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Abstract This article proposes a dual mode dual-polarized antenna configuration for IRNSS and fifth generation (5G) applications, operating at a frequency of 3.5 GHz based on characteristic mode analysis (CMA), and aims to provide broadband dual-polarized functionality. The original design of the antenna is a traditional patch antenna, and its dual-polarized features are determined using characteristic mode analysis. The full-wave method is used to stimulate both orthogonal modes using a 50 Ω coaxial input line at 3.5 GHz. In this design, the circular patch has been extended into an elliptical patch through a process of mode separation. The circular patch exhibits resonance at a frequency of 2.5 GHz, whereas the extended elliptical radiator demonstrates two resonance modes at 2.5 GHz and 3.5 GHz. The operational mechanism is elucidated by modal analysis and characteristic angle. This antenna operates on two different frequencies at the 2.5 GHz IRNSS band with horizontal polarization and the 3.5 GHz 5G service with vertical polarization. The maximum gain achieved with these frequency ranges is 5.31 dBi and 4.72 dBi, respectively. A ring resonator is chosen to improve the axial ratio and impedance bandwidth of the suggested prototype. The antenna's ground plane is shaped like a rectangle and features a V-shaped slot in the radiating patch. The antenna's physical footprint is 50 mm × 50 mm × 1.6 mm and an FR4 dielectric substrate serves as its foundation. Through its interaction with a PIN diode, the diode modifies the polarization of the antenna. The antenna functions as a right-handed circular polarization (RHCP), when the diode is operational. The bandwidth from 4.3 to 7.5 GHz is covered. On the other hand, it generates linear polarization (LP) between 4.2 and 5.3 GHz. The experimental antenna is evaluated and examined for its performance characteristics. The simulations are carried out utilizing the CST simulator. A prototype antenna has been manufactured and its performance has been validated against simulated findings.

This article proposes a dual mode dual-polarized antenna configuration for IRNSS and fifth generation (5G) applications, operating at a frequency of 3.5 GHz based on characteristic mode analysis (CMA), and aims to provide broadband dual-polarized functionality. The original design of the antenna is a traditional patch antenna, and its dual-polarized features are determined using characteristic mode analysis. The full-wave method is used to stimulate both orthogonal modes using a 50 Ω coaxial input line at 3.5 GHz. In this design, the circular patch has been extended into an elliptical patch through a process of mode separation. The circular patch exhibits resonance at a frequency of 2.5 GHz, whereas the extended elliptical radiator demonstrates two resonance modes at 2.5 GHz and 3.5 GHz. The operational mechanism is elucidated by modal analysis and characteristic angle. This antenna operates on two different frequencies at the 2.5 GHz IRNSS band with horizontal polarization and the 3.5 GHz 5G service with vertical polarization. The maximum gain achieved with these frequency ranges is 5.31 dBi and 4.72 dBi, respectively. A ring resonator is chosen to improve the axial ratio and impedance bandwidth of the suggested prototype. The antenna's ground plane is shaped like a rectangle and features a V-shaped slot in the radiating patch. The antenna's physical footprint is 50 mm × 50 mm × 1.6 mm and an FR4 dielectric substrate serves as its foundation. Through its interaction with a PIN diode, the diode modifies the polarization of the antenna. The antenna functions as a right-handed circular polarization (RHCP), when the diode is operational. The bandwidth from 4.3 to 7.5 GHz is covered. On the other hand, it generates linear polarization (LP) between 4.2 and 5.3 GHz. The experimental antenna is evaluated and examined for its performance characteristics. The simulations are carried out utilizing the CST simulator. A prototype antenna has been manufactured and its performance has been validated against simulated findings. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) Janus structures, as a newly derived form of 2D materials, have recently attracted great attention due to their structural symmetry breaking along with a piezoelectric effect and potential applications in nanoscale sensors, surface acoustic waves, and energy harvesters. To date, 2D Janus materials mainly appear in the IV–VI and III–V systems but are scarce involving the IV–V elements. Hereby, utilizing first-principles structure prediction, a stable IV–V–V family of 2D Janus structure 1T-M2AB (M = Si, Ge, Sn, A/B = N, P, As) was proposed. Their electronic, elastic, and piezoelectric properties are systematically investigated and compared. The calculated piezoelectric coefficient results reveal that the 1T-Sn2NP exhibits superior piezoelectric performance with a high in-plane piezoelectric constant (−8.07 pm/V), beyond many known 2D piezoelectric materials. Three independent factors of charge density distribution, vertical mirror asymmetry, and electrostatic potential gradients were assessed, which can well account for the piezoelectric characteristics of 1T-M2AB. This work not only demonstrates the potential applications of 2D Janus 1T-M2AB monolayer in piezoelectric devices but also enriches the family of 2D Janus structures. [ABSTRACT FROM AUTHOR]

A low profile, vertically polarized, ultra-wideband array antenna with end-fire beams operating in an ultra-high frequency (UHF) band is developed in this paper. The array antenna consists of 1×16 log-periodic top-hat loaded monopole antenna arrays and is feasible to embed into a shallow cavity to further reduce the array height. Capacitance is introduced in the proposed antenna element to reduce profile height and the rectangular top hats are carefully designed to minimize the transverse dimension. Simulated results show that when the antenna array operates in a frequency range of 300 MHz–900 ​MHz, the end-fire radiation pattern achieves ±45° scanning range in the horizontal plane. Then prototypes of the proposed end-fire antenna element and a uniformly spaced linear array (1×2) are fabricated and validated. The end-fire antenna array should be suitable for airborne applications where low profile and conformal scanning phased antenna arrays with end-fire radiations are required. This design is attractive for airborne platform applications that are used to search, discover, identify, and scout the aerial target with vertically polarized beams.

Vertically polarized omnidirectional antenna system (VPOAS) and horizontally polarized omnidirectional antenna system (HPOAS) are designed and theoretically analyzed at 2.2 GHz for NAG-Missile telemetry. Theoretical formulations of far-zone field patterns are derived using the cavity model in conjunction with array theory, equivalence theorem, and image theory. The derived radiation patterns are plotted using MATLAB software. The proposed antenna is simulated using CST software and fabricated to validate the derived results. The proposed antenna systems are resonating at 2.22 GHz with 32 MHz impedance bandwidth and peak gain of 4.15 and 5.37 dBi for VPOAS and HPOAS, respectively. [ABSTRACT FROM AUTHOR]

When a pair of calculable dipole antennas (CalDAs) with a 3-dB hybrid balun is used for a validation test of a constructed open area test site (OATS), the theoretical normalized site attenuation (NSA) curves of an ideal OATS for the CalDAs are required. This paper presents a method to calculate this theoretical NSA in the frequency range of 30 MHz to 1 GHz. The theoretical NSA was directly derived using the power mismatch and dissipative loss concepts of an NSA measurement system. Accurate antenna factors (AFs) above the ground plane were also needed and calculated to obtain the theoretical NSA. When free-space AFs are used to determine the measured NSA, AF correction factors known as mutual impedance correction factors are needed. Both free-space AFs and AF correction factors were also considered.

• First-principles calculations plus Monte Carlo simulations are used to investigate the multiferroicity of α-CrOOH. • α-CrOOH with a robust FE and AFM near room temperature. • a tiny tensile strain can transform α-CrOOH from AFM ground state to FM. • Ti 2 CO 2 /α-CrOOH/ Ti 2 CO 2 H FE FETs can be used for various applications such as high-density NVM. Ferroelectric materials with vertical polarization could provide ground-breaking device applications, compatible with electric-field switching even in the presence of a surface-depolarizing field. Herein, we present theoretical evidence that rhombohedral chromium oxide hydroxide α-CrOOH, which has been synthesized experimentally, is a type-Ⅰ multiferroic. First-principles calculations plus Monte Carlo simulations indicate that α-CrOOH is a room temperature proton transfer ferroelectricity semiconductor with robust electric polarization as large as 24.6 μ C / c m 2. Moreover, the system exhibits an anti-ferromagnetism ground state with a Neel temperature of 340 K, where strain can modulate the transition from antiferromagnetic to ferromagnetic. Finally, a two-dimensional (2D) heterostructure model was designed, composed of monolayer α-CrOOH and functional MXene, for various applications such as non-volatile memory (NVM). The remarkable properties may enable the system to hold great potential for the development of future multifunctional devices. [ABSTRACT FROM AUTHOR]

A magnetic Yagi-Uda antenna applying higher order mode in millimeter-wave (mm-Wave) band with vertically polarized endfire radiation is proposed in this article. Surface wave mode analysis is applied to spot TE mode for magnetic Yagi-Uda antenna in contrast to TM mode for electric Yagi-Uda antenna. A modified structure evolved from conventional U-shaped cavity is used to address the reversed current issue for higher order mode, which exhibits a more uniform phase distribution at the Yagi-Uda array end. Then, a composite end-feeding structure with reflector integrated is further introduced to minimize its parasitic effects for practical antenna design in mm-Wave band. To validate the design, a prototype with a size of 2.7 $\lambda _{\mathbf {0}}\times1.25\lambda _{\mathbf {0}}\times0.088\lambda _{\mathbf {0}}$ is fabricated and tested. It can achieve anendfiregain of 8–11 dBi within 24–26 GHz with –10 dB impedance band covering an even wider frequency range. The measured front-to-back ratio (FBR) is larger than 16.1 dB. Vertically polarized radiation is realized with cross-polarization level lower than –20 dB atendfiredirection. [ABSTRACT FROM AUTHOR]

This article presents a low-profile planar phased array with improved reflection (wideband filtering response) and radiation (wide-angular scan) performance. On one hand, the filtering response with harmonic suppression is integrated into the design of the single-layer array element without extra filtering resonators, such as external filters. As a result, the designed array possesses a reflection bandwidth of 4.6–5.3 GHz and two radiation nulls at either the upper or lower band edge of the reflection curve. On the other hand, inspired by the wide-beam radiation of a circular patch loaded with parasitic monopoles, the proposed array is able to realize its beam scanning coverage of −60°–+60° with low sidelobe levels (SLLs) in its E-plane. The reflection and radiation properties are validated by full-wave simulation and measurement of an eight-element array prototype. The filtering and low-SLL performance benefit for the array to avoid out-of-band interferences and in-band ones from other directions when it scans in a wide-angular area. [ABSTRACT FROM AUTHOR]

An antenna design is presented for long-distance transmission in the unmanned aerial vehicle (UAV) application. This antenna is in a dipole configuration but with dual-mode operations of both dipole and monopole mechanisms. The monopole behavior becomes apparent when installed on the UAV platform to provide a large ground. To ensure both modes’ good integration to produce a broad bandwidth, the dipole arms are formed by H-slot loaded microstrips to create a slower phase velocity. The separation between adjacent harmonic resonances can be decreased. This antenna has good vertically polarized radiation and maximum gains near the horizontal plane to provide better long-distance connections. Various combinations of H-shaped slots are applied to examine the bandwidth behaviors. The achieved size is 90 mm, roughly 1/3 wavelengths at 1.25 GHz and 1/4 at 0.8 GHz. The bandwidth is larger than 50%. Numerical HFSS full-wave simulation and measurement results are compared to validate the feasibility. [ABSTRACT FROM AUTHOR]

A novel low-profile vertically polarized planar endfire smart antenna that can achieve 360° beam-steering and high beam-shaping capability is proposed. The microstrip antenna is printed on a single thin substrate with a vertically polarized omnidirectional driven source and 36 tunable slot-integrated microstrip vertically polarized resonators (SMVR) for shaping the endfire beams. To verify the design approach, a prototype operating at the 5 GHz WLAN band is fabricated and tested. The results show that the antenna operates from 5.55 to 5.75 GHz and is capable of scanning a single endfire beam from 0° to 360° in the full azimuth plane. The scanning resolution and the maximum realized gain are 15° and 8.2 dBi, respectively. Moreover, multiple radiation pattern shapes including omnidirectional beam, dual-beams, and tri-beams can also be generated by the antenna. The overall antenna height is only $0.06~\lambda $ at 5.6 GHz. This design provides a new antenna configuration for low-profile vertically polarized endfire beam-steering and beam-shaping antenna and is promising for future wireless communication systems with lost-cost beamforming property. [ABSTRACT FROM AUTHOR]

A compact fully metallic antenna with high endfire gain and vertical polarization is presented for applications that require the antenna to be mounted on large metallic platforms. The proposed structure includes one driven element on a ground plane, in addition to several parasitic directors and reflectors. The antenna behaves like a Yagi array, but with vertical polarization, where multiple directors and reflectors are used to enhance the endfire gain in the plane that contains the ground surface. The driven element is an upside-down U-shaped metallic strip with short vertical sides connected to the ground plane. The radiation is predominantly emitted from these vertical sides giving the antenna its vertical polarization radiation. Directors and reflectors are designed based on the driven element, with directors having the center of the U-shaped strip connected to the ground plane and reflectors without shorting pins in the middle. A prototype is fabricated with a volume of 104 $\times 55\times $ 6 mm3. The measured bandwidth is 18% (5.32–6.38 GHz). The variation of endfire gain is 2 dB around the nominal gain of 10.3 dBi across the bandwidth. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials have potential applications in nanoscale sensors and spintronic devices. Herein, motivated by experimental synthesis of a CrI 3 monolayer possessing intrinsic magnetism and a Janus MoSSe monolayer with piezoelectricity, we propose a 2D Janus Cr 2 I 3 F 3 monolayer as a multifunctional material exhibiting both piezoelectricity and ferromagnetism. Using density functional theory calculations, we systematically investigated the structural stability and the electronic, magnetic, and piezoelectric properties of the Janus Cr 2 I 3 F 3 monolayer. We predicted that a vertical polarization of up to −0.155 × 10 − 10 C/m is induced in the Cr 2 I 3 F 3 monolayer due to the breaking of symmetry. The origination mechanism of polarization was demonstrated in terms of a local dipole moment calculated by maximally localized Wannier functions. Meanwhile, it was found that a remarkable piezoelectric response can be produced under a uniaxial strain in the basal plane. The calculated piezoelectric coefficients of the Cr 2 I 3 F 3 monolayer compare favorably with those of the frequently used bulk piezoelectric materials such as α –quartz and wurtzite AlN. Particularly, the e 31 and d 31 values of the Cr 2 I 3 F 3 monolayer are nearly 10 times as large as that of Mo-based transition metal dichalcogenides. We also found that the magnitude of e 31 mainly arises from the ionic contribution, while the electronic contribution can be nearly neglected. The considerable piezoelectric response combined with the intrinsic magnetism make the Janus Cr 2 I 3 F 3 monolayer a potential candidate for novel multifunctional devices integrating both piezoelectric and spintronic applications. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials 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.)

In this article, a meander line internal antenna used for wireless terminal is proposed. The current of this antenna is mostly distributed on the antenna radiator itself, rather than on the main board of the wireless device. As a result, the chance of having radio-frequency (RF) interference issues, which usually result in receiver desensitization in wireless radios, can be significantly reduced. The antenna has good radiation performance in the vertical polarization with a low physical profile, compared with the existing antenna designs for typical wireless terminals. The antenna has efficiency similar to the monopole antenna with much less reference/ground plane dependence, achieving lower RF interference, which is demonstrated by the noise coupling measurements in a predefined digital clock - antenna configuration. Furthermore, the mutual coupling (i.e., isolation) between two such antennas is studied and the envelope correlation coefficient between the two antennas is found to be low. A router assembled with the two proposed antennas is tested, and the total isotropic sensitivity is found lower compared with monopole antennas, due to the characteristics of low RF interference and high isolation of the proposed antenna. [ABSTRACT FROM AUTHOR]

Vertically polarized, omnidirectional- and endfire-radiating, bandwidth-enhanced, high efficiency, electrically small monopole filtennas are developed. Both designs are attained by organically combining a coax-fed top-hat loaded monopole with two hybrid quarter-wavelength open-end stubs and a shorting post. The hybrid stubs serve two functions. They produce two radiation nulls at both the lower and upper band edges to sharpen the roll-off rate. Moreover, they facilitate the appearance of an additional resonance without affecting the original resonant mode. The shorting post is introduced to engineer the overlap of two resonant modes to yield an enhanced bandwidth. Prototypes of both filtennas were fabricated, assembled, and tested. The measured results are in good agreement with their simulated values, validating their efficacy. The omnidirectional filtenna has an electrically small size (ka = 0.73), a fractional bandwidth (FBW) of 11.3%, and a maximum realized gain of 3.01 dBi. The endfire-radiating filtenna has an electrically small size (ka = 0.93), an operating FBW of 12.8%, and a peak realized gain of 6.09 dBi. Both filtennas exhibit a flat realized gain response and high radiation efficiencies over their entire passbands, as well as very good selectivity with high out-of-band suppression levels. [ABSTRACT FROM AUTHOR]

This paper presents a method for calculating the site attenuation (SA) of an open-area test site (OATS) for a pair of calculable dipole antennas with a 3-dB hybrid balun in the frequency range of 30 MHz to 1 GHz. The SA was directly derived using the concept of power mismatch and dissipative loss from the SA measurement system instead of the concept of substitution loss. Two types of SA formulas using the power loss concept on the treatment of the OATS are presented. The first is the SA formula related to knowing only the value of the SA. The other is the SA formula that analyzed the effects of each part of the SA. Additionally, the constituent losses of the SA measurement system are discussed using the derived SA formula. The analysis of the results showed that the SA could be successfully characterized individually from the loss of the OATS. It also showed that SA is expressed as two kinds of losses: the balanced port-mismatch losses of transmit and receive baluns and the half-space dissipative loss. The resultant SA showed good agreement with the results calculated from the S-parameters as well as with the measured results.

Tip‐enhanced Raman spectroscopy has already promised extremely high plasmonic enhancement due to the successful optical confinement inside the nanocavity or sub‐nanocavity between the tip apex and substrate. Yet the dipole‐like charge oscillation enabled the gap enhancement, and hence, only the vertical polarization component could match and contribute to the overall efficiency. To avoid the noise and pursuit the mode purity, we chose the vector beam to form a tightly focused vertical electric field to generate such a "hot‐spot." For the bottom illuminated method, taking the opaqueness and absorption characteristics of the beam by the metal substrate into consideration, the substrate thickness becomes the critical factor concerning gap plasmons coupling effect and incident light transmittance. Here, the spatial resolution lines of the vector beam excited from the bottom were compared with that of side method excited by linearly polarized beam, which shows that the vector beam presents greater symmetric characteristics. In addition to better elucidating the mechanism of tip‐enhanced Raman spectroscopy, our results can be applied to a rational reference and guidance for later experiments. [ABSTRACT FROM AUTHOR]

A compact wideband vertically polarized endfire antenna operating at millimeter-wave (mmWave) is proposed. The wideband characteristic is achieved by combining three resonances which are, respectively, formulated using slot, dielectric, and cavity resonators. The compact topology is realized through the employment of dielectric loading technique. The proposed via-structured antenna element is designed to operate from 25.8 to 40.1 GHz, which represents a bandwidth of 43.4%. The antenna features a compact size of $0.37\times 0.45\times 0.17\,\,\lambda _{\mathrm {max}}^{3}$ ($4.3\times 5.2\times 2$ mm3), where $\lambda _{\mathrm {max}}$ is the free-space wavelength at the lowest frequency. The element realized gain varies from 3.5 to 7.6 dBi. A detailed performance analysis is provided, which helps to understand the principle of operation of the proposed antenna. The dielectric situated in the frontside of the cavity features a dual-function: 1) a resonator to generate the second resonance and 2) an impedance matching layer for the entire operating band. Two antenna array models are fabricated and examined for in-depth investigation. The first model contains a power divider for fixed beam analysis, and the second model is connected to the mmWave beamforming module to investigate the beam scanning capability of the proposed antenna. The simulated impedance bandwidth (reflection coefficient < −10 dB) of the four-element array equals 47.1% from 24.75 to 40 GHz and the realized gain varies from 6 to 11.4 dBi. The studies collectively ascertain that the proposed antenna features one of the most compact volumes while exhibiting one of the widest bandwidths to be reported in the literature. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials have potential applications in nanoscale sensors and spintronic devices. Herein, motivated by experimental synthesis of a CrI3 monolayer possessing intrinsic magnetism and a Janus MoSSe monolayer with piezoelectricity, we propose a 2D Janus Cr2I3F3 monolayer as a multifunctional material exhibiting both piezoelectricity and ferromagnetism. Using density functional theory calculations, we systematically investigated the structural stability and the electronic, magnetic, and piezoelectric properties of the Janus Cr2I3F3 monolayer. We predicted that a vertical polarization of up to −0.155 × 10−10 C/m is induced in the Cr2I3F3 monolayer due to the breaking of symmetry. The origination mechanism of polarization was demonstrated in terms of a local dipole moment calculated by maximally localized Wannier functions. Meanwhile, it was found that a remarkable piezoelectric response can be produced under a uniaxial strain in the basal plane. The calculated piezoelectric coefficients of the Cr2I3F3 monolayer compare favorably with those of the frequently used bulk piezoelectric materials such as α–quartz and wurtzite AlN. Particularly, the e31 and d31 values of the Cr2I3F3 monolayer are nearly 10 times as large as that of Mo-based transition metal dichalcogenides. We also found that the magnitude of e31 mainly arises from the ionic contribution, while the electronic contribution can be nearly neglected. The considerable piezoelectric response combined with the intrinsic magnetism make the Janus Cr2I3F3 monolayer a potential candidate for novel multifunctional devices integrating both piezoelectric and spintronic applications.

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering 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.)

This communication proposes a compact, low-profile patch antenna with omnidirectional radiation pattern and vertical polarization. A pair of shorted patches are excited in-phase to achieve the omnidirectivity and the vertical polarization, simultaneously. The principle is to excite two back-to-back arranged shorted patches to generate symmetrical electric-field ($E$ -field) distributions normal to the ground plane. Analytical study on how to generate the omnidirectional radiation pattern is carried out. Based on this study, we found that the spacing in between the two patches have little influence on the radiation characteristics, which provides another flexibility in the design. In addition, the shape of the patch and the corresponding field distribution are investigated to further improve the omnidirectivity. To improve the impedance bandwidth, resonant structures are inserted in between the patches, producing the second-order response in frequency. The antenna has been fabricated and characterized, and the measured results are in reasonable agreement with the simulations, showing that the proposed antenna is suitable for potential surface-mount wireless applications. [ABSTRACT FROM AUTHOR]

A novel low-profile vertically polarized wideband monopole antenna is proposed. A central-fed circular patch antenna, which is shorted concentrically by three metal pins, is initially adopted to excite TM01 and TM02 modes. Then, a fan-shaped clearance area is cut out in the angular area between each two shorting pins. Finally, three mushroomlike structures are placed in the clearance area, which, together with the feeding probe, form three split ring resonators (SRRs) that introduce an extra resonance, thereby substantially expanding the antenna operation bandwidth. All the three modes have radiation patterns similar to the conventional monopole. The proposed antenna has a very low profile of 0.06 λmin and a lateral dimension of π × (0.176 λmin)2, where λmin is the free-space wavelength at the lowest frequency of operation. A simulated impedance bandwidth for |S11| < −10 dB of about 48.5% ranging from 1.7 to 2.79 GHz is achieved, which fully covers the 4G LTE band, while the measured result shows a wider fractional bandwidth of 66%. [ABSTRACT FROM AUTHOR]

A millimeter-wave (mmW) low-profile wideband magneto-electric (ME) monopole antenna with the vertically polarized endfire radiation is presented by combining a pair of the top-loaded electric monopoles with a thin open-ended substrate integrated waveguide (SIW) with the extended lower broad wall. The antenna has a profile of 0.19 wavelength at the center frequency of the operating band, a wide bandwidth of 60.7% (from 23.5 to 44 GHz) covering all the fifth-generation (5G) mmW bands in the Ka-band, a stable gain of around 7 dBi, and a tilted radiation pattern. Then a $1 \times 8$ ME-monopole array is designed to investigate the beam scanning properties and the effects of the metallic ground and the polycarbonate radome, which should be considered in practical applications. As a sample, a $1 \times 8$ array fed by an SIW feed network, assembled on a metallic ground plane, and covered by a polycarbonate radome is finally designed, fabricated, and measured. The prototype achieves promising radiation features with a gain up to 15.3 dBi. Owing to the compact low-profile structure with good performance, the proposed design would be valuable to the mmW applications. [ABSTRACT FROM AUTHOR]

This letter presents a wideband slotted substrate integrated waveguide (SIW) antenna for millimeter-wave (mm-wave) fifth-generation (5G) mobile handset applications. The antenna is vertically polarized and has a small clearance of 3.3 mm. To realize a wide operating bandwidth, two sets of vias are employed to perform a change in SIW height. Furthermore, a pair of U-shaped slots is used in both top and bottom faces of SIW to improve impedance matching and front-to-back radiation ratio. The antenna achieves a measured −6 dB bandwidth of 35.7% (23.4–33.6 GHz) and a −10 dB bandwidth of 17.4% (26.2–31.2 GHz). The beamforming capability of the antenna array is investigated. The antenna array has good scanning performance and achieves large spatial coverage. [ABSTRACT FROM AUTHOR]

A design of a flexible, uniplanar, vertically polarized, Yagi-configured, electrically small antenna (ESA) that can be conformally mounted on a conducting cylinder with a small radius for endfire radiation is presented. To create a Yagi-configured antenna with both an electrically small size and uniplanar configuration, an interdigital structure is utilized to divide the top-hat of the driven monopole into two parts, and a C-shaped slot is etched at the top-hat of the reflecting monopole to significantly lower its resonant frequency. The ESA’s stable radiation performance characteristics were maintained when it was mounted on small conducting cylinders with different radii. A 6-element array prototype that entirely encircles a conducting cylinder with only a 50 mm radius was fabricated and measured. The measured results, which are in good agreement with their simulated values, demonstrate that, with a low profile ($0.035\lambda _{\mathrm {L}}$) and electrically small size (ka = 0.82), the proposed vertically polarized antenna can operate in a frequency range centered at 1.7 GHz, and exhibits an 8.2% impedance bandwidth and a 6.4 dBi peak realized gain. Because it has the advantages of electrically small size and flexibility to conform to the conducting cylinder with small radius, it should be very attractive for many miniaturized aircraft in the future. [ABSTRACT FROM AUTHOR]

A vertically polarized, low-profile, compact, near-field resonant parasitic antenna with pattern reconfigurability is demonstrated. The antenna has three dynamic end-fire states facilitated with only three p-i-n diodes. The radiation pattern in each state covers more than 120° in its azimuth plane and, hence, it achieves beam scanning that covers the entire azimuth plane. The antenna height and transverse size are, respectively, only $0.048\lambda _{0}$ and $0.1\lambda _{0}^{2}$. Measured results, in good agreement with their simulated values, demonstrate that the antenna exhibits a ~11% fractional impedance bandwidth, and a ~6.6 dBi peak realized gain in all three of its pattern-reconfigurable states. Stable and high peak realized gain values are realized over its entire operational band surrounding 2.22 GHz. [ABSTRACT FROM AUTHOR]

A low-profile broadband quasi-bidirectional antenna with vertical polarization is proposed. Two groups of parasitic patches placed close to the excited grounded patch are used to enhance the bandwidth of this antenna. A group of parasitic patches can induce two resonant valleys, and the other group of parasitic patch can induce another resonance to reduce the high reflection between the two previously mentioned resonant valleys. The operational bandwidth of this antenna can reach 17.5% by combining the three resonances. This antenna has a low profile of 0.04λ and can emit vertically polarized quasi-bidirectional beams over the whole operational frequency band. [ABSTRACT FROM AUTHOR]

A low-profile planar Yagi–Uda antenna with exact endfire radiation and vertical polarization is presented in this paper. The concept is the combination of an aperture element and a novel vertical I-shaped resonator (VISR). The aperture acts as the driven antenna, which can be equivalent of a virtual magnetic dipole. The VISR array constructed with VISR unit cell is employed as a director or a reflector element depending on the resonant frequency of the unit cell, which consists of two identical rectangular metal conductors printed on both sides of a substrate and their electrical connection using via holes. Two prototype antennas are then designed, fabricated, and measured to test the validity of the operating principle. Antenna I with one director and one reflector achieves an endfire realized gain of 9.9–10.3 dBi and a front-to-back ratio (FBR) of more than 17.4 dB across 6.36–6.70 GHz. With four directors and one reflector, an endfire realized gain of 12.9–13.6 dBi and an FBR of more than 17.9 dB are accomplished by antenna II across 6.38–6.71 GHz. Moreover, a sensitivity analysis is implemented for the proposed antennas. Simulated results show that the standard PCB process is a reliable method for antenna fabrication. [ABSTRACT FROM AUTHOR]

A low-profile pattern-reconfigurable vertically polarized antenna is proposed. The reconfigurable antenna with a profile of about 0.06 wavelengths can emit three different vertically polarized beams, which are two directional beams and a quasi-bidirectional beam. The overlapped measured band of the three statuses has a bandwidth of 11.3%, which covers the operational bands of EN 302 663 and 802.11p–1609.x standards used in intelligent transportation systems. [ABSTRACT FROM AUTHOR]

Atomically thin Bi2O2Se has been recently synthesized, and it possesses ultrahigh mobility (Nat. Nanotechnol. 2017, 12, 530; Nano Lett. 2017, 17, 3021). Herein, we show first-principles evidence that Bi2O2Se and a related class of bismuth oxychalcogenides, such as Bi2O2S and Bi2O2Te, not only are novel semiconductors with ultrahigh mobility but also possess previously unreported ferroelectricity/ferroelasticity. Such a unique combination of semiconducting with ferroelectric/ferroelastic properties enables bismuth oxychalcogenides to potentially meet a great challenge, that is, integration of room-temperature functional nonvolatile memories into future nanocircuits. Specifically, we predict that bulk Bi2O2S is both ferroelastic and antiferroelectric and that a thin film with odd number of layers can even be multiferroic with nonzero in-plane polarization, and this polarization can be switchable via ferroelasticity. Moreover, Bi2O2Te possesses intrinsic out-of-plane ferroelectricity, while Bi2O2Se possesses piezoelectricity and ferroelectricity upon an in-plane strain. The in-plane strain on Bi2O2Se can induce giant polarizations (56.1 μC/cm² upon 4.1% strain) with the piezoelectric coefficient being about 35 times higher than that of MoS2 monolayer. The in-plane strain can also enhance the bandgap or even convert indirect to direct bandgap beyond a critical value. The good match among the lattice constants of bismuth oxychalcogenides is also desirable, rendering the epitaxial growth of heterostructure devices free of fabrication issues related to lattice mismatch, thereby allowing high-quality bismuth oxychalcogenide heterostructures tailored by design for a variety of applications. [ABSTRACT FROM AUTHOR]

In this paper, a meander line internal antenna used for wireless terminal is proposed. The current of this antenna is mostly distributed on the antenna radiator itself, rather than on the main board of the wireless device. As a result, the chance of having intrasystem electromagnetic compatibility issues, which usually result in receiver desensitization in wireless radios, can be significantly reduced. The antenna has good radiation performance in the vertical polarization with a low physical profile, compared to the existing antenna designs for typical wireless terminals. The antenna has efficiency similar to the monopole antenna with much less reference/ground plane dependence, which is important for high sensitivity radio design. Further, the mutual coupling (i.e., isolation) between the two such antennas is studied and the envelope correlation coefficient between the two such antennas when they are placed in one system is found to be low, which is important for better throughput for a multiple input and multiple output system. Both simulation and measurement results demonstrate the proposed design. [ABSTRACT FROM PUBLISHER]

For the first time a vertically polarized electron beam has been used for physics experiments at MAMI in the energy range between 180 and 855 MeV. The beam-normal single-spin asymmetry A n , which is a direct probe of higher-order photon exchange beyond the first Born approximation, has been measured in the reaction C 12 ( e → , e ′ ) C 12 . Vertical polarization orientation was necessary to measure this asymmetry with the existing experimental setup. In this paper we describe the procedure to orient the electron polarization vector vertically, and the concept of determining both its magnitude and orientation with the available setup. A sophisticated method has been developed to overcome the lack of a polarimeter setup sensitive to the vertical polarization component. [ABSTRACT FROM AUTHOR]

This paper proposes a compact wideband and low-profile antenna mountable on large metallic surfaces. Six rows of coupled microstrip resonators with different lengths are printed on a Teflon block. The lengths of the microstrip resonators in different rows are gradually reduced along the endfire direction. The first four rows of resonators provide four resonances at different frequencies for bandwidth enhancement. The last two rows of resonators are used as two directors to suppress sidelobe levels at high frequencies. A trapezoidal launcher is applied to serve as a reflector and provide one resonance at the lowest frequency. A trapezoid-shaped capacitive-feed strip is utilized and also printed on the Teflon block to globally optimize the wideband impedance matching. The proposed antenna covers a relative bandwidth of 109% for VSWR < 2 with a height of 0.044\lambda L and a volume of only 0.03\lambda L^{3} ( \lambda L being the free-space wavelength at the lowest operating frequency). Within the operating band, the realized gain is better than 6.5 dBi and the radiation efficiency is higher than 95%. [ABSTRACT FROM AUTHOR]

A novel design of a low-profile wideband monopolar antenna is proposed with integration examples for vehicles and helmets. Initially, a monopolar antenna size is reduced by adding four symmetrical tapered slots on an edge-shorted patch. The antenna is first designed to be integrated onto a large flat ground plane that is applicable for vehicular installation. This design is later adapted for integration onto a helmet with a finite-curved ground plane, where the helmet material is included as part of the design. This study shows that a curved ground plane improves the radiation patterns at broadside and further reduces the antenna height. Both vehicle and helmet antennas have been optimized to operate in a wide frequency range from about 800–2300 MHz. These antennas radiate in a monopole-like pattern with vertical polarization and high radiation efficiency that makes them suitable for transmission applications. Good agreement between simulation and measurement is obtained, which ultimately validates the proposed design technique. [ABSTRACT FROM PUBLISHER]

In this paper, the retrieval of sea surface current velocity from vertically polarized (V-pol) X-band marine radar data is presented. Three different methods, including the iterative least square approach, the normalized scalar product method, and the polar current shell algorithm, that have been used for horizontally polarized data are employed here. A comprehensive comparison of the performance of the three methods is conducted using the radar images collected by the V-pol radar deployed on the Forschungsplattformen in Nord- und Ostsee No. 3 (FINO3) offshore research platform and the acoustic Doppler current profiler (ADCP) data in the North Sea. The results indicate that all three methods are capable of providing reliable current speed and direction measurements from V-pol data, with similar performance. Based on the experimental data for which the current magnitude is less than 0.5 m/s, the radar-derived results agree best with the ADCP data at a depth of 6–8 m, with the root mean square difference for current velocity $x$- and $y$-components being 7.2–8.9 cm/s. The correlation coefficients between the radar-derived and ADCP-measured current velocity components are as high as 0.87–0.93. [ABSTRACT FROM AUTHOR]