Beam Tilt Research Articles

Design and optimization of dielectric resonator based MIMO antenna with beam tilting at mm-wave for enhanced 5G communication using machine learning

In this paper, a dual-port ceramic-based multiple-input multiple-output (MIMO) antenna is designed for operation at mm-wave frequencies. The design incorporates a partially reflecting surface (PRS) positioned above the dual-port antenna to facilitate beam tilting. Additionally, various machine learning (ML) algorithms are utilized to optimize the unit cell length and the distance between the Dielectric Resonator Antenna (DRA) and the PRS, thereby achieving the desired beam tilting characteristics. The ceramic element is excited through an aperture, which generates the HEM11δ mode in the cylindrical dielectric resonator antenna (CDRA). The proposed antenna demonstrates excellent port isolation, exceeding 35 dB, and operates effectively within the 25.9–27.4 GHz frequency range. The PRS enables a broadside beam tilt of ±30 degrees, incorporating pattern diversity into the design. These characteristics make the proposed antenna an ideal candidate for mm-wave vehicle-to-vehicle and 5G communication systems.

Generating optical vortex beams using cylindrical waveguides

As an initial step toward exciting optical vortices using high-power millimeter waves, this study developed a method for inducing vortex modes within a cylindrical waveguide using Gaussian beams. By examining the coupling between tilted and offset Gaussian beams and specific waveguide modes, appropriate tilt angles and offsets were obtained. Numerical simulations demonstrated that the vortex modes could be efficiently excited using four Gaussian beams. Furthermore, the results revealed that increasing the number of Gaussian beams improves the excitation efficiency of vortex modes.

Effects of primary aberration on the spatiotemporal optical vortex focus

A spatiotemporal optical vortex (STOV) with transverse orbital angular momentum has several potential applications. However, refractive index mismatch, beam tilt and optical path misalignment are often inevitable during the application of an optical system. To investigate the focusing field of light pulse, the effects of primary aberrations such as the spherical aberration, coma, and astigmatism were analyzed. The simulation results indicate that three-dimension spatiotemporal distributions of the focusing light pulse are affected by primary aberration. On the principal coordinate planes, coma can distort the intensity structure and shift the STOV focus perpendicular to the propagation direction, while spherical aberration and astigmatism induce the actual STOV focus to shift along the propagation direction. Astigmatism do not affect the intensity structure of spatiotemporal plane without spiral phase, but stretch the 3D STOV focus along one spatial axis. Coma and astigmatism are necessary to be avoided to obtain a perfect STOV focus. It is helpful to improve the applications of STOV focus, such as optical tweezers, microscopy, and communications.

The Doppler wind, temperature, and aerosol RMR lidar system at Kühlungsborn, Germany – Part 1: Technical specifications and capabilities

Abstract. This paper describes the technical specifications of the extensions made to the middle-atmospheric lidar facility at the Leibniz Institute of Atmospheric Physics in Kühlungsborn, Germany (54.12° N, 11.77° E). The upgrade complements the existing daylight-capable Rayleigh–Mie–Raman (RMR) temperature lidar with a nighttime-only RMR wind–temperature lidar. The new system comprises an independent lidar with laser, telescopes, and detectors, which is synchronized with and adapted to the (old) temperature lidar. As a result, with the combination of RMR lidars the atmosphere is probed with three (vertical and tilted) beams. This work intends to highlight the recent innovations in the construction of a Doppler–Rayleigh lidar system using the single-edge iodine-cell technique, which allows for the simultaneous measurement of wind, temperature, and aerosols. We will detail supporting subsystems that allow for a high degree of lidar automation and concisely provide key technical information about the system that will support readers in the development of additional RMR wind–temperature lidar systems. We show an example of time-resolved temperature and wind soundings reaching up to ∼ 90 km. These data agree well with ECMWF-IFS profiles between 35 and ∼ 50 km but show a much larger variability above. In the companion article, we will present the algorithm design and uncertainty budgets associated with the data processing chain.

Time localized tilted beams in nearly-degenerate laser cavities.

We show that nearly-degenerate Vertical External-Cavity Surface-Emitting Lasers may emit a set of tilted beams of individually addressable mode-locked pulses. These time localized beams feature a Gaussian profile and they are emitted in pairs with opposite transverse k-vector. Because they are phase locked, their interference leads to a non homothetic pattern in the near-field emission of the laser. In the simplest situation, when a single pair is emitted, this is a stripe pattern. Our analysis discloses the role of third order (spherical) aberrations of the cavity in stabilizing this spatio-temporal mode-locked regime and in selecting the value of the transverse k-vector.

Design of Series-Fed Circularly Polarized Beam-Tilted Antenna for Microwave Power Transmission in UAV Application

In response to the increasing deployment of unmanned aerial vehicles (UAVs) across various sectors, the demand for efficient microwave power transmission (MPT) systems for UAVs has become paramount. This study introduces series-fed circularly polarized (CP) and passively beam-tilted patch array antennas designed to enhance MPT in UAV applications, with the intention of addressing the needs related to extending flight times and improving operational efficiency. The radiating element of the proposed antennas employs the conventional model of the patch with truncated corners for CP operation, with transmission line lengths optimized for beam tilt to ensure precise energy transfer. Additionally, an open stub is integrated into the broadside series-fed antenna to improve impedance matching, which is crucial for maintaining signal integrity. The proposed design achieves right-hand circular polarization (RHCP) with an axial ratio (AR) below 3 dB across the operating band, indicative of its effectiveness in diverse UAV operational contexts. Prototypes of each proposed antenna were fabricated and measured according to the beam tilting angle. The measured RHCP realized gains of the proposed antennas are 14.59, 13.09, 13.07, and 10.71 dBic at the tilted angles of 0°, 15°, 30°, and 45°, respectively, at 5.84 GHz.

Broadband Circularly Polarized Microstrip Antenna With Customized Tilted Beam Based on Index-Modulated Folded Split Ring Resonator

Broadband Circularly Polarized Microstrip Antenna With Customized Tilted Beam Based on Index-Modulated Folded Split Ring Resonator

Beam‐tilting antenna with low profile and increased gain for 5G mobile applications

AbstractA low‐profile beam‐tilting antenna with enhanced gain at millimeter‐wave frequency for future 5G mobile applications is designed, and measured results are presented. The mechanism of beam tilting is explained using the proposed printed rectangular loop dipole antenna (RLDA) with three directors that operate at 37 to 40 GHz. The proposed design includes a printed RLDA, one rectangular director sandwiched between two reverse L‐shape directors separated by a 0.05λ0 gap and located 0.35λ0 from the antenna. The measured results, which are well accepted with simulations, show that the antenna's main beam in the E‐plane tilts between ±20° with respect to the end‐fire direction over 37 to 40 GHz. A gain enhancement of 3 dB is obtained with no beam tilt, whereas a gain enhancement of 1.5 dB is obtained with the tilted beam in comparison to the printed RLDA. The proposed design is smaller in size, with a footprint of 10.2 mm × 5 mm (1.3λ0 × 0.64λ0).

Asymmetric toughening in the lap shear of metamaterial structural adhesives.

Metamaterial structural adhesives (MSAs), whose properties primarily rely on structural design, offer promising advantages over traditional adhesives, including asymmetric, switchable, and programmable adhesion. However, the effects of thick backing structures on the adhesion properties remain largely underexplored. Herein, we investigate a series of MSAs featuring a thin adhesive layer and an asymmetric thick beam structure terminated with a film. We conduct lap shear tests on the MSAs with varying terminated film thickness (t) and beam tilting angle (θ) while maintaining an identical adhesive layer. For MSAs with a thick terminated film (t = 2 mm), the effective adhesion energy is double that of solid samples without compromising shear strength, consistent with the theoretical predictions based on the crack trapping mechanism. Conversely, for MSAs with a thin terminated film (t = 0.5 mm), the maximum shear strength and effective adhesion energy are ∼2.8 times and ∼18.6 times those of solid samples, respectively, deviating significantly from the theoretical predictions due to new crack initiations. We further explore adhesion asymmetry by tuning the beam tilting angle (θ). For MSAs with highly tilted beams (θ = 70.3°), we achieve a maximum adhesion strength asymmetry factor of τ2/τ1 ∼ 2.2 for a thick terminated film (t = 2 mm), and a maximum adhesion energy asymmetry factor of Γ1/Γ2 ∼ 5.3 for a thin terminated film (t = 0.5 mm). Our work provides useful insights for designing metamaterial structural adhesives suitable for robotic grippers, wall-climbing robots, and wearable devices, particularly those requiring asymmetric, switchable, and stimuli-responsive adhesion, and adhesives on rough surfaces or in underwater conditions.

A Compact Broadband Loop Complementary Source Antenna with Switchable Tilted Beams for Intelligent Communication

A Compact Broadband Loop Complementary Source Antenna with Switchable Tilted Beams for Intelligent Communication

Tunable 3D printed composite metamaterials with negative stiffness

The paper proposes a class of tunable metamaterials that use inclined beams to achieve instability in a rigid system. Three different beam tilt angles, 25°, 45°, and 60°, are evaluated in the form of unit cells using quasi-static compression tests and numerical simulations. Snap-through behavirous are characterised by structural stiffness and buckling load. Periodic and gradient structures are assembled and analysed by arranging the unit cells in rows and columns. Size effect analyses and parametric studies are carried out on various unit-cell arrangements and different beam angles. The proposed metamaterials are manufactured through fused filament fabrication 3D printing technology with a composite material, onyx. The results from experiments, finite element analysis, and analytical models are compared and evaluated. The structural stiffness and buckling load are shown to be positively related to the inclination angle of the tilted beams. The number of rows of unit cells governs the nonlinear mechanical response (number of snap-throughs) of multiple-layered structures. By increasing the number of rows and columns of unit cells, which are less prone to manufacturing defects, the reliability and repeatability of the structural properties of periodic/gradient structures could be improved. A design plot is also provided to predict and tune the snap-through behaviour of multiple-layered structures via beam angles and unit-cell arrangements.

EFFICIENCY IMPROVEMENT FOR ELECTRONICALLY STEERED DUAL-BEAM ANTENNA BY USING METAMATERIAL BASED RADOME

Efficiency improvement for electronically steered dual-beam antenna by using metamaterial based radome are a PCB based circular-patch antenna design for dual beam steering is presented. This design employs the symmetrical slots inserted into the surface at eight angles of circular-patch antenna, thus, the original circular-patch antenna is reconfigured as consisting of eight small square-patches placed on eight angles and separated by such the slots. The beam steering property of this antenna can be implemented by controlling the on/off state of PIN diodes, which connected between each small square-patches and main patch at each angle of the structure. When the diode is on, the small square-patch becomes a part of radiating patch, whereas is off, the small square-patch becomes the parasitic element. The antenna is designed for the future high altitude platform such as, drone, Aircraft, missile, etc. That can be tracked or commanded from its control station within the given range and without disconnection. This antenna is investigated at 5.8 GHz of frequency and provided the bandwidth at 113 MHz, which is high enough for the unmanned aerial vehicles UAVs application, The antenna provides the gain of 7.13 dB without meta radome and switchable the dual-beam in eight different space quadrants for the azimuth plane by exciting forward bias with binary sequence to the PIN diodes. While it provides the constant tilted beam of 35° and angular width (3dB) 52.4° in the elevation plane and efficiency improvement for the antenna provides a gain of 10.18 dB with meta radome, approximately.

Curved-Retrodirective Beamforming System to Improve Microwave Power Transmission Efficiency in the Fresnel Region

This paper presents a curved-retrodirective beamforming system for improving microwave power transmission efficiency in the Fresnel region. Since microwave power transmission in the far-field region has very low efficiency, studies on the Fresnel region are being actively conducted. In these studies, a retrodirective beamforming (RDB) technique is popular. The RDB system with a sub-array structure was a realistic structure that reduced system complexity. However, the transmission efficiency is lowered because the beamwidth of the transmitter antenna element is narrow. To solve this problem, this paper proposes a curved-retrodirective beamforming system that can focus the microwave power on the receiver. The proposed system uses the peak gain of the transmitter antenna element by using tilted beams to improve transmission efficiency. The system design method that can maximize the transmission efficiency is also presented depending on the given conditions such as transmission distance, characteristics of the transmitter and receiver antenna. The simulation showed a reduction in power leakage compared to the conventional system. The fabrication and measurement validated the efficiency improvement of the proposed system for IoT devices in the Fresnel region.

A Low-Profile Metasurface-Inspired Antenna With Tilted Beam Radiation

In this letter, a simple method of generating tilted beam radiation through a planar structure is presented based on mode synthesis. Under the guidance of this operating principle, a low profile metasurface-inspired antenna emitting tilted beam is designed with the aid of characteristic mode analysis. The radiation structure of this antenna is a printed non-uniform metasurface. A broadside radiation mode is supported by an etched slot while a bidirectional radiation mode is excited by a metal via with a parasite microstrip line simultaneously. Consequently, a tilted beam radiation can be obtained by combining these two modes. To verify the analysis and simulation, the metasurface antenna is fabricated and tested. Measurement result indicates that this proposed metasurface antenna can realize a tilted beam at 5.1 GHz towards 35 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> with a realized gain of 7.9 dBi and a low profile of 0.048 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _{0}$</tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _{0}$</tex-math></inline-formula> is the operating wavelength in free space).

2D Jackiw–Rebbi and trivial localized states in square interfaced binary waveguide lattices

We investigate optical analogs of two-dimensional (2D) Jackiw–Rebbi (JR) states and 2D trivial localized states in square interfaced binary waveguide lattices in the linear and nonlinear regimes of Kerr type. The 2D JR states can be formed in the square interfaced binary lattice during propagation of optical beams and turn out to be quite robust, especially in the linear and defocusing nonlinearity regime where established 2D JR state profiles are well conserved during propagation. The established profiles of nonlinear 2D JR states formed during propagation agree well with exact solutions obtained by using the Newton–Raphson method. The 2D nonlinear trivial localized states found by the successive approximation method are much broader than 2D JR states with the same peak amplitudes. The 2D JR states can also be well trapped within the central interface of the lattices even in the presence of an initial tilt of the input beam which can easily displace 2D trivial localized states in square interfaced binary waveguide lattices, 2D Dirac solitons in perfectly periodic binary waveguide lattices and other solitonic structures in the continuous media.

Slotted vertical wall for decoupling and beam tilt correction

Abstract An intra-band pattern-corrected decoupling vertical conducting wall is realized by dielectric substrate with conductor cladding on both side wall between two tightly spaced H-plane microstrip patches with λ0/20 edge-to-edge spacing. The wall is grounded and two symmetrical slots are etched on the vertical substrate. The measured results agree with the simulations, showing that the slotted vertical wall reduces the mutual coupling within the bandwidth to −30 dB and corrects the radiation beam tilt to be within −4.5° to 3° from the broadside direction. A gain reduction of 0.6 dB is observed compared to the gain without the slotted decoupling wall.

Vibrational control and resonance of a nonlinear tilted cantilever beam under multi-harmonic low and high-frequency excitations

This paper investigates the vibrational resonance and control of the response of a nonlinear tilted cantilever beam under combined multi-harmonic low and non-resonant, high-frequency excitations. The basic system considers the first mode of vibration of a nonlinear tilted beam under parametric and direct base excitation with the frequency components locked in 2:1 ratio. Such a system is susceptible to parametric amplification of resonance, which may be detrimental for structural health in many mechanical systems. The primary objective of the research is to investigate the non-trivial effects of non-resonant high-frequency excitation on parametric amplification, vibrational resonance and chaos in the system, which, to the best of the authors’ knowledge, is not reported previously in the literature. The slow dynamic equations of the system are obtained using the method of direct partition of motion (MDPM), which is then analysed using the harmonic balance method (HBM). It has been shown that the high-frequency base excitation considerably influences the effective damping and stiffness of the system under consideration. The results of the research demonstrate that high-frequency excitation can effectively control the parametric amplification by shifting the resonance curve in the frequency axis and eliminating undesirable bifurcations by increasing the effective damping. The phenomenon of vibrational resonance has been found for specific parameter values in the presence of high-frequency base excitation. Detail parametric studies are performed to reveal the system’s rich nonlinear dynamics and bifurcations, like multiple jumps in response, dual peaks, isolated resonance response (isola), loop formation in frequency response plot, etc. The numerical results reveal that high-frequency excitation transforms chaotic responses into regular periodic responses. Direct numerical simulations are performed in MATLAB SIMULINK to validate the analytical results.

Embedding antennas with tilted beam patterns into parabolic wave equation‐based models for tunnel propagation

AbstractAccurate radio wave prediction models are necessary for the innovation of mobile communication technology and the deployment of wireless sensor networks in railways. The parabolic wave equation (PWE) method is one commonly used method to predict the electromagnetic characteristic of long railway tunnels. However, the advent of novel antennas and technologies (e.g., beam steering, beamforming) has posed new challenges to PWE‐based models such as effective means of taking tilted beam patterns into account. This study addresses such a challenge by using tilted Gaussian beams to embed antennas with oriented patterns or tilted beam directions into PWE‐based models. The proposed approach does not reduce the simulation efficiency of PWE itself. The validity and practicability of the technique are demonstrated by comparing against ray‐tracing as well as experimental measurements in various tunnel environments.

Stabilization of low-threshold two-plasmon parametric decay instability at oblique incidence of a microwave pump beam onto the plasma

It is shown that with an oblique incidence of a pump microwave in X2-mode electron cyclotron plasma heating (ECRH) experiments, the threshold power of a parametric decay instability (PDI) leading to excitation of two trapped upper hybrid waves increases and the anomalous absorption level decreases. It is proposed to use a small pump beam tilt along the magnetic field to suppress this most dangerous PDI, often observed in the X2-mode ECRH experiments.

Design and Development of Parasitic Elements Loaded Quadband Frequency and Pattern Reconfigurable Antenna

Modern communication demands a low-profile, versatile antenna. In this paper, a low-profile antenna of size 38 × 40 × 0.787 m m 3 is proposed to reconfigure frequency and radiation pattern. The Rogers RT Duroid 5870 of dielectric constant 2.33 is used as a substrate. Frequency reconfiguration is achieved by connecting patches of different lengths corresponding to the resonant frequencies through three PIN diode switches. Switching on/off these three diodes results in frequency switching between four distinct frequency bands. The Yagi-Uda principle is utilized to alter the radiation pattern. Simple parasitic elements are loaded on either side of the radiating structure. Changing the electrical lengths of the parasitic elements using PIN diode switches facilitates pattern reconfiguration by making them behave as a reflector/director. The presented structure resonates at four distinct frequencies (5.3 GHz/3.82 GHz/2.77 GHz/2.2 GHz) with a maximum of three beam tilt angles for each resonating frequency. SMP1345-079LF PIN diode is used for switching operation. Biasing circuit has been designed to ensure RF and DC isolation. The proposed antenna offers acceptable radiation performance in all the switching states. The average measured gains are 2.43 dBi, 2.42 dBi, 3.5 dBi, and 3.29 dBi at 5.3 GHz, 3.82 GHz, 2.77 GHz, and 2.2 GHz, respectively. On an average, the proposed antenna exhibits the simulated efficiency of 81%. The proposed antenna is suitable for 5G communication as its bandwidth covers band 1, band 7, band 46, and band 77 of the 5G new radio (NR) standard. Fabrication and testing are done to validate the results.