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Summary A wearable dual‐band dual‐polarized fabric antenna is screen printed on a cotton polyester substrate to operate at the industrial scientific and medical band at 2.45 GHz and wireless local area network at 5.2 GHz. A rectangular slot with a pair of L‐shaped branches are used to excite dual bands. The rectangular slot is used to achieve lower band resonance at 2.45 GHz with linear polarization, and an L‐shaped branch with a stub is used to obtain the circular polarization at 5.2 GHz. A 3 × 3 electromagnetic bandgap (EBG) structure is enabled behind the antenna to minimize the back radiation and specific absorption rate (SAR). The antenna provides a measured impedance bandwidth (BW) of 25% from 2.1 to 2.7 GHz (600 MHz), and 18% from 4.5 to 5.7 GHz (1.2 GHz), respectively. The antenna also has a 3‐dB axial ratio BW of 15% from 4.6 to 5.35 GHz (750 MHz). The antenna exhibits a measured gain of 5.1 dB at 5.2 GHz and 6.4 dB at 2.45 GHz. The SAR is validated by using a CST (computer simulation technology) voxel human body model and found to be 0.0949 and 0.127 W/kg for 1 g tissue at 5.2 and 2.45 GHz, respectively. The dimension of the proposed EBG integrated antenna is (0.52 λ × 0.52 λ × 0.07 λ). The antenna and EBG structure are screen printed with silver conductive ink, which provides good conductivity, conformability, comfort, wearability, and being lightweight. [ABSTRACT FROM AUTHOR]

This paper presents a novel wideband dual‐polarized air‐patch antenna with enhanced port isolation. The proposed design consists of a suspended metal patch, two feeding slots, and novel composite decoupling structures (CDS). The CDS is composed of two reactive loads (RLs), an additional square slot (ASS), and two neutralizing lines (NLs). The reactive loads and one NL are connected to the feeding slots. The other NL is connected to the ASS. The CDS plays a critical role in achieving wideband high port isolation. The decoupling principles are illustrated by using a circuit model and through rigorous mathematical derivation. Design evolution of the proposed antenna (Ant 1–5) was carefully explained. Experimental results demonstrate that the proposed antenna has a −15 dB refection coefficient bandwidth covering the frequency range of 3.32–3.67 GHz. Additionally, it exhibits high port isolation (>35 dB), low cross polarization, high gain, and excellent total efficiency (>85%). [ABSTRACT FROM AUTHOR]

To address the challenge of balancing load-bearing and electromagnetic (EM) wave absorption properties in aircraft composite skin, the outstanding mechanical and electrical characteristics of carbon fiber (CF) prepregs were utilized to construct a carbon fiber dual-polarized absorbing laminated structure (CFDALS). The bidirectional CF arrays were introduced into the glass fiber (GF) laminated structure, to endow the laminated structure with dual-polarized EM wave absorption performances. Additionally, the excellent load-bearing capacity of the CF reflector was used to enhance the mechanical properties. Simulation results indicate that, the CFDALS achieves an average absorptivity over 90% within the 8~18 GHz frequency band at incident angles of 0°~45°, and within the 5~18 GHz band at incident angles of 0°~60° for TE and TM polarized EM waves, respectively. The 3-point bending simulation results show that, the CFDALS exhibits higher specific flexural strengths and stiffnesses along 2 directions of the CF arrays while achieving dual-polarized EM wave absorption. Incorporation of bidirectionally arranged CF prepregs into GF prepregs enhances the dual-polarized EM wave absorption performance and the bidirectional flexural performance of the CFDALS simultaneously. The work provides a novel solution for the EM wave absorbing and load-bearing integrated design for aircraft composite skin applications. [ABSTRACT FROM AUTHOR]

Based on the shortcomings of the current ultra wide band (UWB) array antenna research and the engineering requirements, a tightly-coupled UWB array antenna is designed. The antenna uses a tightly-coupled dipole array (TCDA) as the antenna radiator and is fed by Marchand Balun with gradual impedance. It has the characteristics of dual polarization, low profile and high gain. The antenna also uses a double-layer frequency selective surface (FSS) and a cross-shaped resistive absorbing material to improve the wide-angle scanning performance, especially the self-excited oscillation caused by the short circuit zero points at high frequency. Through the simulation analysis of the antenna by HFSS, it is concluded that the array has VSWR < 3 in the range of 2-18 GHz. The VSWR is less than 3.5 in the range of 40° angle scanning on the H plane and the VSWR is less than 3.3 in the range of 85° scanning on the E plane, which has excellent E plane scanning capability. The profile of antenna array is 15mm (0.1 llow), the polarization isolation is better than - 25dB, and the gain of 20x20 antenna array exceeds 20 dB,which can be used in airborne radar, spaceborne radar and other application scenarios. [ABSTRACT FROM AUTHOR]

This paper presents the development of a four-port dual-band dual-polarized antenna for transmitting/receiving (Tx/Rx) applications in Ku-band satellite communications. The antenna consists of two antenna elements sharing a common radiating aperture, a low-band element formed by an L-probe proximity-fed square-ring radiator for operation at the Rx band of 10.7–12.75 GHz, and a high-band element realized by a stacked-patch radiator for operation at the Tx band of 13.75–14.5 GHz. Within a compact multilayer structure, the antenna achieves wide dual-band operation, with each band having the ability to simultaneously operate with dual polarization. An antenna prototype is fabricated and tested to verify its performance. The experimental results show that the proposed antenna achieves an impedance bandwidth of 9.28–12.96 GHz (13.21–15.32 GHz), an isolation value between two orthogonal polarizations of 12 dB (12.4 dB), and a peak gain of 6.63 dBi (5.42 diBi) at the low band (high band). Tx/Rx isolation of more than 14 dB is achieved in both the Rx band and Tx band. [ABSTRACT FROM AUTHOR]

A dual-polarized (DP) wideband parabolic reflector antenna with high aperture efficiency and low sidelobe level is proposed for L/S-band vehicular satellite communications. Initially, a pair of cross-arranged dipoles with etching slots and parasitic branches are utilized to achieve wideband characteristic. Subsequently, a top-loaded parasitic beautified substrate, featuring four pairs of rectangular rings arranged around a flower-shaped radiation patch, is employed to prevent the radiation pattern from splitting into two pieces. Finally, by integrating with a parabolic reflector etched with wind-resistance-reduction holes, a parabolic reflector antenna with sidelobe level suppression and stable high aperture efficiency is constructed. Throughout the design process, the principles of wideband operation and low sidelobe levels are analyzed. Measured results exhibit good electrical performance, including a wide bandwidth of 78.57% (1.7-3.9 GHz), a high gain of $21.75\pm 2.25$ dBi, a peak aperture efficiency of up to 73%, a high isolation level of better than 20 dB, and a low sidelobe level of less than −22 dB. These characteristics make the proposed antenna suitable for wideband and anti-interference vehicular satellite communications.

This paper presents a dual-polarized, multi-wideband ceiling antenna with an eight-diagram shape for indoor communication in the 2G/3G/LTE/5G sub-6 GHz frequency range. The horizontally polarized (HP) antenna element consists of an upper frequency eight-diagram shaped radiation element and a lower frequency ring-shaped dipole radiation array, both are printed on one side of a printed-circuit-board (PCB). These elements are fed by a pair of different 1-to-4 power divider (PD) networks on the other side of the PCB. The HP antenna elements are connected by a wideband diplexer and fixed by four nylon columns, ensuring wide bandwidth and good isolation. Additionally, the vertically-polarized (VP) antenna element is positioned at the center of the lower-frequency HP dipole radiation array and consists of two orthogonal conical patches with an open groove. This configuration allows for wide frequency bandwidth, high gain, and aesthetic characteristics. Measurement results demonstrate a wide impedance bandwidth of 114.3% (1.5-5.5 GHz) in the VP direction, as well as two bandwidths of 78.6% (1.66-3.81 GHz) and 8.5% (4.75-5.17 GHz) in the HP direction for the 2G/3G/LTE/5G sub-6 GHz bands. The corresponding peak gains vary within 1.06-6.09 dBi and 3.65-4.95 dBi, respectively. Furthermore, the port isolation level between the HP and VP elements reaches 25 dB, demonstrating satisfactory performance for practical ceiling applications.

A novel wireless local area network (WLAN) antenna with dual-polarized and beam-reconfigurable ability is developed for WLAN 2.4 GHz band application. The antenna is composed of a horizontally polarized (HP) antenna and a vertically polarized (VP) antenna. The radiation pattern of the HP antenna can be switched between an omnidirectional beam and four directional beams in the azimuth plane, while the VP antenna can generate an omnidirectional beam and eight directional beams. Then the antenna prototype is fabricated and measured. The directional beam gain of the HP antenna varies from 2.7 to 3 dBi, and that of the VP antenna varies from 2.5 to 3.5 dBi. The maximum difference between the measured and simulated directional beams is 0.9 dBi. The measured and simulated reflection coefficients of the antenna are below −10 dB for all the beam states, and the isolation between the two polarizations is less than −18 dB in the WLAN 2.4 GHz band. The measured results agree well with the simulated ones, showing a good application prospect in WLAN system in the future.

Two broadband dual-polarized band-notched crossed dipole antennas based on the grounded coplanar waveguide (GCPW) filter for 2G/3G/4G/5G base station are proposed in this paper. Two antennas with two and three radiation nulls are displayed to demonstrate the design innovation. Firstly, a wideband crossed dipole antenna with GCPW feed structure is designed, and its coverage frequency is 1.7-3.6 GHz. Then, a compact GCPW second-order hybrid bandstop filter is designed using defected ground structure (DGS) and defected microstrip structure (DMS). The DGS-DMS filter are embedded inside the antenna radiator to achieve the stopband covering 2.9-3.1 GHz with only one dielectric substrate. At last, a miniaturized GCPW third-order DGS-DMS highly selective bandstop filter is integrated in wideband antenna to realize the stopband of 2.87-3.17 GHz. The proposed band-notched antenna uses only one substrate. Compared with the antenna using second-order filter, the antenna using third-order filter has one more radiation null, wider stopband of 2.87-3.17 GHz and higher selectivity.

This article presents an optimized dual-polarized transmitarray antenna (TA) designed for MIMO applications at the Ka-band, capable of switching beams in two directions. The antenna aperture uses a small unit cell with three layers of Taconic RF-35 dielectric substrates, which can be easily fabricated using PCB technology. The unit cell achieved a 360-degree phase shift and a transmission magnitude exceeding–0.4 dB at 28 GHz. We used nine dual-polarized patch antennas in a cross shape, each with a 10.5 dBi gain at 28 GHz, to switch the beams in two directions without changing the feed location. We optimized the phase distribution in the TA aperture and adjusted the feed antenna’s $F/D$ and tilt to achieve a high-gain antenna with low-gain roll-off during beam switching. The fabricated TA exhibited excellent agreement with the full-wave simulation results. It achieved ±15 degrees and ±30 degrees beam tilts in the x- and y- directions, with less than 0.8 dB gain roll-off for both polarizations.

A dual-polarized dielectric waveguide transmission system is proposed using low-loss material cyclic olefin copolymer (COC), with some other key components such as substrate integrated waveguide (SIW)-based orthomode transducers (OMT), the transitions between the OMT and dielectric waveguide, and the adaptors between the OMT and the standard rectangular waveguide. In the frequency range from 90 to 100 GHz, the proposed whole transmission system with a 40-cm-length COC-based dielectric waveguide has the lowest insertion loss of 5.31 dB caused by the coupling structure loss of 3.17 dB, the straight/bending COC-based dielectric waveguide losses of 2.33/2.47 dB/m, and the unavoidable radiation loss from the transition. The proposed system using COC-based dielectric waveguides could be a promising choice in low-loss and high-capacity off-chip short-to-medium wired transmission. [ABSTRACT FROM AUTHOR]

In this letter, a dual-polarized metal Vivaldi phased array antenna composed of independent structural elements is proposed, covering 6–18 GHz. By designing Vivaldi elements with a flexible and complementary structure, arrays of arbitrary shapes and scales can be constructed. The resonance caused by structural discontinuity is critically studied and eliminated to ensure good performance across the entire band. The antenna elements are fed by 50-Ohm SSMP connectors and manufactured from 2A12 aluminum alloy. An array prototype consisting of 8 × 8 dual-polarized metal has been fabricated and tested with active transmit/receive (T/R) modules to demonstrate the design concept. The array exhibits excellent beam-scanning characteristics in both the E-plane and H-plane, within the scanning range without grating lobes, which shows good agreement with the simulated results. The measured gain results are within the range of 15.2 to 24.8 dBi, and the aperture efficiencies are greater than 91% in the entire operating band. The wideband antenna technology involved in this study can effectively help increase the capacity of communication systems and meets the intentions of the Special Issue. [ABSTRACT FROM AUTHOR]

Optically transparent dual‐band frequency‐selective surfaces (FSSs) are promising candidates to address the specific design challenges of the Internet of Things. This paper demonstrates their potential by discussing different configurations of the two single‐layer FSS designs on an innovative optically transparent polyvinyl chloride surface material. First, FSS cells consist of two cross dipoles placed forming angles of ±45∘ $\pm 4{5}^{\circ }$, where each rotated dipole structure parallel to the other. Then, in the second design, each one of the two cells is mirrored to enable polarization control for each band. As a proof‐of‐concept, five prototypes of each design having a unit cell size of 0.43λ0×0.43λ0 $0.43{\lambda }_{0}\times 0.43{\lambda }_{0}$ are fabricated through a combination of cost‐effective printing and shearing. The manufactured prototypes yield more than 93% transparency and robust dual‐band performance. Moreover, more than 20 and 40 dB isolation for lower‐ and upper‐frequency bands are achieved from the fabricated prototypes. High‐transparency, cost‐effectiveness, and robust high performance in terms of suppression make both structures suitable for sub‐6‐GHz fifth generation applications. [ABSTRACT FROM AUTHOR]

Conducting landslide recognition research holds notable practical significance for disaster management. In response to the challenges posed by noise, information redundancy, and geometric distortions in single-orbit SAR imagery during landslide recognition, this study proposes a dual-polarization SAR image landslide recognition approach that combines ascending and descending time-series information while considering polarization channel details to enhance the accuracy of landslide identification. The results demonstrate notable improvements in landslide recognition accuracy using the ascending and descending fusion strategy compared to single-orbit data, with F1 scores increasing by 5.19% and 8.82% in Hokkaido and Papua New Guinea, respectively. Additionally, utilizing time-series imagery in Group 2 as opposed to using only pre- and post-event images in Group 4 leads to F1 score improvements of 6.94% and 9.23% in Hokkaido and Papua New Guinea, respectively, confirming the effectiveness of time-series information in enhancing landslide recognition accuracy. Furthermore, employing dual-polarization strategies in Group 4 relative to single-polarization Groups 5 and 6 results in peak F1 score increases of 7.46% and 12.07% in Hokkaido and Papua New Guinea, respectively, demonstrating the feasibility of dual-polarization strategies. However, due to limitations in Sentinel-1 imagery resolution and terrain complexities, omissions and false alarms may arise near landslide edges. The improvements achieved in this study hold critical implications for landslide disaster assessment and provide valuable insights for further enhancing landslide recognition capabilities. [ABSTRACT FROM AUTHOR]

In this study, we present a novel dual-polarized patch antenna that exhibits high isolation and two in-band transmission zeros (TZs). The design consists of a suspended metal patch, two feeding probes connected to an internal neutralization line (I-NL), and a T-shaped decoupling network (T-DN). The I-NL is responsible for generating the first TZ, and its decoupling principles are explained through an equivalent circuit model. Rigorous design formulas are also derived to aid in the construction of the feeding structure. The T-DN realizes the second TZ, resulting in further improvement of the decoupling bandwidth. Simulation and experimental results show that the proposed antenna has a wide operating bandwidth (2.5–2.7 GHz), high port isolation (>30 dB), and excellent efficiency (>85%). [ABSTRACT FROM AUTHOR]

A novel dual-band, dual-polarized antenna-duplexer scheme is intended to use for WLAN 802.11a and ISM band applications using Substrate Integrated Waveguide (SIW) Technology. The antenna consists of two planar SIW cavities of different dimensions where a smaller sized diamond-shaped cavity is inserted inside the larger rectangular cavity to share the common aperture area. The diamond-ring shaped slots are etched in each cavity for radiation. The larger diamond-ring slot is excited with a microstrip feedline to operate at 5.2 GHz while the smaller slot is excited with a coaxial probe to operate at 5.8 GHz. The antenna produces linear polarization at 5.2 GHz (5.1–5.3 GHz) due to the merging of TE110 and TE120 cavity modes while circular polarization around 5.8 GHz due to orthogonally excited TM100 and TM010 modes (5.68–5.95 GHz). The slots are excited in an orthogonal fashion to maintain a better decoupling between the ports (i.e. –23 dB). The performance of the antenna has been verified in free space as well as in the vicinity of the human body. The antenna offers the gain of 6.2 dBi /6.6 dBi in free space and 5.8 dBi / 6.4 dBi on-body at lower-/ higher frequency-bands, respectively. Also, the specific absorption rate (SAR) is obtained

This paper introduces novel dual-polarized/duplex filtering antennas with a novel filtering feeding network. The feeding network consists of an all-resonator structure, which shares a common dual-mode resonator. This structure facilitates the isolation of two well-isolated channels through the exploitation of the even and odd modes of the dual-mode resonator. By applying balanced excitation to the odd mode and unbalanced excitation to the even mode, the two modes can be separated, creating a hybrid-like feeding structure. Despite the common resonator, the channels exhibit high isolation, and the overall size of the filtering circuit is much smaller than conventional cascaded-resonator designs. To demonstrate the effectiveness of the proposed feeding network, we have designed, fabricated, and measured a dual-polarized and a duplex filtering antenna. The simulated and measured results agree well, showing isolations greater than 34 dB and 38 dB for dual-polarized and duplex cases, respectively. Our proposed antennas are compared with state-of-the-art developments, demonstrating the advantages of compact size, flexible decoupling frequency ratio, and high isolation.

The present study proposes a dual-polarized bandwidth-enhanced filtering specialized dipole antenna design for 5G by employing a wide printed dipole, filtering resonators, a reflector surface, and specially designed balun structures. Such a configuration is commonly deployed in conventional base stations. To increase the antenna impedance and radiation bandwidth, a specifically designed, wide-printed flared dipole antenna structure is used as the main radiator element. Transmission zeros are introduced at both pass band edges to create a filtering response by engaging parasitic elements. The parasitic element for the higher frequency edge of the filtering is placed close to the maximum amount of the induced current on the radiator at the operating frequency, whereas the parasitic element for the lower frequency edge of the filtering is located close to the perpendicularly polarized structure. The antenna aims to create radiation nulls at the impedance bandwidth limits; therefore, the parasitic arcs are used to create surface currents that cancel the broadside radiation at the limits of the impedance bandwidth. The study illustrates a complete analysis of the broadband printed patch antenna having a filtering effect by parametric investigations on the dimensions and resulting physical phenomenon in detail. To demonstrate the approach, a prototype of the antenna is fabricated and measured. According to the measurement results, the antenna performs 76% impedance bandwidth between 2.49 GHz and 5.59 GHz with $|S_{11}|$ and $|S_{22}| < -10$ dB by providing exceptional isolation values of $|S_{21}| < -20$ dB in entire operating band. The fabricated antenna has a stable radiation beamwidth with less than $\pm 5^{0}$ variation and the measured gain in the operating frequency is almost constant and equal to 8.2 dBi.

In this paper, a dual-polarized broadband high gain base station antenna unit is proposed. The antenna unit comprises an octagonal radiation structure and a pair of orthogonal $\Gamma $ -shaped feeding structure, stacked patch and metal reflection structure. The octagonal radiation structure can effectively increase the radiation area, and the wide working frequency band can be realized by means of coupling and slotting. At the same time, high isolation and stable radiation pattern characteristics can be obtained. The simulation results show that the impedance bandwidth of the antenna is 47% (1.67 - 2.69 GHz) when the reflection coefficient is less than - 20 dB, and the port isolation is greater than 27 dB, a high gain of 10 ± 0.5 dBi can be obtained in the passband. Furthermore, the antenna also obtains a wide half power beam width (HPBW). The HPBW fed through a single port and two ports are around 60°. Finally, the antenna unit is applied to the $4\times11$ antenna array to realize the multi-band dual polarization system.

A low-profile broadband dual-polarized antenna is investigated for base station applications. It consists of two orthogonal dipoles, fork-shaped feeding lines, an artificial magnetic conductor (AMC), and parasitic strips. By utilizing the Brillouin dispersion diagram, the AMC is designed as the antenna reflector. It has a wide in-phase reflection bandwidth of 54.7% (1.54–2.70 GHz) and a surface-wave bound range of 0–2.65 GHz. This design effectively reduces the antenna profile by over 50% compared to traditional antennas without an AMC. For demonstration, a prototype is fabricated for 2G/3G/LTE base station applications. Good agreement between the simulations and measurements is observed. The measured −10-dB impedance bandwidth of our antenna is 55.4% (1.58–2.79 GHz), with a stable gain of 9.5 dBi and a high isolation of more than 30 dB across the impedance passband. As a result, this antenna is an excellent candidate for miniaturized base station antenna applications. [ABSTRACT FROM AUTHOR]

A fixed-frequency beam-scanning leaky-wave antenna (LWA) array with three switchable dual-polarized beams is proposed and experimentally demonstrated. The proposed LWA array consists of three groups of spoof surface plasmon polaritons (SPPs) LWAs with different modulation period lengths and a control circuit. Each group of SPPs LWAs can independently control the beam steering at a fixed frequency by loading varactor diodes. The proposed antenna can be configured in both multi-beam mode and single-beam mode, where the multi-beam mode with optional two or three dual-polarized beams. The beam width can be flexibly adjusted from narrow to wide by switching between multi-beam and single-beam states. The prototype of the proposed LWA array is fabricated and measured, and both simulation and experimental results show that the antenna can accomplish a fixed frequency beam scanning at an operating frequency of 3.3 to 3.8 GHz with a maximum scanning range of about 35° in multi-beam mode and about 55° in single-beam mode. It could be a promising candidate for application in the space–air–ground integrated network scenario in satellite communication and future 6G communication systems. [ABSTRACT FROM AUTHOR]

In this letter, a cavity‐backed annular slot antenna with a reconfigurable dual‐linear polarization of ∓45° employing two PIN diodes for wireless internet of things (IoT) applications was proposed to address issues such as bulky size, circuit complexity, and structural stability. The front‐to‐back ratio and gain enhancements of the proposed antenna with an overall size of 0.44 λ0 × 0.44 λ0 × 0.17 λ0 at 2.545 GHz were designed and accomplished utilizing a cavity‐backed reflector. The impedance bandwidth based on the 10 dB return loss and the peak gain of the proposed antenna are approximately 18.8% (2.26–2.73 GHz) and 7.42 dBi, respectively. [ABSTRACT FROM AUTHOR]

In this paper, a dual-polarized Huygens unit is proposed, which has a double-layer metallic pattern etched on both sides of one dielectric substrate. Induced magnetism enables the structure to support Huygens' resonance, thus obtaining nearly complete available transmission phase coverage. By optimizing the structural parameters, a better transmission performance can be achieved. When the Huygens metasurface was used for the design of a meta-lens, good radiation performance was exhibited, with a maximum gain of 31.15 dBi at 28 GHz, an aperture efficiency of 42.7% and a 3 dB gain bandwidth of 26.4 GHz to 30 GHz (12.86%). Due to its excellent radiation performance and very simple fabrication, this Huygens meta-lens has important applications in millimeter-wave communication systems. [ABSTRACT FROM AUTHOR]

Herein, we present new design principles for gain enhancement and cross-polarization suppression in dual-polarized cavity-backed antennas and demonstrate the capability in an octagonal cavity-backed open prism antenna (OCROP). In our approach, the gain is enhanced through an optimal flaring procedure and a novel metallic iris is used to control the electromagnetic fields and thereby reduce the cross-polarization. Previously, we investigated a dual-polarized OCROP antenna configuration and were able to simultaneously achieve 50% impedance bandwidth, 40% cross-polarization bandwidth (≤25 dB), and 10.2 dBi peak gain. In this study, we investigated gain enhancement by flaring an upper section of the ground cavity sidewalls, while maintaining a constant cavity height. Two cases were investigated: (1) the flare angle was modified, while the ratio of the non-flared to flared sidewall heights was kept constant, and (2) the ratio of the non-flared to flared sidewall heights was varied. In case 1, we established that, while increasing the flare angle results in a gain increase, there is a limit, as cross-polarization at the upper operating frequencies increases. In case 2, we were able to reduce the aperture phase error and achieve a higher peak gain of 12.8 dBi. To address the increased cross-polarization at the high frequency end when a large flare was used, we added a metallic iris at the junction of non-flared and flared sidewalls. We showed that increasing the iris width generally decreases the cross-polarization at high frequencies, without compromising the gain and impedance bandwidth. At an optimal width, it provides a nearly constant, low cross-polarization (below −25.8 dB) and a peak gain of 13.3 dBi, across the entire 50.7% impedance bandwidth of the antenna. We fabricated and successfully tested a prototype to verify the design and simulation approach. These results prove that incorporating an aperture flare with a metallic iris can significantly improve the gain and cross-polarization performance of cavity-backed antennas. [ABSTRACT FROM AUTHOR]

This work demonstrates a novel, reflective-type, dual-polarized multiband polarization transformer for various C to Ku band applications. The design constitutes a top FSS printed on a thin FR-4 grounded dielectric substrate. A y / x -polarized incident wave experiences linear-circular conversion from 4.61 to 4.71 GHz (right-hand circular polarized (RHCP)/left-hand circular polarized (LHCP)), 5.44 to 7.68 GHz (LHCP/RHCP), 10.13 to 14.98 GHz (RHCP/LHCP), and 16.68 to 17.19 GHz (LHCP/RHCP) with 3.41, 34.15, 38.63, and 3.01% FBW, respectively. In addition, it performs linear-cross conversions with a minimum 90% polarization conversion ratio (PCR) from 4.92 to 5.18 GHz, 8.32 to 9.41 GHz, and 15.56 to 16.25 GHz with 5.15, 12.30, and 4.34% FBW. Multiple surface plasmonic resonances are responsible for these polarization conversions in different bands. The device performance is angular stable for both transverse electric (TE) and transverse magnetic (TM) incidences. The design novelty lies in compacted periodicity 0.112 λL , low-profile thickness 0.037 λL with a multi-conversion (switching the orthogonal circular rotation in consecutive bands), and stable angular response, which can potentially be used in real-time applications. [ABSTRACT FROM AUTHOR]

In this paper, a dual-polarized omnidirectional rectenna array using a hybrid power-combining scheme is proposed for the applications of RF energy harvesting. In the antenna design part, two omnidirectional antenna subarrays are created to receive horizontally polarized electromagnetic (EM) waves and a four-dipole subarray is produced to receive vertically polarized incoming EM waves. The two antenna subarrays of different polarizations are combined and optimized, so as to reduce the mutual influence between them. In this way, a dual-polarized omnidirectional antenna array is realized. In the rectifier design part, a half-wave rectifying structure is adopted for converting the RF energy into DC energy. Based on the Wilkinson power divider and 3-dB hybrid coupler structure, a power-combining network is designed to connect the whole antenna array and rectifiers. The proposed rectenna array is fabricated and measured under different RF energy harvesting scenarios. All simulated and measured results are in good agreement, which verifies the capabilities of the designed rectenna array. [ABSTRACT FROM AUTHOR]

A dual-polarized double-layer microstrip antenna with a metasurface structure is proposed for 5G and 5G Wi-Fi. A total of 4 modified patches are used for the middle layer structure, and 24 square patches are used for the top layer structure. The double-layer design has achieved −10 dB bandwidths of 64.1% (3.13 GHz~6.08 GHz) and 61.1% (3.18 GHz~5.98 GHz). The dual aperture coupling method is adopted, and the measured port isolation is more than 31 dB. A low profile of 0.096λ0 is obtained (λ0 is the wavelength of 4.58 GHz in the air) for a compact design. Broadside radiation patterns have been realized, and the measured peak gains are 11.1 dBi and 11.3 dBi for two polarizations. The antenna structure and E-field distributions are discussed to clarify its working principle. This dual-polarized double-layer antenna can accommodate 5G and 5G Wi-Fi simultaneously, which can be a competitive candidate for 5G communication systems. [ABSTRACT FROM AUTHOR]

A compact three-dimensional (3-D) metal-printed ridged waveguide slot array antenna with wideband, dual linear polarization and low cross-polarization is presented for X-band applications. The proposed design achieves a compact structure due to the method of using a ridged waveguide (RWG). A vertically linear polarized (VP) array is realized through eight longitudinal shunt slots etched on the non-ridged broad wall of the RWG, while a horizontally linear polarized (HP) array is realized through eight V-shaped slots cut on the ridged broad wall of the RWG. To extend the operating bandwidth, each 1 × 8-element linear array is separated into two 1 × 4-element sub-arrays through a central feeding technique. The two sub-arrays of the VP array are excited with equal amplitude and are 180° out-of-phase through a T-junction power divider, which connects the coaxial feed and the radiated waveguide, while the two HP subarrays are directly excited by a coaxial feed with equal amplitude and remain in phase. The feed structure uses coaxial probes directly attached to the RWG to provide good mechanical stability and low voltage around the feed. An optimized 2 × 8-element dual-polarized array is fabricated using 3-D metal-printing technology for experimental verification. The measured −10 dB impedance bandwidth of the VP array is 1.2 GHz (12.2%) and, of the HP array, is 1.1 GHz (11.2%) with maximum gains of 14.6 and 15.5 dBi, respectively. There is good polarization purity over the entire operating bandwidth with a cross-polarization level better than −40 dB in the main beam direction. The isolation between two orthogonal polarized arrays is greater than 40 dB over the whole band. [ABSTRACT FROM AUTHOR]

A novel double-layer Huygens’ unit with dual-polarized response and complete phase coverage has been proposed for highly efficient meta-lens antenna application. The designed unit is a symmetric structure in which the double-layer metallic patterns not only act as the electric dipoles but also induce the magnetic dipoles. The balance between the initial electric dipole and the induced magnetic dipole makes the impedance of the metasurface match with that of free space, thus allowing efficient transmission of electromagnetic waves. Moreover, full transmission phase shift and near-unit transmission amplitude can be achieved simultaneously by change the structural parameters of the unit. Utilizing such electromagnetic properties, a dual-polarized meta-lens consisting of 35 × 35 units with size of 161 × 161 mm2 is designed, fabricated and measured. The results exhibit its good radiation performance. The maximum gain at a frequency of 28 GHz reaches 30.8 dBi, with an aperture efficiency of 42.3%. The 3-dB gain bandwidth reaches 12.5%, covering the frequency range of 26.7–30.2 GHz. The simple structure of the designed dual-polarized metasurface, high gain and high antenna efficiency make it an important antenna engineering role.

This paper presents a single-layer dual-polarized filtering antenna with good out-of-band suppression. By using inherent characteristic of the patch’s eigenmode and meanwhile merging four filtering strategies, i.e., parasitic patches, slot on the driving patch, and defected ground structure (DGS), a low-profile filtering antenna design with five radiation nulls has been realized. With the designed filtering antenna, a conventional 1×2 array with a spacing of 0.91λ is first developed. In order to reduce the sidelobe level of the array, a sharing patching scheme is introduced to decrease the interspace between the elements as 0.44λ, with the same physical size as the conventional array. In addition, a concept to measure total isolation between two kinds of the polarized ports in the array, i.e., SddVH, has been derived for the first time. The prototype of the proposed array is fabricated with a profile of 0.038λ. Measured results indicate that the designed novel array has an operational band of 3.53–4.06 GHz, SddVH better than 41 dB, a sidelobe level below −18 dB, and a suppression level above 20 dB with the stopband up to 0.5 GHz and 5 GHz.

This paper presents the development of a four-port dual-band dual-polarized antenna for transmitting/receiving (Tx/Rx) applications in Ku-band satellite communications. The antenna consists of two antenna elements sharing a common radiating aperture, a low-band element formed by an L-probe proximity-fed square-ring radiator for operation at the Rx band of 10.7–12.75 GHz, and a high-band element realized by a stacked-patch radiator for operation at the Tx band of 13.75–14.5 GHz. Within a compact multilayer structure, the antenna achieves wide dual-band operation, with each band having the ability to simultaneously operate with dual polarization. An antenna prototype is fabricated and tested to verify its performance. The experimental results show that the proposed antenna achieves an impedance bandwidth of 9.28–12.96 GHz (13.21–15.32 GHz), an isolation value between two orthogonal polarizations of 12 dB (12.4 dB), and a peak gain of 6.63 dBi (5.42 diBi) at the low band (high band). Tx/Rx isolation of more than 14 dB is achieved in both the Rx band and Tx band.

In this letter, a dual-polarized metal Vivaldi phased array antenna composed of independent structural elements is proposed, covering 6–18 GHz. By designing Vivaldi elements with a flexible and complementary structure, arrays of arbitrary shapes and scales can be constructed. The resonance caused by structural discontinuity is critically studied and eliminated to ensure good performance across the entire band. The antenna elements are fed by 50-Ohm SSMP connectors and manufactured from 2A12 aluminum alloy. An array prototype consisting of 8 × 8 dual-polarized metal has been fabricated and tested with active transmit/receive (T/R) modules to demonstrate the design concept. The array exhibits excellent beam-scanning characteristics in both the E-plane and H-plane, within the scanning range without grating lobes, which shows good agreement with the simulated results. The measured gain results are within the range of 15.2 to 24.8 dBi, and the aperture efficiencies are greater than 91% in the entire operating band. The wideband antenna technology involved in this study can effectively help increase the capacity of communication systems and meets the intentions of the Special Issue.

This study presents a novel dual-polarized magnetoelectric dipole antenna and its array with director and rectangular parasitic metal patches for LTE and 5G sub-6 GHz base station applications. This antenna is composed of L-shaped magnetic dipoles, planar electric dipoles, rectangular director, rectangular parasitic metal patches, and η-shaped feed probes. The gain and bandwidth were enhanced by using the director and parasitic metal patches. The measured impedance bandwidth of the antenna was 82.8% (1.62–3.91 GHz, VSWR < 1.5), and its gain was 10 ± 0.5 dBi. The profile of the antenna unit, operated at 1.7 GHz, was only 42 mm (0.227λ0, where λ0 represents the free space wavelength corresponding to the lowest resonance frequency point). Subsequently, four antenna units were arranged in a line array with 0.6λ0 spacing. Both the antenna and its array were fabricated and measured. The measurement results show that the array has good radiation characteristics, such as broad bandwidth covering 1.65–3.97 GHz (VSWR < 1.5), high gain (its gain was great than 15.2 dBi), and high radiation efficiency (>90%). Its HPBWs were 63° ± 4° and 15° ± 2° for H- and E-planes, respectively. The design can cover TD-LTE and 5G sub-6 GHz NR n78 frequency bands very well, meaning that this is a good candidate antenna for base station applications. [ABSTRACT FROM AUTHOR]

A novel dual-band, dual-polarized antenna-duplexer scheme is intended to use for WLAN 802.11a and ISM band applications using Substrate Integrated Waveguide (SIW) Technology. The antenna consists of two planar SIW cavities of different dimensions where a smaller sized diamond-shaped cavity is inserted inside the larger rectangular cavity to share the common aperture area. The diamond-ring shaped slots are etched in each cavity for radiation. The larger diamond-ring slot is excited with a microstrip feedline to operate at 5.2 GHz while the smaller slot is excited with a coaxial probe to operate at 5.8 GHz. The antenna produces linear polarization at 5.2 GHz (5.1–5.3 GHz) due to the merging of TE 110 and TE 120 cavity modes while circular polarization around 5.8 GHz due to orthogonally excited TM 100 and TM 010 modes (5.68–5.95 GHz). The slots are excited in an orthogonal fashion to maintain a better decoupling between the ports (i.e. –23 dB). The performance of the antenna has been verified in free space as well as in the vicinity of the human body. The antenna offers the gain of 6.2 dBi /6.6 dBi in free space and 5.8 dBi / 6.4 dBi on-body at lower-/ higher frequency-bands, respectively. Also, the specific absorption rate (SAR) is obtained<0.245 W/Kg for 0.5 W input power averaged over 10 mW/g mass of the tissue. The proposed design is a low-profile, compact single-layered design, which is a suitable option for off-body communication. [ABSTRACT FROM AUTHOR]

The generalized Kerker effects have attracted increasing interests in recent years due to their abilities to manipulate the far-field properties of metasurfaces. However, the dual-polarized generalized Kerker effect enabling different tailoring of orthogonally-polarized electromagnetic waves has not yet been reported. Herein, we demonstrate polarization-controlled dual resonant lattice Kerker effects in periodic silicon nanodisks. By varying the incident angle, the electric dipole and magnetic dipole surface lattice resonances can spectrally overlap, causing zero reflectance and unitary transmittance, i.e., the resonant lattice Kerker effect. The incident angle for achieving this effect can be tuned differently for s- and p-polarizations over large regions by varying the nanodisk size or the lattice periods. The proposed dual-polarized resonant lattice Kerker effects open up avenues for polarization-controlled manipulation of the phase and wavefront of light with metasurfaces. [ABSTRACT FROM AUTHOR]

A non-resonant metasurface (NRMS) concept is reported in this paper to improve the isolation of dual-polarized and wideband large-scale antenna arrays. By properly designing the NRMS, it can perform stable negative permeability and positive permittivity along the tangential direction of the NRMS within a wide band, which can be fully employed to suppress the mutual couplings of large-scale antenna arrays. At the same time, the proposed NRMS can also result in positive permittivity and permeability along the normal direction of the NRMS, which guarantees the free propagation of electromagnetic waves from antenna arrays along the normal direction. For demonstration, a 4×4 dual-polarized antenna array loading with the proposed NRMS is designed to improve the isolations of the antenna array. The simulations demonstrate that the isolations among all ports are over 24 dB from 4.36 to 4.94 GHz, which are experimentally verified by the measured results. Moreover, the radiation patterns of antenna elements are still maintained after leveraging the proposed NRMS. Due to the simple structure of the proposed NRMS, it is very promising to be widely employed for massive MIMO antenna arrays. [ABSTRACT FROM AUTHOR]

Conducting landslide recognition research holds notable practical significance for disaster management. In response to the challenges posed by noise, information redundancy, and geometric distortions in single-orbit SAR imagery during landslide recognition, this study proposes a dual-polarization SAR image landslide recognition approach that combines ascending and descending time-series information while considering polarization channel details to enhance the accuracy of landslide identification. The results demonstrate notable improvements in landslide recognition accuracy using the ascending and descending fusion strategy compared to single-orbit data, with F1 scores increasing by 5.19% and 8.82% in Hokkaido and Papua New Guinea, respectively. Additionally, utilizing time-series imagery in Group 2 as opposed to using only pre- and post-event images in Group 4 leads to F1 score improvements of 6.94% and 9.23% in Hokkaido and Papua New Guinea, respectively, confirming the effectiveness of time-series information in enhancing landslide recognition accuracy. Furthermore, employing dual-polarization strategies in Group 4 relative to single-polarization Groups 5 and 6 results in peak F1 score increases of 7.46% and 12.07% in Hokkaido and Papua New Guinea, respectively, demonstrating the feasibility of dual-polarization strategies. However, due to limitations in Sentinel-1 imagery resolution and terrain complexities, omissions and false alarms may arise near landslide edges. The improvements achieved in this study hold critical implications for landslide disaster assessment and provide valuable insights for further enhancing landslide recognition capabilities.

Substrate Integrated Waveguide Cavity Backed Slot Antennas (SIW CBSA) are emerging candidates for planar Integrated Circuit (IC) technology in Millimetre-wave (MMW) bands. This peculiar antenna holds the advantage of conventional metallic cavity-backed antennas, with high gain, high front-to-back ratio, and low cross-polarization level. SIW CBSA structures are the best option for planar integration with a low profile and low fabrication cost in the design of MMW systems. This paper discusses various forms of SIW CBSA structures, their operating mechanism, and methods of improving their performance in terms of gain, bandwidth, size reduction, beamforming capability, and multiple bands of operation. From this discussion, we can select the antenna with the required characteristics of gain, dual-band, and dual-polarization suited for present and future-generation applications.

The development of an ambient radio frequency (RF) powered Internet of Things (IoT) wireless sensor system is reported. The system integrates all major components including multiple antennas, rectifiers, a power management unit (PMU), a microcontroller unit (MCU) with RF transceiver module and sensing unit. A novelty of this applied engineering innovation is the design and use of multi-band dual-polarized multiple antennas to handle the low ambient RF power density found in the everyday environment. Our prototype demonstrates that it is possible to sense temperature, pressure and humidity and wirelessly transmit these signals to a central server with a duty cycle of approximately 15 minutes, when the background ambient RF signals are as low as −28.6 dBm at 950 MHz. The proposed system can address the important issue of energy supply in the development of IoT providing an alternative energy source to batteries or solar cells. Ambient RF powered IoT devices do not require periodic replacement of their batteries or to be placed in visible regions which makes them suitable for wall, ceiling and floor applications. Our ambient RF powered IoT wireless sensor system provides concrete proof, through demonstration, that harnessing ambient RF energy for powering IoT sensor systems is feasible.

A wearable dual-port button antenna that excites pattern-diversity dual-polarized waves is proposed for on-/off-body applications. Its simple structure comprises of two radiators and a common ground plane designed into two substrates. The crossed-dipole radiator is made by two symmetric bowtie dipoles printed on a circular-shaped semi-rigid substrate, which covers an ultra-wideband (UWB) application with circular polarization and directional radiation patterns, high gain, and high efficiency suitable for off-body communication. The annular-ring radiator and common ground plane are made by a conductive textile on the square-shaped flexible-felt substrate. The annular-ring radiator is shorted to the ground plane using four vias, which generates triple TM modes covering the 2.45/5.85 GHz wireless body area networks (WBAN) with omni-directional radiation patterns and a 3.8 GHz C-band with a directional radiation pattern suitable for on-/off-body communications. The fabricated antenna is verified by measurement in both free space and phantom body environment. Measurements agreed well with simulations. Simulated specific absorption rates (SARs) under US and EU standards are below the safe level, making the proposed antenna suitable for on-/off-body communications.

The high isolation massive antenna arrays are the key devices in the base station of the future wireless communication systems. The challenge for the array application is how to reduce the coupling among the array elements. This paper introduces a new decoupling method for massive MIMO arrays with an inner-element distance of around half wavelength by using a triple-layer metasurface (TMS). The TMS comprises three identical surfaces. The waves reflected from the bottom metasurface (MS) and top two-layer MS have the same amplitudes and the opposite phases, which are canceled with each other. An example of $4\times 4$ dual-polarized wideband microstrip array with a TMS is proposed to verify the decoupling method. The simulation and measurement show that the TMS can help reduce the coupling among the array elements to less than −24 dB in both the co-polarization and cross-polarization directions within 4.23-4.82 GHz. In the meanwhile, the radiation characteristics of the arrays with and without TMS are almost unchanged.

A compact wideband dual-polarized antenna for base station application is proposed. The antenna element consists of a main radiator, two baluns, and a reflector. Two methods are used to enhance bandwidth and improve the port-to-port isolation. Firstly, by integrating the parasitic elements to traditional dipoles, new resonant modes are introduced to realize broadband, which can be controlled flexibly. Subsequently, part of the parasitic elements is removed to form asymmetric dipoles. Due to the asymmetry construction of the design, the polarization isolation of the antenna achieves more than 30 dB in the whole working band with stable radiation patterns. In addition, the specially designed parasitic elements achieve enhanced bandwidth without increasing the size of the radiator. The Simulation and measurement results show that the antenna has an impedance bandwidth of 32.7% (690-960 MHz). Moreover, a stable half-power beamwidth (HPBW) of 68°±5° and a high gain of 8.5±0.3 dBi is achieved. To verify the performance of the antenna, a compact high-gain base station array was designed and manufactured. The good performance of the proposed antenna makes it a promising candidate for 4G/5G base station application.

In this paper, a novel compact, dual-polarized, dual-broadband shared-aperture antenna array unit consisting of one lower-band (LB) element and four upper-band (UB) elements underneath is proposed for 5G mobile communications. L-shaped parasitic branches are introduced in the LB to broaden the bandwidth while reducing the mutual coupling between the LB element and UB elements. Compared with the traditional lower-band dipole, the proposed LB element has far less influence on the electric field of the UB array, thus preserving their radiation patterns. To verify its performance, the antenna array unit is fabricated and experimentally demonstrated to achieve the bandwidth of 32.7% (0.69–0.96 GHz) in the LB and 45.5% (1.7–2.7 GHz) in the UB with a voltage standing wave ratio (VSWR) of lower than 1.5. High port isolation and stable radiation patterns are attained in both the LB and UB as required for dual-band base station antennas.

A broadband radiation dual‐polarized antenna is proposed for the application of 5G sub‐6 GHz base stations. The radiator of the antenna is consisted of a pair of crisscrossed sector dipoles, and is fed by microstrip stubs. By etching rectangular slots on the patches, the resonant modes of the antenna can increase to eight. Therefore, the broadband characteristic can be realized by effectively exciting the ideal modes. And the dual‐polarized characteristic is also achieved by exciting the ideal modes. The overall size of the proposed antenna is λ×λ×0.258λ (λ is the free‐space wavelength at 4.3 GHz) and it is fabricated and tested. The measured bandwidth can achieve 47.2% (3.19 ~ 5.22 GHz) for S11 <−10 dB and S21 < −26 dB, and the half‐power beam width (HPBW) is 55 ± 6° within the working band. The antenna gain attains 8.3 ± 1.6 dBi with a good stable radiation pattern. These features make the antenna more attractive for 5G sub‐6 GHz communication applications. [ABSTRACT FROM AUTHOR]

A broadband dual‐polarized magnetoelectric (ME) dipole filtering antenna is investigated in this letter. The antenna is composed of radiation patches, vertical shorting patches, feed microstrip lines and a ground plane. By properly changing the length of the feeding microstrip line, a radiation null is generated at upper passband edge. On the other hand, by nesting a parasitic patch inside the radiation patch, another radiation null is introduced into the upper passband edge successfully. The utilization of the inherent lower passband edge radiation null of ME‐dipole and the introduction of the aforementioned two radiation nulls make the antenna obtain a good filtering response. For verification, a prototype is designed, fabricated, and relevant measurements are obtained, which agree well with the simulated ones. The measured results show that the antenna achieves a relative bandwidth of 71.4% (2.7–5.7 GHz) and the out of band rejection level is higher than 13.36 dB. Moreover, the antenna has a peak‐realized gain of 8.43 dBi and stable radiation patterns are obtained in the whole passband. [ABSTRACT FROM AUTHOR]

A compacted dual‐polarized base station antenna with filtering characteristics and enhanced broadband is proposed for sub‐6 GHz applications in this letter. The lower stopband radiation null is thus generated by the parasitic loops on the back of the substrate. In order to achieve the filtering response and extend the bandwidth of at the upper edge of the passband, a split strip‐type dipole arm is added to the inner part of the annular dipole to form the radiation null. On the flip side, by changing the shape of the Balun ground, another filtering null is generated at the upper‐band to suppress the second harmonic, achieving better broadband suppression performance. The experimental results show that the antenna has a 42.9% (3.3–5.1 GHz) impedance bandwidth, and the in‐band average gain reaches 8.3 dBi, while the out‐of‐band gain suppression is greater than 17 dB. [ABSTRACT FROM AUTHOR]

This paper demonstrates a broadband dual‐polarized metasurface antenna with high isolation and low cross‐polarization using characteristic mode analysis. A wideband metasurface with stable radiation pattern is presented by splitting the edge patches into 2 × 2 sub‐array and introducing Minkowski fractal structure in the corner patches. To achieve the dual‐polarized operation, a pair of degenerate modes of the metasurface are selected, and thus high isolation and low cross‐polarization are obtained. The metasurface is excited by two slot antennas placed orthogonally. A prototype with an overall size of 1.46 λ0 × 1.46 λ0 × 0.07 λ0 (λ0 is the free‐space wavelength at center frequency) is fabricated. The proposed antenna could achieve dual‐polarization operation. The experiment results show that the −10 dB impedance bandwidths for each port are 28.9% (4.74–6.34 GHz) and 31.4% (4.62–6.34 GHz), respectively. The isolation between the two ports is higher than 31.8 dB, and cross‐polarization level is better than −28 dB. Moreover, broadside radiation performances for two ports are obtained. [ABSTRACT FROM AUTHOR]

A dual-band, dual-polarized filtering antenna with a cross-shaped dielectric strip resonator is proposed. The dual-band filtering radiation function is achieved by utilizing the odd and even modes of the stub loaded microstrip resonator to excite the TMδ1 and TMδ3 mode in each polarization direction of the cross-shaped dielectric strip resonator. The cross-shaped dielectric strip resonator is synthesized by the E-field distributions and the magnitude comparison along different polarization directions, which can ensure the isolation between two polarizations. Compared with dual-band filtering dielectric antennas, the proposed antenna has the characteristic of dual-polarized radiation, as well as a low profile. A prototype is fabricated and measured, which operates at 3.5 GHz and 4.9 GHz with the fractional bandwidths (FBW) of 5.40% and 2.03%, respectively, and the gains of these two bands are 6.4 dBi and 6.2 dBi, respectively. The two radiation nulls are located at 4.4 GHz and 5.1 GHz. Furthermore, the measured isolation between the two ports in the frequency band can achieve 16 dB. [ABSTRACT FROM AUTHOR]