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In this paper, we present the design, assembly, and test of a heterogeneously integrated dual-polarized 256-element 5G phased array covering 24$-$ 30 GHz. The design is based on a 64-element antenna-in-package tile designed using an organic substrate. This work represents one of the earliest examples of a heterogeneously integrated mmWave phased array module where each tile uses chips in three different substrate technologies to perform beamforming, frequency conversion, filtering, combining/splitting, and supply decoupling functions. The paper discusses the several challenges and system trade-offs for 5G mmWave phased arrays and illustrates the advantages of heterogeneous integration at the antenna-in-package level. The paper also covers, in detail, several practical aspects of phased array module design that are not well-described in existing literature, such as power domain modeling, module assembly, antenna feedline design, polarization isolation, and tile spacing. To demonstrate the efficacy of our design choices and techniques, we present exhaustive $\pm 360^\circ$ over-the-air beam characterization of the phased array antenna module demonstrating beam scanning over $\pm 70^\circ$ and very low cross-polarization leakage in E-/H-planes in both polarizations and in both TX and RX modes.

In this work, two identical ceramic plates formed a stacked dense dielectric patch antenna is introduced for implementing a dual-polarized antenna. The proposed stacked ceramic structure generates highly pure adjacent modes, achieving wide impedance bandwidth, high isolation, and stable radiation performance across the entire operating bandwidth. The antenna combines with the advantages of the dense dielectric patch antenna and dielectric resonator antenna to produce symmetrical field distributions without spurious waves on the antenna body, resulting in high purities of radiation and polarization. A prototype of the proposed antenna is fabricated and tested. Its measured and simulated results are in good agreement. The 42% operating bandwidth covers from 3.3 GHz to 5.15 GHz for the reflection coefficient $\le $ -10 dB and with high isolation across the entire operating bandwidth. With the merits of low profile, wide bandwidth, high isolation and stable radiation performance, the proposed dual-polarized stacked ceramic antenna is promising for 5G/B5G wireless communication system.

This paper proposed a low-profile dual-polarization wideband inverted-F fed stacked-patch semi-flexible antenna. The proposed antenna features a stacked-patch on the top PCB layer and two orthogonal inverted-F feed structures on the bottom PCB layer. Flexibility is achieved through the thin, flexible bottom PCB layer, while the rigid top PCB layer can be arranged to prevent collisions between adjacent cells, allowing the array to bend easily. Two orthogonal inverted-F feeds share the same flexible PCB layer, enabling a low-profile dual-polarization antenna design. Polarization in x-direction is achieved using the single-ended inverted-F feed, while polarization in y-direction is achieved using the differential-ended inverted-F feed. Simulations were conducted to examine the impact of bending the flexible bottom PCB layer on the antenna performance. Key parameters of the proposed antenna were studied and a prototype was fabricated to validate the design concept. Measurement and simulation results are in good agreement. The thickness of the proposed antenna is $0.067~\lambda $ at the lowest operating frequency and the bandwidth is 15%. Measured isolation between the two ports is 26 dB.

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This article introduces a unique design approach for a compact in‐band full‐duplex (IBFD) antenna with good isolation in a wider bandwidth at the 2.4 GHz WLAN. The meander slot baluns are innovatively constructed in the feeding network, one balun on the top substrate layer and the other on the bottom substrate layer of the ground, to realize double differential feeding and polarization diversity. The metallic vias that connect one of the baluns in the feeding network with the co‐radiating patch further reduce the antenna's overall size. The balun's neutral coupling characteristics of differential potentials, which reduce the leakage currents by creating null potential, and differential filtering, which suppresses the leakage currents by non‐coupling fields, generate high isolation in the antenna. The designed balun offers a stable differential feed with a trivial magnitude and phase imbalances of (0.04–0.06) dB and ±10 $\pm {1}^{0}$, respectively. The antenna offers a minimum isolation of 78 dB with a wider bandwidth of 130 MHz. The far‐field measurement shows broadside radiation with low cross‐polar levels of less than −32 dB. A prototype is fabricated on FR‐4 substrate layers with an overall size of (0.8 × 0.8 × 0.012)λ0 ${\lambda }_{0}$ (λ0 ${\lambda }_{0}$ is the free space wavelength of the frequency f0=2.4 ${{f}}_{0}=2.4$ GHz) to validate the proposed design performance. The measured results of the prototype properly correlate with the simulated results. [ABSTRACT FROM AUTHOR]

Summary: This paper presents two different configurations of ±45° dual‐wideband dual‐polarized (DWDP) antennas. The antenna comprises eight end‐loaded broadband dipoles grouped into two sets based on the bands of operation. The high‐frequency dipoles are strategically placed within the low‐frequency ones to form the elementary unit. Further optimization has been performed on the elementary unit in terms of the radiator placement to suppress sidelobe levels for array formation. Both configurations are meticulously fabricated using an all‐metal structure, demonstrating durability and the simplicity of fabrication. The antenna designs achieve ±45° polarization, high gain, satisfactory cross‐polarization discrimination (XPD), and wide impedance bandwidth covering 0.67–1.04 GHz and 1.54–3 GHz bands. Despite the nested configuration, mutual coupling is well within acceptable limits. Formation of the array based on the optimum elementary unit has been investigated by simulation, revealing reasonable gain enhancement and low sidelobe levels across all bands. This comprehensive approach yields a robust, high‐performing antenna configuration suitable for indoor distributed antenna system (IDAS) applications. [ABSTRACT FROM AUTHOR]

Dual‐polarization programmable metasurfaces can flexibly manipulate electromagnetic (EM) waves while providing approximately twice the information capacity. Therefore, they hold significant applications in next‐generation communication systems. However, there are three challenges associated with the existing dual‐polarization programmable metasurfaces. This article aims to propose a novel design to address them. First, the design overcomes the challenge of element‐ and polarization‐independent controls, enabling more powerful manipulations of EM waves. Second, by using more energy‐efficient tunable components and reducing their number, the design can be nearly passive (maximum power consumption of 27.7 mW), leading to a significant decrease in the cost and power consumption of the system (at least two orders of magnitude lower than the power consumption of conventional programmable metasurfaces). Third, the design can operate in a broad bandwidth, which is attractive for practical engineering applications. Both the element and array of the metasurface are meticulously designed, and their performance has been carefully studied. The experiments demonstrate that 2D wide‐angle beam scanning can be realized. Moreover, secure communication based on directional information modulation can be implemented by exploiting the metasurface and an efficient discrete optimization algorithm, showing its programmable, multiplexing, broadband, green, and secure features. [ABSTRACT FROM AUTHOR]

The complex convergence of cold and warm ocean currents in the Nordic Seas provides suitable conditions for the formation and development of eddies. In the Marginal Ice Zones (MIZs), ice eddies contribute to the accelerated melting of surface sea ice by facilitating vertical heat transfer, which influences the evolution of the marginal ice zone and plays an indirect role in regulating global climate. In this paper, we employed high-resolution synthetic aperture radar (SAR) satellite imagery and proposed an oriented ice eddy detection network (OIEDNet) framework to conduct automated detection and spatiotemporal analysis of ice eddies in the Nordic Seas. Firstly, a high-quality RGB false-color imaging method was developed based on Sentinel-1 dual-polarization (HH+HV) Extra-Wide Swath (EW) mode products, effectively integrating denoising algorithms and image processing techniques. Secondly, an automatic ice eddy detection method based on oriented bounding boxes (OBB) was constructed to identify the ice eddy and output features such as horizontal scales, eddy centers and rotation angles. Finally, the characteristics of the detected ice eddies in the Nordic Seas during 2022-2023 were systematically analyzed. The results demonstrate that the proposed OIEDNet exhibits significant performance in ice eddy detection.

Copyright of Micronanoelectronic Technology is the property of Micronanoelectronic Technology 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.)

Abstract Dual‐polarization programmable metasurfaces can flexibly manipulate electromagnetic (EM) waves while providing approximately twice the information capacity. Therefore, they hold significant applications in next‐generation communication systems. However, there are three challenges associated with the existing dual‐polarization programmable metasurfaces. This article aims to propose a novel design to address them. First, the design overcomes the challenge of element‐ and polarization‐independent controls, enabling more powerful manipulations of EM waves. Second, by using more energy‐efficient tunable components and reducing their number, the design can be nearly passive (maximum power consumption of 27.7 mW), leading to a significant decrease in the cost and power consumption of the system (at least two orders of magnitude lower than the power consumption of conventional programmable metasurfaces). Third, the design can operate in a broad bandwidth, which is attractive for practical engineering applications. Both the element and array of the metasurface are meticulously designed, and their performance has been carefully studied. The experiments demonstrate that 2D wide‐angle beam scanning can be realized. Moreover, secure communication based on directional information modulation can be implemented by exploiting the metasurface and an efficient discrete optimization algorithm, showing its programmable, multiplexing, broadband, green, and secure features.

In this article, we present and illustrate a flip-chipbased antenna-on-package (AoP) concept for the development of 5G mmWave massive MIMO antenna arrays and frontend modules. Unlike conventional Antenna-in-Package concepts, our concept provides the flexibility to choose suitable and separate layer stack-ups and packaging materials for enabling the antennas and the frontend components to meet their respective specifications. To illustrate this concept, we designed, fabricated, and measured novel dual-polarized broadband AoP arrays in the 39 GHz frequency band for 5G mmWave MIMO applications. The array consists of 16 identical stacked patch elements. Each single antenna possesses a driven patch, which is vertically stacked to a parasitic element to improve the antenna performance. It is excited by two orthogonal probe-feds for dual polarization. Furthermore, we designed and optimized antenna arrays together with the solder interconnects used for mounting the antennas onto the multilayered interposer. Our results show that these interconnects could cause up to about 0.5 dB reduction in the realized gain of the antenna array. The fabricated antenna arrays were measured from 33 to 41 GHz. A peak gain of approximately 16 dBi was measured. Excellent correlation was obtained between all the measurement and simulation results. [ABSTRACT FROM AUTHOR]

This study introduces a compact, wideband dual-polarized suspended patch antenna designed for LTE700/LTE850/CDMA850/GSM900 applications, with a focus on achieving high isolation. The antenna design has two suspended patches that are excited in orthogonal directions using a modified crossed-slot configuration. The modifications applied to the crossed-slot significantly enhance the -15 dB impedance bandwidth, resulting in improved port isolation between polarizations. Both theoretical analysis and experimental testing confirm these enhancements, revealing an impressive -15 dB impedance bandwidth of 37% (688-1000 MHz) and port isolation exceeding 35 dB in the operating band. The antenna exhibits symmetric and directional radiation patterns in principle planes, with half-power beamwidths ranging from 55.32° to 65.61° and 61.79° to 66.84°. Antenna gain show exhibits variation in the range of 7.3-8.4 dBi across the measured frequencies. The compact size of the antenna, measuring 380 × 380 × 43.6 mm², makes it highly suitable for integration into commercially deployed base stations. Throughout the paper, we provide a detailed presentation of the antenna's geometry, feeding mechanism, parametric studies, and experimental results. The combined theoretical analysis and practical experimentation validate the success of the proposed antenna design, highlighting its potential for robust performance in a wide range of communication applications. [ABSTRACT FROM AUTHOR]

Monitoring marine oil pollution holds both practical and scientific significance. Synthetic Aperture Radar (SAR) is an active microwave remote sensing technique capable of all-weather and all-day with fine spatial resolution. However, under low wind conditions, rain cells and young ice are examples of look-alikes affect the accuracy of oil spill detection. Polarimetric SAR assumes a crucial role in this context, as it can extract abundant polarimetric features by polarimetric target decomposition. Drawing inspiration from this advancement, an improved polarimetric feature named relative feature based on Cloude-Pottier target decomposition was proposed. The Jeffries-Matusita distance indicates the substantial potential of the relative feature in detecting oil spills. The improved polarimetric feature within U-Net, FCN-8s, and DeepLabv3+ResNet-18 for oil spill detection using polarization SAR images. Experiment results demonstrated that the relative feature has superior performance compared to other polarimetric features and obtained the highest accuracy and dice within U-Net compared to the other two models. These findings introduce promising concepts for achieving rapid and precise detection of oil spills in future applications. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicle-based photon-counting ocean bathymetric light detection and ranging (LiDAR) systems rapidly acquire topographic data from islands, reefs, and shallow waters. However, the bathymetric ability of seabed topography is affected by high backscattering from the sea surface owing to its proximity, and no suitable imaging models are available. Herein, we designed a novel ray approach for bathymetry based on a dual-polarization photon-counting LiDAR. Based on the transmission characteristics of light, a dual-polarization channel strategy was proposed, and the data from two channels in vegetation, sand, and shallow and medium-depth waters were compared. Based on the ray tracing method, imaging models of the water surface and depth for light and small photon-counting LiDAR were established. Shallow-water experiments were conducted near Jiajing Island, Hainan, China, to verify the accuracy of the LiDAR bathymetry data by shipborne single-beam sounding data. The results indicate that the vertical polarization channel data had a high signal-to-noise ratio in the terrestrial part, while the horizontal polarization channel had a better water surface backscatter suppression effect and strong bathymetry ability in the water part. The detectable depth was approximately 8 m in the experimental area. The MAEs of the depth values of the LiDAR point cloud before and after refraction correction relative to the single beam depth measurement values were 1.08 and 0.09 m, respectively. And the RMSEs before and after correction were 1.12 and 0.11 m, respectively.

This paper describes a design of dual-polarized composite patch-monopole antenna with reconfigurable radiation pattern. The design consists of a double differential-feed patch loaded with four vertical monopoles symmetrically. The monopoles are connected to or disconnected from the ground plane (GND) by changing the ON/OFF states of p-i-n diodes. By adjusting the connections between the monopoles and GND, the pattern reconfigurability (i.e., one widebeam and three narrow-beam modes) can be achieved for each polarization. The proposed antenna can switch the beam in two dimensions separately $(xz-$ and $yz-$ plane). The proposed antenna is characterized computationally and validated experimentally. The measurements result in an overlapping 10-dB return-loss bandwidth of $2.40 - 2.51$ GHz and a port-to-port isolation ≥20 dB in all the modes. In the far field, the prototype can deploy switched beam flexibility. Its radiation characteristics are confirmed by the far-field measurements, which shows the reconfigurable patterns for both polarizations.

We present a novel concept of a millimeter-wave patch antenna that integrates the functions of a dual-polarized antenna and a capacitive proximity sensor to detect the state of a hand grip on a smartphone and compensate for the effect. The antenna has a dual-polarized, proximity-coupled, square patch structure, and acts as a proximity sensor by utilizing the change in capacitance of the patch when the user’s hand approaches. By observing the change in capacitance at the center of a square patch operating in two fundamental TM modes, antenna and sensor functions can be performed concurrently and without mutual interference. The antenna is designed using a low-cost four-layer FR-4 substrate and fabricated using a cost-effective standard printed circuit board (PCB) process. The antenna is configured as a $1 \times 8$ array, and after mounting it on a smartphone model, the gain, beam steering performance, and change in capacitance according to hand proximity are predicted and measured. The peak gain measured at 28 GHz exceeds 11.8 dBi, with a gain variation of less than 2.2 dB within the 5 G 257 band ( $26.5-29.5 \mathrm {GHz}$ ). The measured capacitance change due to hand proximity is 130 fF, which is sufficient for real-time detection of the hand grip state. An example of improvement in the gain of the proposed antenna by detecting the hand grip state is presented through a simulation.

To expand the channel capacity of a traditional single-polarization reconfigurable antenna, a design method for a dual-polarization reconfigurable microstrip antenna loaded with a passive metasurface was proposed. By utilizing the equivalent circuit method and characteristic modeling analysis, this method can provide guidance for designing an integrated antenna with adjustable dual-polarization. An antenna with an operating frequency of 3.5 GHz is designed, which is composed of four layers, from top to bottom: metasurface layer, radiation patch layer, feed layer, and reflector layer. By rotating the metasurface layer to adjust its relative position with other fixed layers, the designed antenna can achieve a mutual transformation between orthogonal dual-linear polarization (Horizontal polarization/Vertical polarization) and orthogonal dual-circular polarization (Left-handed circular polarization/Right-handed circular polarization), while ensuring antenna performance. The simulation and measurement results of the designed antenna demonstrate that it possesses competitive gain and polarization isolation performance, with a 3 dB axial ratio bandwidth reaching 17.4% in the dual-circular polarization state.

Sentinel-1A/B data are crucial for retrieving numerical information about surface phenomena and processes. Coregistration of terrain observation by progressive scans (TOPS) data is a critical step in its application. TOPS data must be fundamentally co-registered with an accuracy of 0.001 pixels. However, various decorrelation factors due to natural vegetation and seasonal effects affect the coregistration accuracy of TOPS data. This paper proposed an enhanced spectral diversity coregistration method for dual-polarimetric (PolESD) Sentinel-1A/B TOPS data. The PolESD method suppresses speckle noise based on a unified non-local framework in dual-pol Synthetic Aperture Radar (SAR), and extracts the phase of the optimal polarization channel from the denoised polarimetric interferometric coherency matrix. Compared with the traditional ESD method developed for single-polarization data, the PolESD method can obtain more accurate coherence and phase and get more pixels for azimuth-offset estimation. In bare areas covered with low vegetation, the number of pixels selected by PolESD is more than the Boxcar method. It can also correct misregistration more effectively and eliminate phase jumps in the burst edge. Therefore, PolESD will help improve the application of TOPS data in low-coherence scenarios.

The limitations of conventional sensors have made array antennas increasingly crucial for gathering information and communication applications in intelligent transportation and communication systems. Compact cylindrical arrays are particularly favored for their ability to achieve azimuth angle scanning. However, the substantial mutual coupling effect between the elements on curved surfaces and its implication for these arrays remain unclear, which is a key factor to consider when such arrays are used for multibeam applications. This study investigates the effect of mutual coupling in a dual-slant-polarized cylindrical array. The results showed that mutual coupling is predominantly observed among the closely located elements, and it is essential for achieving an ultra-wide bandwidth. The study also analyzes the impact of mutual coupling on the scan impedance and radiation characteristics for multibeam applications and reveals that these arrays exhibit robust multibeam capability, hence having great potential for use in sensing and communication applications. [ABSTRACT FROM AUTHOR]

A dual-polarized broadband coupled feed dipole antenna loaded with artificial magnetic conductor (AMC) structure is proposed. The proposed AMC structure with 4x4 elements shown in this paper consists of four perfect electrical conductor (PEC) rectangular strips and a ring to reduce the profile height of the dual-polarized dipole antenna. In addition, the dual-polarization antenna adopts coupling feed microstrip to excite two pairs of bow-tie patch. The overall size of the coupling feed dipole antenna is 1.1λ0x1.1λ0x0.09λ0 at 5.5 GHz. Measured results shows that the proposed dual-polarization antenna loaded AMC exhibit a 25.2% common working bandwidth (4.75-6.12 GHz). The isolation is less than -14 dB, and the peak gain is 10.6 dBi. This dipole antenna with AMC structure has the virtues of low profile, wide band, and good radiation performance and it has the potential to be used in C-band communication. [ABSTRACT FROM AUTHOR]

A novel dual‐polarization (DP) rectangular horn with equal elliptical beams for synthetic aperture radar application is proposed. The DP elliptical beams with same beam width are achieved by loading groove with coupling gap in the rectangular horn narrow side. The key parameters of the proposed horn are analyzed and a prototype operated at S band is fabricated and measured. Good agreements between simulated and measured results are obtained. What's more, an elliptical reflector antenna based on the proposed horn feed array is devised. Compared with the common rectangular horn, the reflector with the proposed horn owns better DP radiation performance. [ABSTRACT FROM AUTHOR]

A strip‐typed patch antenna covered with a dielectric is studied. The antenna is excited with a differential feeding mechanism to obtain a low cross‐polarization level. When the patch antenna is totally covered with a dielectric, it can be operated at lower frequencies without tuning antenna dimensions. The simulated results show that as the relative permittivity of the dielectric is increased from 1 to 9.2, the antenna operation frequency is reduced from 4.25 to 2.38 GHz, and the cross‐polarization level is lower than −25 dB for each operation frequency. Based on such an antenna, a 1 × 8 dual‐polarized phased array is developed. The simulated results indicate that for each polarization mode, the gain variations of the array are less than 2 dB when the main beam is scanned from 60° to −60°; bedsides, a cross‐polarization level of less than −20 dB is also achieved. An array prototype is constructed, and measured data validate the simulated results. [ABSTRACT FROM AUTHOR]

The implementation of antenna arrays, beamforming, and millimeter-wave communication in a 5G network requires a novel approach to testing the radio performance of the devices. Over-the-air testing is a practical solution for measuring the radio performance of next-generation wireless systems. This paper presents the analysis and design of the dual-polarized Vivaldi antenna for over-the-air testing of a 5G base station for the frequency range spanning from 1.4 GHz to 6 GHz. The designed antenna consists of two elements arranged in an orthogonal fashion. The two dual-polarized Vivaldi antenna prototypes are modeled: one with an offset between the antenna elements and the other without an offset between the antenna elements. The wideband antenna is mainly characterized by an acceptable reflection coefficient (S11) over the desired operational bandwidth. The simulation results show S11 less than –10 dB across 1.4 to 6 GHz frequency range in both prototypes. The CST Studio Suite EM simulator is used to create and simulate the proposed antenna utilizing the Rogers RO4350B substrate, which has an overall size of 86 90 0.5 mm3. The proposed antenna will be used at the UE side inside the anechoic chamber to test 5G base station over the air in terms of throughput and mobility. The compact size and low cost are the key features of this antenna. Low cost is achieved by using cheap dielectric material. [ABSTRACT FROM AUTHOR]

A dual-polarized filtering Fabry–Perot antenna (FPA) with high selectivity and high isolation is proposed for in-band full-duplex (IBFD) applications. The proposed antenna utilizes a square patch as the feeding element, which is fed by a double differential-fed scheme for dual-polarized radiation with high isolation. The patch is loaded with a symmetrical cross-slot and four shorting pins for a broad passband filtering feature. To enhance broadside gain across a wide frequency range, the patch is incorporated with a partially reflecting surface (PRS), which is composed of two complementary cross-slot and patch arrays. Moreover, the frequency selectivity of PRS is exploited to improve the filtering characteristic. The double differential feeds are realized based on out-of-phase power dividers, which are combined with simple low-pass filters to further improve the out-of-band suppression. The final design was fabricated and measured. The measurement results show excellent results with a 10-dB return loss bandwidth of 21.5% (4.91–6.09 GHz), isolation of greater than 40 dB, peak gain of 13.7 dBi, out-of-band suppression level of better than 27 dB, and a cross-polarization level of less than −27 dB.

In this paper, a dual‐polarized multibeam antenna in X‐band is designed and physically fabricated using a parabolic reflector. The antenna consists of a feed array and a metal reflector. A dual‐polarized microstrip antenna array combining two design approaches, T‐coupled feed and defective ground structure, is adopted as the feed array to improve polarization isolation. In addition, the electromagnetic bandgap structure is loaded between the antenna units to reduce the mutual coupling and improve the isolation between the units. A nine element of the highly‐isolated dual‐polarized microstrip antenna array is designed to be placed on the focal plane of the parabolic reflector as the feed, and the beam deflection is realized by using the lateral defocus effect of the parabolic plane, which can finally realize nine single beams covering a 30° scanning range in both horizontal and vertical polarization modes. Based on the scanning state of multiple point beams, this paper uses the Fourier series for beam assignment to form a flat‐top beam with a wide scanning angle. The application of the antenna with two operating modes of wide beam and multibeam to navigational satellite systems can greatly improve the accuracy and efficiency of navigation. [ABSTRACT FROM AUTHOR]

This paper proposes a low-profile highisolation dual-polarization array antenna operating in the L/S band. The radiating unit of the array antenna adopts U-shaped bending dipoles to realize the staggered arrangement of high- and low-band units, and is connected to the feeding network by a coaxial cable. To achieve the non-influence of high-band and low-band feed networks, multi-layer printing technology is used and grooves are etched on the metal plate. In order to reduce the coupling of the high- and low-band dipoles at low frequency, a bandpass filter is added to the highband feed network, which greatly improves the isolation at low-frequency. The measured results show that the impedance bandwidth of the array is 4.5% (0.971-1.015 GHz) and 7.5% (1.89-2.04 GHz), with gains of 15 and 19 dBi at 1 GHz and 2 GHz, respectively. And the isolation between the dual-polarized ports more than 50 dB and 35 dB was achieved at 1 GHz and 2 GHz, respectively. The proposed array will have practical value in L/S band full-duplex wireless communication systems. [ABSTRACT FROM AUTHOR]

Synthetic aperture radar (SAR) remote sensing technology has the advantage of all-weather observation and can acquire time-series images with crop growth period, which has great potential for applications such as crop phenology analysis. However, available studies primarily focus on conducting statistical and crop growth analyses based on the polarization or backscatter intensities of SAR images, and the exploration of polarization scattering information in SAR images is not sufficient. To comprehensively reflect the polarization characteristics and scattering mechanisms of crop at different growth stages, we propose a new method for extracting vegetation descriptors from Sentinel-1 dual-polarimetric SAR data. The method combines the backscattering intensity and polarization decomposition information to construct a normalized index q , which is used to generate three vegetation descriptors: the co-pol purity parameter (m cp ), the pseudo-scattering angle (θ cp ), and the pseudo-scattering entropy (H cp ). Further, a novel unsupervised clustering framework, founded on H cp and θ cp , has been proposed. This framework establishes six zones (named as Z1 to Z6) representing distinct physical scattering mechanisms, and by statistically sampling point data, it can determine the growth stage of the crops For validating the performance of the proposed vegetation descriptors and clustering framework, we conducted a three-year experiment using four crops from two publicly available datasets, namely wheat and canola from the Carman in Canada (Test site-1), corn and soybeans from Iowa in the United States (Test site-2). The experimental results indicate that m cp , θ cp , and H cp exhibit regular changes at different growth stages of crops from planting to maturity, with m cp and θ cp gradually decreasing while H cp gradually increasing. Within the entire phenology window, θ cp changes by approximately 42°, while both m cp and θ cp varies by about 0.9, and the sampling points shift from the Z2 to the Z5 zone. The vegetation descriptors are highly sensitive to the growth status of crops, and the clustering framework can also effectively respond to different growth stages of vegetation. Furthermore, the vegetation descriptors and clustering framework proposed in this study have the potential for extended application to different crop types and other polarimetric SAR data sources. [ABSTRACT FROM AUTHOR]

Based on the quality control of observational data, the heavy hailstorm that occurred in Yangjie Town, Weining County, Guizhou Province on June 28, 2018 is analyzed. The study combines a fuzzy logic hydrometeor identification algorithm with the mesoscale numerical model WRF and uses the X-band dualpolarization radar located in Xueshan Town, Weining County, Guizhou Province. The results show that there is a good consistency between the observation and model simulation results of this hail process, which mainly goes through four stages: development, ripeness (hail formation), ripeness (hail shooting) and attenuation (disappearance). (1) Development: Caused by the riming between ice crystals and surrounding super-cooled cloud water, low-density graupel (LDG) is formed near the cloud layer of -20 ℃ (5.0~6.8 km). Caused by the riming between aggregation (AG) and surrounding super-cooled cloud water, high-density graupel (HDG) is formed near the cloud layer with a terrain clearance of 2.6~4.2 km. (2) Ripeness (formation): AG is the main source of graupel embryo for LDG and HDG. The rain mixed with hail (RH) is initially formed near the cloud layer of - 20 ℃ (4.2~6.8 km) and it is caused by a small amount of HDG which collides with and freezes the super-cooled cloud water. (3) Ripeness (hail shooting): LDG is largely formed by coagulation. HDG develops from two sources: one is the riming with the AG particles (3.4 ~ 6.0 km) as the HDG embryo source, and the other is the gravity sedimentation by the top LDG particles (6.8 ~ 9.3 km), in which the particles develop into a large amount of HDG through coagulation with other ice phase particles during sedimentation. Finally, the HDG develops into the RH. (4) Attenuation (disappearance): HDG grows slowly by colliding with the super-cooled cloud water near the cloud layer of 0 ℃ (3.4 km). While falling continuously, LDG and HDG are gradually converted into liquid precipitation due to obvious melting effect. [ABSTRACT FROM AUTHOR]

The International Collaborative Experiment during the PyeongChang Olympics and Paralympic winter games 2018 took place in the PyeongChang region of South Korea. The main goal of this field campaign was to study winter precipitation in an environment that has complex terrain. The NASA dual-frequency, dual-polarization, Doppler radar (D3R) was calibrated and deployed in this field campaign. The positioning error of the radar was calibrated to be within 0.1°. The D3R was deployed for more than four months and was able to capture many interesting snowfall events along with a few rain events. In this article, the deployment and performance of the D3R during the campaign are discussed. The snowfall events captured by the D3R are discussed in detail to interpret the microphysics from a radar's perspective. The reflectivity–snowfall rate relationship is derived at the Ku band, and the snow accumulation computed is in good agreement with a precipitation gauge that was deployed near the radar. The benefit of the dual-frequency ratio for identifying the precipitation particle types is briefly introduced using the data from a large snow event on 28th February 2018. The vertical profile D3R data for this snow event are studied for detecting the presence of pristine-oriented ice crystals in the mixed hydrometeor phase conditions. Various other instruments, such as X-band radar and disdrometers, were deployed in the campaign. The D3R data are compared with the MxPOL X-band radar, and the reflectivity values match within a couple of dB in the common volume region.

A wideband and dual-polarized dipole antenna design technique is presented. The proposed antenna employs two sets of dipole elements in orthogonal configuration and separated by a dielectric layer. The dipole elements are excited with two separate substrate-integrated-coaxial feeds to achieve high port-to-port isolation and the overall antenna stackup is enclosed in a substrate-integrated-waveguide (SIW) cavity. To validate the proposed substrate-integrated-coaxial fed dual-polarized antenna design method, a prototype antenna was fabricated using standard multi-layer printed circuit board (PCB) manufacturing technologies to operate in the Ku-band. Measured and simulated results exhibit that the designed antenna has a wide impedance bandwidth of less than -10dB reflection coefficients at 10.28-14.8GHz and the port-to-port isolation between the two orthogonally polarized dipole antenna ports is greater than 20dB at most frequencies, making it suitable for many applications such as satellite communications. The antenna has a relatively stable gain pattern with a gain value of 5.5-6.5dBi and a low cross-polarization level (lower than 16dB) over the operating frequency range.

This paper provides new designs and realizations of leaky-wave (LW) metasurface (MTS) antennas fed at multiple points. The design technique is based on the direct integral-equation solution by the Method of Moments (MoM). The unknown is no longer the current distribution, but the impedance profile itself. The method can be used to generate any shaped radiation pattern in amplitude, phase, and polarization, provided that the antenna area and the feeder illumination are consistent with the shape of the desired radiation pattern. The algorithm can also be used to design multi-functional antennas (multibeam, multiband, dual-polarizion, etc). While multiple feeds are traditionally used to implement multiple fonctionnalities, they may also be required for the efficient generation of a single shaped beam, thus leading to a higher surface-wave (SW) to LW conversion efficiency. The present paper shows for the first time, two realizations of MTS design with the integral equation formalism, which require the usage of multiple feeds: a circularly polarized sectoral conical beam and a dual-polarized broadside beam MTS antenna. The good comparison between measurements and numerical predictions shows the effectiveness of the design method.

A novel high-isolation dual-polarized in-band full-duplex (IBFD) dielectric resonator antenna (DRA) for satellite communications using a decoupling structure is proposed. Good isolation between transmit and receive ports is achieved by placing two identical linearly polarized resonators orthogonal to each other. Each resonator consists of a main rectangular dielectric resonator of the dielectric constant of 10 and is loaded by a thin dielectric slab of lower permittivity of 5 to broaden the matching bandwidth further. The isolation is further improved by loading an absorber and etching several slots in the ground plane. Finally, the proposed DRA is fabricated and measured to validate the concepts. Measurement results show high isolation of more than 50 dB over the desired operating bandwidth from 23.04 GHz to 24.08 GHz (ka-band) with a peak gain of about 8.93 dBi and 8.09 dBi for Port 1 and Port 2, respectively. In addition, the proposed IBFD DRA provides 11.87 GHz and 4.84 GHz isolation bandwidths over 25 dB and 30 dB, respectively, making it a potential candidate for mm-wave terrestrial applications.

This paper proposes a novel design and the experimental characterization of a dual-band, shared aperture transmitarray operating in dual linear polarization at K/Ka-band. It is based on a 1-bit unit-cell realized using five metal layers and demonstrating low transmission loss (< 2 dB). By combining the polarization rotation method and the stacked patch architecture, the proposed shared aperture transmitarray is able to shape the beam independently in both K- and Ka-bands. A $40\times 40$ -element prototype has been optimized by using an ad-hoc numerical tool and fabricated. The experimental results are in excellent agreement with the numerical and full-wave electromagnetic simulations. This flat lens is illuminated by two standard gain horns with a nominal gain of 10 dBi. They are mounted in orthogonal polarization and located at the same distance from the aperture (110 mm). A peak gain of 27.1 and 29.9 dBi has been achieved, respectively, at 18.7 and 28.5 GHz corresponding to an aperture efficiency of 26.1 and 22.3%. The possibility to steer mechanically the radiation pattern has also been experimentally proven. The proposed antenna system is a low-cost and compact solution for future vehicular broadband SatCom applications.

This paper presents a low-profile, high-isolation, dual-polarized antenna with broadband and widebeam characteristics. The antenna consists of a square patch fed by double differential-fed scheme for the high-isolation dual-polarized radiation. The patch is loaded with four top-hat monopoles to not only broaden the beamwidth, but also generate an extra resonance, which is utilized to improve the operational bandwidth. For verification, an antenna prototype with $0.096\lambda _{0}$ -height at the center frequency of 2.5 GHz has been fabricated and measured. The measurements result in a 10-dB return loss bandwidth of 13.8% (2.36 - 2.71 GHz), an isolation of ≥ 43 dB, and excellent widebeam dual-polarized radiation, i.e., at 2.4 - 2.6 GHz, its half-power beamwidths are ≥ 180° and ≥ 120° in the E- and H-planes, respectively.

A broadband dual-polarized crossed dipole antenna is proposed in this paper. To achieve a wide impedance bandwidth and low-profile configuration, a novel bow-tie balun is applied to this antenna. Firstly, the working mechanisms of both bow-tie baluns and the antenna are introduced. Then, the parametric study and design guidelines are presented. Finally, the optimized antenna is fabricated, measured, and analyzed. The simulated and measured results show that the antenna has a wide impedance bandwidth from 2.42 GHz to 6.48 GHz. The fractional bandwidth is 91.2%. Moreover, within the whole band, the E-plane and H-plane radiation patterns are stable. The port isolation is greater than 20 dB, and the cross-polarization discrimination ratio is better than 25 dB. The proposed antenna achieves a realized gain of 7.5   d B i   ±   0.5   d B i . It can be a good candidate for sub-6 GHz wireless communications or short-range radar applications. [ABSTRACT FROM AUTHOR]

A broadband dual‐polarized antenna array with excellent impedance matching and stable radiation performance is proposed. The array comprises four folded‐dipole antenna elements. Two trapezoidal baluns are used to excite the folded‐dipole antenna to obtain good impedance matching and generate a ±45°‐polarized radiation pattern. To improve the impedance matching and achieve steady radiation performance, a square parasitic director is used and placed above the folded dipoles. The antenna element realizes a broad bandwidth of 76.9% (voltage standing wave ratio [VSWR] < 1.5 from 1.69 to 3.8 GHz) and high isolation of 28 dB. Then an antenna array comprised of four elements is designed. It is fed by two miniaturized 1‐to‐4 power divides. Several metal baffles are added between adjacent elements to reduce the mutual coupling. The array achieves a broad bandwidth of 78.4% (VSWR < 1.5 from 1.66 to 3.8 GHz), high isolation of 25 dB, stable half power beamwidth in the E‐plane within 65° ± 5°, and high gain within 12–15 dBi. [ABSTRACT FROM AUTHOR]

Due to climate change in recent years, the degradation of most glaciers on the Qinghai-Tibet Plateau has accelerated the expansion of glacial lakes. Based on the polarization entropy difference between water and non-water signals, this paper studies the classification method of glacial lake in snowmelt period by using the dual-polarization time series synthetic aperture radar (SAR) images as data sources, and proposes a method for extracting and dynamically monitoring glacial lake based on the normalized polarization entropy ratio of dual-polarization SAR images. In order to verify the feasibility of the method, the Sentinel-1 dual-polarization image sequence of ESA was selected to carry out the dynamic extraction of glacial lakes and the analysis of long-term temporal variations on a time span of 4a for the typical experimental area located in the glacier basin of A'nyemaqen. The spatial and temporal changes of the glacial lake at the end of the A'nyemaqen glacier during 2019-2022 were successfully obtained through experiments, and then it was found that the area of the glacial lake near 4a was decreasing. [ABSTRACT FROM AUTHOR]

We have developed the first low-loss, dual-polarization, asymmetric Mach-Zehnder interferometer (AMZI) chip for phase-coding quantum key distribution (QKD) using silica planar lightwave circuit technology. The transmitter and receiver modules have a polarization extinction ratio greater than 20 and 15 dB, respectively. Using a birefringent Mach-Zehnder interferometer, a polarization beam splitter is integrated into the receiver chip, while the polarization rotation function is obtained via a half-wave plate thin film. The receiver chip is entirely passive and has an excellent fiber C fiber loss of 1.90 dB, while the transmitter’s AMZI contains thermo-optical electrodes for adjusting the output pulses’ relative phase and intensity ratio. The chips are evaluated to have an interference visibility of greater than 98% across a broad temperature range, demonstrating their suitability for quantum key distribution applications. [ABSTRACT FROM AUTHOR]

To solve the problem of range-spread targets detection in non-Gaussian clutter for dual-polarimetric radar systems, a novel dual-polarimetric persymmetric detector based on the two-step generalized likelihood ratio test (GLRT) is proposed. First, the target signal is modeled as a multi-rank subspace signal, and the clutter is modeled as a compound Gaussian model with deterministic unknown texture. Then, by taking polarimetric and persymmetric characteristics of the clutter into account, the detection performance of the proposed detector is obviously improved. Finally, through the verification via both simulated data and measured data, it is shown that the proposed detector poses better detection performance in comparison with the existing nonpolarimetric detectors. Due to the complexity of the detector form, the analytical expression of false alarm probability cannot be derived. Therefore, we verified the constant false alarm ratio (CFAR) characteristic of the proposed detector through a simulation experiment. [ABSTRACT FROM AUTHOR]

The National Weather Service has initiated an effort to upgrade the scan strategy of the operational Weather Surveillance Radar-1988 Doppler (WSR-88D) to improve its hydrometeorological applications. The lowest scan elevation angle has been changed from 0.5° to 0° (or even lower in the future) for some WSR-88D stations. Using the KMUX WSR-88D radar deployed in mountainous terrain in Northern California as an example, this letter quantifies the impacts of lowering the minimum scan elevation angle of WSR-88D radar on surface rainfall mapping, with an emphasis on shallow orographic precipitation. In order to estimate surface rainfall using radar observations, polarimetric radar rainfall relations are established using local disdrometer data, which are then implemented with the KMUX radar observations at 0° and 0.5° scan elevation angles to derive rainfall estimates. Comparative evaluation of the radar-based rainfall estimates using rainfall measurements from surface rain gauges has demonstrated the superior performance of the lower scan elevation angle. When the distance from the radar is long (i.e., when the radar beam is likely within or above the melting layer), the improvement gained by the 0° scan relative to the 0.5° scan is 16.1% and 19.5% in terms of the normalized standard error (NSE) and the Pearson correlation coefficient (CORR), respectively. [ABSTRACT FROM AUTHOR]

Ground-penetrating radar (GPR) has been widely applied to the detection and delineation of buried targets in the subsurface. Compared with conventional single-channel GPR, polarimetric GPR has been proven to possess an improved ability to detect and characterize an elongated object in the subsurface. This letter proves that the scattering signals from a cylinder in two orthogonal polarization channels have a phase difference of about 90° when its diameter-to-wavelength ratio is about 0.05–0.33. Consequently, a polarization-difference imaging method, which shifts the VV component by −90° and subtracts it from the HH component, is proposed for the improved detection and imaging of a subsurface elongated object. Its effectiveness is verified by numerical, laboratory, and field tests on buried rebars and pipes. The signal-to-clutter ratios of the reconstructed GPR images can be improved by up to 4.5 dB by considering the phase difference between the dual-polarization components. [ABSTRACT FROM AUTHOR]

In this work, a heterogeneous 6 × 4 dual‐polarized MIMO antenna array was developed to achieve antenna elements with uniform 10 dB‐beamwidth (120° ± 10°). To constrain the 10 dB‐beamwidth, two types of antenna elements are designed and properly placed in the antenna array according to the nonuniform electromagnetic coupling environment. A nonuniform aperiodic metasurface with equivalent capacitance loading effect is then proposed to compensate the inductance of the heterogeneous antenna array. It results in a low‐profile height of 0.17λL and good impedance matching over 40% bandwidth. The unit cells in the metasurface are arranged with non‐uniform spacing to achieve uniform 10 dB‐beamwidth of the antenna elements in an antenna array environment. Both simulation and measurement results validate that the proposed design achieves stable radiation patterns and uniform 10 dB‐beamwidth (120° ± 10°) over a wide frequency band of 1.8–2.7 GHz. Because of these attractive features, the proposed antenna array becomes a promising candidate for massive multiple‐input and multiple‐output base station antennas. [ABSTRACT FROM AUTHOR]

A miniaturized dual-polarized smartphone antenna based on tightly coupled dipole array (TCDA), applying to 5 G millimeter-wave (mmW), is presented. The antenna element has a size of 2.94 mm × 3.05 mm × 0.94 mm and covers a bandwidth of 91.5% and 88.4% with VSWR＜2 for pol-x and pol-y, respectively. To achieve low cost, compact size, and reduce the number of ports, a specific miniature feeding structure, using Γ-shaped coupling probes, is applied. The proposed smartphone antenna consists of eight elements with a size of 23.8 mm × 3.5 mm × 0.94 mm. Experiments show that the TCDA can support a minimum realized gain of 9.51 dB and 9.07 dB for pol-x and pol-y, respectively, within 5 G mmW bands. To verify the design concept, TCDA is fabricated and measured, which achieves 60° scanning without grating lobes. The measurement results demonstrate that the proposed antenna is well suited for future 5 G mmW mobile phones. [ABSTRACT FROM AUTHOR]

Abstract Contemporary analyses of insect population trends are based, for the most part, on a large body of heterogeneous and short‐term datasets of diurnal species that are representative of limited spatial domains. This makes monitoring changes in insect biomass and biodiversity difficult. What is needed is a method for monitoring that provides a consistent, high‐resolution picture of insect populations through time over large areas during day and night. Here, we explore the use of X‐band weather surveillance radar (WSR) for the study of local insect populations using a high‐quality, multi‐week time series of nocturnal moth light trapping data. Specifically, we test the hypotheses that (i) unsupervised data‐driven classification algorithms can differentiate meteorological and biological phenomena, (ii) the diversity of the classes of bioscatterers are quantitatively related to the diversity of insects as measured on the ground and (iii) insect abundance measured at ground level can be predicted quantitatively based on dual‐polarization Doppler WSR variables. Adapting the quasi‐vertical profile analysis method and data clustering techniques developed for the analysis of hydrometeors, we demonstrate that our bioscatterer classification algorithm successfully differentiates bioscatterers from hydrometeors over a large spatial scale and at high temporal resolutions. Furthermore, our results also show a clear relationship between biological and meteorological scatterers and a link between the abundance and diversity of radar‐based bioscatterer clusters and that of nocturnal aerial insects. Thus, we demonstrate the potential utility of this approach for landscape scale monitoring of biodiversity.

This paper presents a novel coupled-fed broadband dual-polarized magnetoelectric dipole antenna for wireless local area network (WLAN) and 5G communication applications. The proposed magnetoelectric dipole antenna is composed of a planar electric dipole and shorting pins as a magnetic dipole to obtain a broad operation frequency band. Two coupled microstrip lines perpendicular to each other are coupled through a cross-shaped slot to excite the vertical and horizontal polarizations. The proposed antenna features a simple structure, high gain, and high polarization isolation. The measured impedance bandwidth of the proposed antenna is 1.8–4.2 GHz (fractional bandwidth of 80%). The measured realized antenna gain value is 3.7–8.5 dBi, and polarization isolation level is 25 dB at the operation frequency band.