. The heterostructure immensely boosts the EOR process, achieving the current density of 50 mA cm -2 at the low potential of 1.38 V versus reversible hydrogen electrode (RHE), far surpassing the sluggish OER (1.65 V vs RHE). Electrochemical impedance spectroscopy indicates that the as-fabricated heterostructure can promote the adsorption of OH - and the generation of the reactive species (O * ). Theoretical calculations further outline the dual polarization of the Ni site at the interface, specifically the asymmetric charge redistribution (interfacial polarization) and in-plane polarization. Consequently, the dual polarization modulates the d-band center, which in turn regulates the adsorption/desorption strength of key reaction intermediates, thereby facilitating the entire EOR process. Moreover, a VO x -Ni 3 N-based electrolyzer, coupling hydrogen evolution reaction (HER) and EOR, attains 50 mA cm -2 at a low cell voltage of ≈1.5 V. This work thus paves the way for creating dual polarization through interface engineering toward broad catalysis., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

In this article, a dual-polarized multibeam antenna is proposed. Two orthogonally polarized slotted waveguide antennas (SWAs) are cross-placed as the main radiator, which is designed based on ridged waveguides (RGWs) to reduce the width of the waveguides and obtain a wider steering range. The two SWAs are fed by two pillbox reflector beamforming networks (BFNs), and a special impedance transition is designed to reduce the reflection between the quasi-TEM wave in the parallel-plate waveguide (PPW) to the TE10 wave. By exciting different feeding patches in the focal planes of the pillbox reflectors, the SWA achieves different beams. In order to further increase the crossover level, the single-port excitation (SPE) and the dual-port excitation (DPE) method are used together to increase the equivalent source number in the compact area of the focal plane. Besides, the DPE method can also reduce the sidelobe level (SLL) of the beams excited by the side ports. A prototype is designed at the operating frequency of 10 GHz and fabricated by the 3-D-printed technology and computer numerical control (CNC) technology. The measured results show that the proposed antenna achieves ± 36° beam scanning in the multibeam plane with the minimum crossover level of −2.1 dB. The cross polarizations are below −20.0 and −15.9 dB for the horizontal polarization (H-P) and the vertical polarization (V-P), respectively. The advantages of dual polarization, high aperture efficiency, low cross polarization, wide beam scanning range, and low crossover level make this antenna a very appropriate choice in multibeam radars and communication systems. [ABSTRACT FROM AUTHOR]

This communication presents a dual-polarized transmitarray antenna with wide bandwidth and independent beam control for each polarization. A new low-insertion-loss transmitarray element allowing wideband dual-polarized operation is proposed by using magnetoelectric (ME) dipole with shared radiating structure and interleaved orthogonal feeding probes; 1 bit phase adjustment can be realized individually for each polarization with additional freedom in manipulating the cross-polarization over a fractional bandwidth of 23%. Three transmitarrays that achieve possibly different collimated beams and/or cross-polarization manipulation are designed and carried out at millimeter-wave frequencies covering from 23.5 to 32.5 GHz. Measurement results of the prototypes agree reasonably well with simulations, which validates the wideband operation and independent beam controls. [ABSTRACT FROM AUTHOR]

This article proposes a low-profile, dual-polarized $4\times 4$ antenna array for the fifth-generation (5G) applications. It originates from our previous linear-polarized design, but with two split dipoles. For each polarization, the current on the split dipoles will cancel each other out in one direction. In contrast, in the orthogonal direction, the current can be regarded as a driven dipole to couple energy to four parasitic patches. The proposed element has a profile of only $0.073\lambda _{0}$ (where $_{\mathrm {}}\lambda _{0}$ is one free-space wavelength at 27.85 GHz) with simulated standing wave ratio (SWR) < 2 from 22.11 to 33.6 GHz (BW ≈ 41.25%). The average gain is 8 dBi, and the peak gain reaches 10 dBi at approximately 31.5 GHz. Besides, the two polarizations possess almost the same performance due to the symmetry of the antenna. A 4 $\times 4$ antenna array is designed, simulated, and experimentally demonstrated based on a subarray that can support two orthogonally mode excitations. The measured results present an overlapped bandwidth of 28.4% and more than 25 dB isolation. In addition, the maximum gains are up to 19 and 18.9 dBi for Ports 1 and 2 excitations, respectively. Our proposed design has great application potential in vehicle-mounted millimeter-wave radar and 5G communications systems. [ABSTRACT FROM AUTHOR]

In this communication, a dual polarized (DP) stacked patch filtenna (filtering antenna) with a wide stopband is developed for tile array applications. The bandpass filtering property is realized by improving the feeding network and patch without adding extra bandpass circuit or size. An elaborate feeding structure with complementary pair of a short-circuited stub and an open-circuited stub (CSSOS) is developed, which generates two transmission nulls effectively enhancing the selectivity and suppressing the harmonic. Moreover, CSSOS has a small size and broadens the impedance bandwidth apparently by introducing an in-band resonance. By properly etching four U-shaped slots on the driven patch, a radiation null in the upper stopband is also generated. The nulls generated by the two approaches can be adjusted independently in wide ranges. For further harmonic suppression, bandstop striplines (BSSs) with ultralow insertion loss are developed. Measured results show that the filtenna performs a wide operating band (3.10–3.95 GHz) and a wide stopband up to 8 GHz with a rejection level higher than 16 dB. Besides, a 32-element tile phased array employing the filtennas is also fabricated and measured. A compact configuration, high selectivity, and good beam steering capacity are exhibited. [ABSTRACT FROM AUTHOR]

• A dual-band nonreciprocal radiation device under is investigated, which includes magneto-optical layer and silicon-based square-hole arrays. • Under TE polarization, the nonreciprocity at wavelengths of 15.945 μm and 16.475 μm reaches 0.91 and 0.82, respectively. • Under TM polarization, the nonreciprocity at wavelengths of 13.956 μm and 14.352 μm realizes 0.88 and 0.95, respectively. • At an external magnetic field of 3 T, the nonreciprocal device can achieve dual-band nonreciprocal radiation for TE and TM polarizations. Nonreciprocal thermal radiation has many applications in energy harvesting, military camouflage, and other fields. However, in the past, most nonreciprocal devices operated under single polarization, which undoubtedly limited the development of the nonreciprocal thermal radiation. In addition, previous research has focused on single-band nonreciprocal radiation. However, there is little study on dual-band nonreciprocal thermal radiation. We investigate a dual-band nonreciprocal radiation device under dual-polarization, which is composed of a metal layer, magneto-optical layer, and silicon-based square-hole arrays in two-dimensional form. The device can achieve dual-band nonreciprocal radiation at wavelengths of 15.945 μm and 16.475 μm under TE polarization. Under TM polarization, dual-band nonreciprocal radiation can be achieved at wavelengths of 13.956 μm and 14.352 μm. And the electromagnetic field distribution can explain potential physical mechanisms. It indicates that nonreciprocal radiation can be maintained well within a certain range of structural parameters. This work can provide new directions for the study of frequency selective detectors. [ABSTRACT FROM AUTHOR]

Because of its good beam coverage and beam scanning abilities, the Luneburg lens (LL) is a promising multibeam antenna for the fifth-generation (5G) wireless communications. However, the conventional LL has a spherical formfactor, exhibiting a large volume, large weight, and curvature surface, all of which limit the adoption of an LL in practice. To alleviate the problem, a flat LL is proposed, with transformation optics to convert the conventional spherical structure into a flat one. However, a high permittivity distribution is usually required in a transformed flat LL, causing of server reflections, which further degenerates the performance of the LL in terms of both gain and efficiency. In this article, a millimeter-wave dual-polarized flat Luneburg lens antenna (FLLA) is proposed following the transformation of optics, and implemented using multilayer PCBs, where a reflection cancellation method is introduced to optimize the multilayer structure to improve its gain and efficiency. The designed FLLA is exemplified in the Ka-band and fed using a dual-polarized patch antenna. The measured results show that the designed FLLA has an impedance bandwidth (|S11| ≤ −10 dB) of 27.5–32.6 GHz, a gain of 16.8–18.8 dBi over the operating band, and a beam scanning range up to ±25°/±24° with a gain loss of 1.72 dB/1.7 dB in either E- or H-plane, respectively.

In this article, a microwave (MW)/millimeter wave (MMW) aperture-sharing antenna is proposed. The antenna is constructed using two orthogonal columns of grounded vias from a 3.5 GHz slot-loaded half-mode substrate-integrated waveguide (HMSIW) antenna. These vias are reused to create two sets of 1 × 4 MMW substrate-integrated dielectric resonator antenna (SIDRA) arrays. With this proposed partial structure reuse strategy, the MW antenna and MMW arrays can be integrated in a shared-aperture manner, improving space utilization and enabling dual-polarized beam steering capability in the MMW band, which is highly desirable for multiple-input multipleoutput (MIMO) applications. The integrated antenna prototype was manufactured and measured for verification. The 3.5 GHz antenna has a relative bandwidth of 3.4% (3.44–3.56 GHz) with a peak antenna gain of 5.34 dBi, and the 28 GHz antenna arrays cover the frequency range of 26.5–29.8 GHz (11.8%) and attain a measured peak antenna gain of 11.0 dBi. Specifically, the 28 GHz antenna arrays can realize dual-polarization and ±45° beam steering capability. The dual-band antenna has a very compact structure, and it is applicable for 5G mobile communication terminals.

This paper presents a novel design for and an experimental study of a dual-polarized quad-port MIMO antenna. The design achieves resonance at five distinct frequency bands with reduced mutual coupling. The design includes a single annular ring slot, four truncated rectangular corners, and a truncated aperture to improve resonance behavior. The design is then extended to a four-port MIMO antenna by including a ground-plane slit to enhance isolation between antenna elements at the center resonance band. The antenna achieves resonances at 5 distinct bands, ranging from 1.5 to 8.4 GHz, with significant mutual coupling reductions. The resonances of the quad-port pentaband MIMO antenna are achieved at 1.55 GHz (1.5–1.65 GHz), 2.5 GHz (2.4–2.7 GHz), 5.2 GHz (5–5.85), 7.3 GHz (7.1–7.4), and 8.15 GHz (7.9–8.4), with respective mutual coupling reductions of 27 dB, 37 dB, 21 dB, 29 dB, and 21 dB. Additionally, the 3 dB axial ratio bandwidth (ARBW) is observed at 6.5% (1.5–1.6 GHz) and 15% (2.4–2.7 GHz) in 2 distinct bands, and the envelope correlation coefficient and diversity gain are calculated within the specified band range. Experimental measurements of the prototype for the quad-port antenna are conducted, with excellent agreement found between the results and the simulations.

This article presents a reconfigurable multifunctional metasurface (RMM) with independent control of orthogonally polarized waves. Each meta-atom of RMM has four varactor diodes (two sets of orthogonal parallel diodes) connected and voltage biased. The voltage difference of the two sets of parallel varactor diodes is a constant. Thus, the orthogonally polarized reflected wave can be tuned independently. Unlike in other reported voltage-controlled RMMs, in the developed RMM, biasing voltages can be applied in one direction only. A tunable range from 7.2 to 7.8 GHz can be achieved. Two functionalities of the proposed RMM, namely, beam steering and polarization conversion, are demonstrated numerically and experimentally. Beam steering can be independently achieved in the ${x}-/y$ -directions when the incident plane wave is an $x-/y$ -polarized plane wave. For an arbitrary linear polarized incident plane wave, the decomposed orthogonally polarized waves can also be reflected toward two predefined directions based on the dual-polarized independent tunability of the proposed design. As for polarization conversion, the reflected waves can be flexibly switched among linear-to-orthogonal (LP-to-XP), linear-to-circular, and linear-to-elliptical polarizations in the operating frequencies depending on the phase requirement. The polarization conversion ratio is up to 90% for LP-to-XP polarization and the axial ratio is smaller than 3 dB for linear-to-circular polarizations. [ABSTRACT FROM AUTHOR]

A planar antenna array exhibiting polarization-switchable endfire and ±broadside radiation without the employment of lumped components is proposed. The antenna is denoted as symmetrically stacked planar antenna (SSPA), which utilizes the phase difference between the top and bottom patches to enable dual-linear/circular polarized hemispheric radiation. This communication focuses on the dual-linear polarized aspect. One polarization is achieved when a 180° phase difference exists between the first-set of ports, while the perpendicular polarization is accomplished when the second-set of ports are in-phase. A four-element array is constructed to exemplify this concept at 28 GHz, and the main beam is steered across the sphere. A comparison with other designs reported in the literature is conducted to highlight the salient points of the proposed methodology regarding planar, dual-polarized, and lumped-components-free features. To validate the predicted and simulated results, a prototype of the four-element array is fabricated and measured. The measured results show that the proposed array can steer the beam from 0° to 55° in all directions for both linear polarizations. [ABSTRACT FROM AUTHOR]

A novel decoupling method by utilizing one $1\times2$ subarray to provide a pair of phase-reversed coupling paths for coupling energy cancellation is proposed. The newly proposed decoupling approach is implemented by symmetrically loading several U-type, I-type, and cross strips around the antennas to change the original couplings, so that two elements in the $1\times2$ subarray can form a pair of phase-reversed coupling paths into adjacent element in different subarray for coupling cancellation. Then, the couplings from the subarray to adjacent element are effectively suppressed, thus the isolations between different subarrays of the array are promoted. Moreover, the method can be also applied in improving the isolation between different polarizations in the same subarray. In addition, these strips not only have little influence on radiation characteristics of the antenna array, but also can be etched on the antenna layer without extra profile and process. For demonstration, one dual- polarized patch antenna array based on the new decoupling mechanism is designed. The results indicate that all the isolations between the subarrays of the proposed dual-polarized antenna array can achieve a very high level of over 25 dB in an operation band of 3.4–3.6 GHz. Compared with other decoupling methods, the proposed method can simultaneously improve complex multiple-port isolations among different subarrays and different polarizations to realize a very high isolation with less impact on antenna radiation. Due to above features, the proposed decoupling mechanism is expected to find potential applications in 5G dual-polarized multiple-input–multiple-output (MIMO) antenna array. [ABSTRACT FROM AUTHOR]

A novel hybrid metamaterial-transmission line (TL)-based dual-polarized omnidirectional antenna with a low profile and high port isolation for 5G indoor applications is proposed. A compact shared aperture hybrid metamaterial-TL structure is first proposed, which is carefully analyzed by dispersion curves and current distribution. The hybrid metamaterial-TL structure consists of a mushroom-like composite right/left-handed TL (CRLH-TL) and a ring-shaped mu-negative TL (MNG-TL), forming a pair of orthogonal zeroth-order resonant (ZOR) modes. The shunt ZOR mode of the CRLH-TL structure is successfully excited, which radiates vertically polarized (VP) waves. Horizontal polarization (HP) is realized by exciting a series ZOR response from the ring-shared MNG-TL. By simultaneously exciting two orthogonal ZOR modes, a dual-polarized (VP and HP) omnidirectional antenna with high isolation and good roundness is designed and fabricated. With a low profile of $0.06\lambda _{0}$ , this dual-polarized antenna shows a measured overlapped −10 dB bandwidth of 14.1% (3.3–3.8 GHz), a port isolation larger than 39 dB, radiation efficiency higher than 80%, and cross pol. levels lower than −18 dB. It demonstrates the advantages of low profile, compact size, high isolation, good bandwidth, and radiation performance, and simple design for 5G indoor microcell, router, multi-input–multi-output (MIMO), or in-band full duplexing applications. [ABSTRACT FROM AUTHOR]

In this communication, a dual-polarized filtering magneto-electric dipole (FMED) antenna and arrays are proposed for 5G n258 (24.25–27.5 GHz) operations. The FMED antenna was devised to incorporate filtering mechanisms using a built-in substrate integrated waveguide (SIW)-based filter plus slot-and-notch etching on the dipole element. As such, lower and upper radiation cutoffs and nulls were produced and tuned, independently. To overcome the problem of “high selectivity” of a filtering antenna that has not been correctly quantified and thus has no comparison, a new skirt measure metric named as radiation suppression index is initiated here. Design steps of the FMED element and novel feeding techniques are elaborated, where the SIW-based series-parallel slot-coupled feeders and the slot-coupled differential power divider were conceived for large-size array, to combat with the insertion losses. A prototype of 4 $\times $ 4 FMED array was implemented and tested for experimental verification. A high gain of 16.8 dBi ± 1.4 dBi with a 3 dB gain bandwidth of 24–27.7 GHz and a radiation efficiency of 78% were accomplished. [ABSTRACT FROM AUTHOR]

This article proposes a design of waveguide slot arrays with asymmetric iris to achieve broadband properties with high polarization isolation for E-band wireless backhaul systems. The proposed subarray of $2\times2$ radiating slots is excited by two-layered feeding networks carrying two orthogonal waves, and the asymmetric iris is inserted at the intersection where the waves merge. For verification, a prototype with $16\times16$ radiating slots is fabricated, and its antenna characteristics are measured in an anechoic chamber. The fabricated antenna has a bandwidth of 13 GHz at Port 1 and 10.5 GHz at Port 2 for voltage standing wave ratio (VSWR) ≤ 2.6, and the isolation between two ports is greater than 30 dB within the target frequency bands. The average bore-sight gains of the two ports are 30.85 and 31.67 dBi, and the half-power beamwidths are 3.5° and 3.25°. We also fabricate another prototype with $64\times64$ radiating slots for a field test. The proposed prototype is capable of maintaining the received power to be greater than 15 dB for an effective isotropic radiated power of 40.7 dBm at 25 m, which demonstrates that the proposed antenna is suitable to replace current parabolic dish antennas with a reduced profile. [ABSTRACT FROM AUTHOR]

Based on a newly proposed planar Yagi antenna with magnetic and electric dipoles, a compact $1\times 4$ broadband dual-polarized (DP) array with endfire radiation is designed in this paper. The magnetic Yagi antenna operates on the vertical polarization while the electric one operates on the horizontal one. The compact configuration of $0.5\,\,\lambda _{0}\times 0.63\,\,\lambda _{0}\times 0.09\,\,\lambda _{0}$ benefits from the novel half-mode magnetic Yagi antenna and the arrangement with the electric Yagi antenna. The broadband characteristic comes from the directors of the magnetic and electric Yagi antennas and the reflector of magnetic Yagi antenna. The simulation and the measurement verify this design. The measured common bandwidth of $\vert S_{11}\vert < -10$ dB for both polarization ports is 23.8–30.1 GHz (23.7%), and the gains vary between 3 dBi and 4 dBi within 24.2–30 GHz band range. The $1\times 4$ DP array with $0.5~\lambda _{0}$ element space has the beam scanning range of ±43 ° at the endfire direction and the gain of higher than 7.1 dBi. The scanning performances are experimentally validated by two phase-shift feed networks for 0 ° and 30 ° main beam directions. The proposed endfire DP array has the good features of compact structure, a low profile and no clearance requirement, which is easy to integrate in 5G terminals.

For the first time, a millimeter-wave dual-polarized dielectric resonator (DR) reflectarray fabricated by three-dimensional (3D) printing with high relative permittivity materials is presented. The unit cell of the reflectarray is composed of two elliptical DRs orthogonally placed in the center. A base layer of dielectric slab at the bottom of the unit cell is for fixture and connection with its adjacent elements. For each polarization, only the length of the long axis of one elliptical DR is varied independently to obtain the required reflecting phase response. Due to the orthogonality, high isolation and design independence between the two polarizations can be also obtained. A dual-polarized square DR reflectarray with $16\times16$ elements working in the Ka-band was designed, printed, and measured for demonstration. A measured peak antenna gain of 22.53 dBi was obtained, achieving a gain enhancement of 7.43 dB as compared with that of the feed horn.

A codesign dual-polarized patch antenna operating in dual compressed high-order modes and solar cells is proposed for green communication. The solar cell patch antenna is proposed for enhancing gain, wideband communication, and powering for wireless sensors. First, to enhance the gain of the antenna and the ability of optical energy harvesting, the antenna resonates at the high-order compressed modes. Second, the solar cell works in the direct-current loop, and the antenna works in the radio frequency loop separately. A differentially coupling-fed structure and two rows of vias are employed, which are beneficial to bandwidth and prevent the two loops from interfering with each other. Intrinsic isolation is achieved without any extra circuits. Next, a parametric study is exhibited as the antenna optimization guideline. By measuring the prototype experimentally performances, the design approach and the principle are validated. The measured results photoelectric experiment confirmed the ability of the solar cell antenna to convert luminous energy into electrical energy. In the desired operating band (4.8–5 GHz), the radiation performance of the proposed dual-polarized solar cell antenna is higher than 8.6 dBi for 5G communication. [ABSTRACT FROM AUTHOR]

We propose a dual-polarized leaky-wave antenna (LWA) with orthomode based on a metallic square waveguide for broadband endfire radiation applications. Several double-sided slots acting as radiation elements are notched on the waveguide to produce an endfire pattern. To overcome the restriction associated with the endfire radiation condition of a linear array, a metallic core periodically loaded with pins is used to control the dispersion of the proposed double-sided-slot waveguide. By optimizing the height distribution of the loading pins along the longitudinal direction using a cosine function, stable endfire radiation can be achieved over a broad operating band. Moreover, dual-polarized radiation can be automatically implemented because of the rotational symmetry of the proposed LWA. Furthermore, two rectangular waveguides connected with a square waveguide are used as the orthomode transducer (OMT) of the proposed LWA. The numerical and experimental results verify that dual-polarized endfire radiation is achieved in the frequency range of 7.6–9.1 GHz with an isolation of higher than 45 dB. The realized gain achieved is in the range of 13–15 dBi with a cross-polarization level of below −30 dB. [ABSTRACT FROM AUTHOR]