3D Antenna Research Articles

A 3D wideband electromagnetic horn antenna applicator for biomedical applications

Abstract This paper proposes a new, compact, wideband 3D horn antenna for biomedical wireless applications such as cancer and tumor detection. In order to achieve the best penetration level, the antenna has been built and tuned to work in the low frequency range of 0.48–1.24 GHz, which can exhibit a high-resolution detection result. The proposed applicator is a double ridge horn antenna (DRHA). The layout and operation of the key needed components to assemble a wideband hyperthermia system are provided in this study. We assume a cylindrical human tissue phantom with wideband dispersive tissue properties, and simulation results are given. The resulting field maps are displayed in several planes to illustrate the energy localization process. The findings indicate that, in contrast to traditional narrowband systems, wideband operation may improve energy localization in deep tumor locations while eliminating hot spots. The suggested antenna was built and measured to verify the result.

Achieving Broadband Near‐Field Directionality with a 3D Active Janus Antenna

AbstractDirectional sources like the Huygens source enable electromagnetic wavefront forming/shaping with great flexibility and have made impacts in photonics, applied physics, metasurfaces, and antenna engineering. The related Janus source features a strongly directional near‐field and a quasi‐isotropic far‐field, which gives it promising application potentials distinct from, and complementary to, the Huygens source. Nevertheless, most existing Janus sources face strong limitations in efficiency and/or 3D operation, hindering their practical application. This paper introduces a 3D active Janus source that achieves near‐field directionality over a wide bandwidth and a power efficiency much improved over existing passive Janus sources. It is shown that a class of quasi‐isotropic antennas are actually active Janus sources (which is referred to as the Janus antenna). A well‐designed Janus antenna is demonstrated which (a) exhibits near‐field directionality over a broad bandwidth of 28.9%, and (b) in a practical usage environment, achieves a power efficiency ≈60 times higher than a passive Janus source. This work elucidates the connection between the “Janus dipole” concept in physics and the “quasi‐isotropic antenna” concept in antenna design, and paves the way for the design of future directional devices with much improved bandwidth and efficiency.

Experimental demonstration of a silicon nanophotonic antenna for far-field broadened optical phased arrays

Optical antennas play a pivotal role in interfacing integrated photonic circuits with free-space systems. Designing antennas for optical phased arrays ideally requires achieving compact antenna apertures, wide radiation angles, and high radiation efficiency all at once, which presents a significant challenge. Here, we experimentally demonstrate a novel ultra-compact silicon grating antenna, utilizing subwavelength grating nanostructures arranged in a transversally interleaved topology to control the antenna radiation pattern. Through near-field phase engineering, we increase the antenna’s far-field beam width beyond the Fraunhofer limit for a given aperture size. The antenna incorporates a single-etch grating and a Bragg reflector implemented on a 300-nm-thick silicon-on-insulator (SOI) platform. Experimental characterizations demonstrate a beam width of 44°×52° with −3.22 dB diffraction efficiency, for an aperture size of 3.4 μm×1.78 μm. Furthermore, to the best of our knowledge, a novel topology of a 2D antenna array is demonstrated for the first time, leveraging evanescently coupled architecture to yield a very compact antenna array. We validated the functionality of our antenna design through its integration into this new 2D array topology. Specifically, we demonstrate a small proof-of-concept two-dimensional optical phased array with 2×4 elements and a wide beam steering range of 19.3º × 39.7º. A path towards scalability and larger-scale integration is also demonstrated on the antenna array of 8×20 elements with a transverse beam steering of 31.4º.

High Gain Defected Slots 3D Antenna Structure for Millimeter Applications

The antenna is designed as a 3D structure and is made from a conductible cylindrical antenna cone. The cone structure is realized using etching of elliptical slot array on the antenna. We use a conductible circular reflector under the proposed cone and increase the gain of the antenna. The proposed antenna provides effective bandwidth from 1GHz to 30GHz, but the gain of the proposed antenna is varying between 3dBi and 15dBi in the frequency band we are interested in. Geometrical details of the antenna are optimized numerically using parametric study using CST MWS Software Package. Once the optimal design is arrived at, the results are validated with another software package using HFSS Simulation Technology. The obtained results from both software packages agree very well.

The configuration and detection characteristics of a 3D holographic LWD instrument antenna system based on multi-component EM induction theory

In order to improve the precision of electromagnetic resistivity logging, while ensuring the reliability of boundary detection and anisotropy identification, this study starts from the theory of multi-component electromagnetic induction. Through deriving the formula of component responses, the analytical expressions of electromagnetic wave fields are obtained for various coil pairs of azimuthal instruments. A 3D holographic LWD instrument antenna configuration is constructed, with co-planar and non-coplanar, tilted and orthogonal coil combinations, all components of the magnetic field tensor Hxx,Hxy,Hxz,Hyx,Hyy,Hyz,Hzx,Hzx,HzzHxx,Hxy,Hxz,Hyx,Hyy,Hyz,Hzx,Hzx,Hzz are successfully resolved. With the combination of some or all components, functional signals are generated for specific detection objectives. Numerical simulation of the response of those signals shows that the distance of boundary detection and anisotropy identification capability are superior to traditional geo-signals. The response relationship shows that as the contrast of the formation resistivity decreases and the well deviation angle increases, the anisotropy identification capability gradually strengthens, and the signal strength and identification capability are better at frequency in the range of 400–600 kHz. The proposed antenna configuration has the potential to significantly enhance formation evaluation and to improve geo-steering capability, contributing technology-wise to the optimal landing trajectory and best wellbore position, resulting in cost saving and maximize oil & gas production.

3D Antenna array for multi-user massive MIMO system to minimize unfavorable propagation

Unfavorable propagation in massive multiple input multiple output (MIMO) systems is an underlying channel condition that reduces the gains offered by the system in terms of parallel channels. This paper presents a study on different types of antenna array configurations at base station (BS) to minimize unfavorable propagation conditions. Unfavorable propagation results in increased correlation between channel vectors of two or more mobile terminals (MTs) which arises when the signals from two or more MTs have small angular separation and small angular spread. The study starts with the investigation of the conventional uniform linear array (ULA) under different propagation conditions using a geometrical channel model based on a single cluster of scatterers per MT to quantify the performance degradation in unfavorable propagation. Subsequently, the performance of other types of array geometries is investigated. A custom cluster-based geometrical channel model is used in this study which includes practical propagation aspects like multipath fading, shadow fading, and the effect of BS height. Further, the study considers two cases: micro-cell and macro-cell. Under space constraint settings in terms of the maximum dimension of the array, the proposed technique uses randomized antenna locations in the array to minimize the effect of unfavorable propagation. Based on the results on performance parameters like user correlation and capacity, the study reveals that an antenna array configuration comprising of elements distributed random-homogeneously in a spherical shell outperforms other configurations.

2D leaky-wave antenna with controlled direction of radiation in the azimuthal plane

Abstract This paper presents a two-dimensional (2D) metasurface antenna array composed of mushroom cells coupled by thin slots in the top metallization. The antenna is fed through power dividers designed in substrate-integrated waveguide technology. The antenna structure is therefore designed in a fully up-to-date integrated version. The array shows beam steering in the azimuthal plane controlled by signal amplitudes fed into particular ports at the edges of the matrix. The main advantage of this antenna is no need to use phase shifters applied in standard 2D antenna arrays. Two antenna versions have been designed, fabricated, and experimentally tested. The beam can be steered within 360° (90°) in azimuth. The steering of the beam in elevation from backward to forward directions within 40° is done by changing frequency from 21 up to 23.8 GHz. This interval is reduced to 30° by exciting the antenna simultaneously at two adjacent ports at the same amplitude.

Study of solar brightness profiles in the 18–26 GHz frequency range with INAF radio telescopes

Context. One of the most important objectives of solar physics is to gain a physical understanding of the solar atmosphere, whose structure can also be described in terms of the density (N) and temperature (T) distributions of the atmospheric matter. Several multi-frequency analyses have shown that the characteristics of these distributions are still under debate, especially for outer coronal emission. Aims. We aim to constrain the T and N distributions of the solar atmosphere through observations in the centimetric radio domain. We employed single-dish observations from two of the INAF radio telescopes at the K-band frequencies (18–26 GHz). We investigated the origin of the significant brightness temperature (TB) detected up to the upper corona (at an altitude of ∼800 mm with respect to the photospheric solar surface). Methods. To probe the physical origin of the atmospheric emission and to constrain instrumental biases, we reproduced the solar signal by convolving specific 2D antenna beam models. We performed an analysis of the solar atmosphere by adopting a physical model that assumes the thermal bremsstrahlung as the emission mechanism, with specific T and N distributions. We compared the modelled TB profiles with those observed by averaging solar maps obtained at 18.3 and 25.8 GHz during the minimum of solar activity (2018–2020). Results. We probed any possible discrepancies between the T and N distributions assumed from the model and those derived from our measurements. The T and N distributions are compatible (within a 25% of uncertainty) with the model up to ∼60 mm and ∼100 mm in altitude, respectively. Conclusions. Our analysis of the role of the antenna beam pattern on our solar maps proves the physical nature of the atmospheric emission in our images up to the coronal tails seen in our TB profiles. Our results suggest that the modelled T and N distributions are in good agreement (within 25% of uncertainty) with our solar maps up to altitudes of ≲100 mm. A subsequent, more challenging analysis of the coronal radio emission at higher altitudes, together with the data from satellite instruments, will require further multi-frequency measurements.

A 3D Array High-Gain Vivaldi Antenna Design

This article designs a 3D array high-gain Vivaldi antenna suitable for K-band. First, by adding a positive trapezoidal dielectric structure to the radiation port of the original Vivaldi antenna unit, the purpose is to increase the gain of the Vivaldi antenna unit. The Vivaldi antenna unit was simulated and analyzed through HFSS software to obtain a new Vivaldi antenna unit with a frequency band width of 20GHz-26.4GHz and a gain of 10.8dB.Wider bandwidth, improved gain performance and enhanced directionality of the Vivaldi antenna unit compared to the original antenna. A 4-cell antenna array with a 3D structure is designed in order to be suitable for smaller planar size operating environments, and the antenna structure is further analyzed by...In this paper, the power division feed network conforming to this array is designed and the performance of this 2×2 antenna array is investigated, and the simulation results show that this array has good bandwidth and radiation performance, strong directionality, and almost no offset angle in the E-plane.

Clustered jamming in U-V2X communications with 3D antenna beam-width fluctuations

Jamming is the disruption of wireless communication signals, rendering them unreadable or degraded, typically caused by jamming devices. Clustered jamming in vehicular communications is a highly sophisticated attack technique characterized by the coordinated deployment of multiple jammers with the strategic intent to deliberately disrupt and incapacitate communication links, thereby presenting a formidable challenge to the reliability and security of vehicular networks. It is critical to address the intricate challenges imposed by clustered jamming in the context of vehicle-to-everything (V2X) communications augmented by unmanned aerial vehicles (UAVs), given their critical role in facilitating essential vehicle-to-vehicle and vehicle-to-UAV communication links. In this paper, we examine UAV-V2X (U-V2X) communications within the context of clustered jamming and the variations in the 3D beam-width of antennas. Also, mitigation techniques for clustered jamming in V2X communications are addressed. We consider the distribution of UAVs is governed by the Poisson point process, the distribution of vehicular-nodes (VNs) is governed by the Poisson line process, and the distribution of jammers is governed by the Matern Cluster Process. The analytical equations for the association probability and the success probability (SP) of a typical VN with the UAV and near-by VN, along with the presence of jammers and the variations of antenna beam-width are provided. Furthermore, we investigate the SP and spectral efficiency performance of the U-V2X network under different network configurations of UAVs, VNs, roads, jamming clusters, and transmit power of jamming devices. Our findings reveal that clustered jammers influence U-V2X network’s performance, further compounded by UAV beam-width fluctuations. Moreover, in low-density areas, UAVs demonstrate superior reliability for connectivity compared to VNs, despite clustered jamming. Also, lower UAV antenna fluctuations enhance UAVs’ dependability in U-V2X networks amidst clustered jamming. Specifically, for a given setup with τ= -5 dB, U-V2X link’s SP with jamming drops to one-quarter due to 2-degree beam-width fluctuations. Consequently, it is imperative to design and implement anti-jamming strategies, particularly as the number of jamming clusters and variations of antenna beam-width increase.

An Analytical Investigation on the Performance of 1D and 2D Antenna Arrays for mm-Wave Modern Communication Systems

Millimeter wave (mm-Wave) wireless technology has invaded every aspect of modern life because of its ability to transmit data quickly and securely. This paper presented a square patch antenna at a resonance frequency of 26.2GHz for millimeter wave wireless communication. The proposed antenna consists of single square radiating element. The suggested antenna was designed using CST Microwave Studio’s version 2020 on a Rogers RO 3003 lossy substrate with a relative permittivity of 3 . The result of this paper shows a minimum S11 of 19.34 dB, a gain of 6.97dBi, with bandwidth of 2GHz at the resonant frequency of 26.2GHz. The gain was enhanced to 16dBi and 25.8dBi with a high radiation efficiency by converting the single element patch antenna to a uniform linear array of 8 elements and uniform planar array of 8 × 8 elements respectively. The simulation results show that despite the simple design of the patch (without holes and cracks), which facilitates manufacturing in a small size; However, it achieves higher gain than the more complex designs found in the previous literature to suit mm wave communication requirements. Also, we used CST Microwave Studio for simulation which provides two methods for implementing arrays: the array factor method, which builds virtual arrays (the direct method), or building arrays by repeating the elements depending on the required size of the array, A comparison has been conducted between the numerical analysis of both methods, and the results show that even though the numerical analysis of the second method gives more accurate results that can be close to a manufactured antenna array, it needs high processing ability and time. Creating arrays with array factor may save time and processing ability but the results may not be accurate. Therefore, a relation was driven to show the error that can be added to give precise results.

Theory and Design of a 3-D Antenna With Wideband Radiation Isotropy

Theory and Design of a 3-D Antenna With Wideband Radiation Isotropy

Analysis of Fluctuating Antenna Beamwidth in UAV-Assisted Cellular Networks

This paper investigates a cellular network assisted by unmanned aerial vehicles (UAVs) in the presence of a fluctuating 3-dimensional (3D) antenna beamwidth. The primary objective is to perform an analysis of typical user equipment (T-UE) performance with a specific focus on coverage probability and spectral efficiency (SE) in the presence of fluctuations of 3D antenna beamwidth. Within this analytical framework, the macro base stations (MBSs) are meticulously characterized through the application of an independent 2D homogeneous Poisson point process (PPP), while the low-altitude platforms (LAPs) are described using an independent 3D PPP. The study entails the derivation of association probabilities, determining the likelihood of the T-UE associating with MBSs, line-of-sight LAPs, and non-line-of-sight LAPs. Through rigorous mathematical analysis, the paper formulates precise analytical expressions that encapsulate the association and coverage probabilities, taking into account the inherent variability in the UAV antenna beamwidth. This research focuses on a thorough performance evaluation of the T-UE across diverse network configurations, encompassing LAP density, the transmission power of LAPs, and the critical signal-to-interference ratio threshold. The outcomes of this study distinctly underscore the substantial disruptive impact resulting from fluctuating beamwidth on the performance of the T-UE within the UAV-assisted cellular network. Additionally, this performance is further impacted by larger densities and transmission power of the LAP. Hence, it is imperative to take into account the influence of these fluctuations on network association, coverage, and SE whenever contemplating a UAV-assisted cellular network.

Adding realistic noise models to synthetic ground‐penetrating radar data

ABSTRACTCost‐effective computing capabilities have paved the road for the use of numerical modelling to develop advanced methods and applications of ground‐penetrating radar (GPR). Realistic synthetic data and the corresponding modelling techniques, respectively, should consider all subsurface and above‐ground aspects that influence GPR wave propagation and the characteristics of recorded signals. Critical aspects that can be realized in modern GPR modelling tools include heterogeneous and frequency‐dependent material properties, complex structures and interface geometries as well as three‐dimensional antenna models, including the interaction between the antenna and the subsurface. However, realistic noise related to the electronic components of a GPR system or ambient electromagnetic noise is often not considered, or simplified by assuming a white Gaussian noise model which is added to the modelled data. We present an approach to include realistic noise scenarios as typically observed in GPR field data into the flow of modelling synthetic GPR data. In our approach, we extract the noise from recorded GPR traces and add it to the modelled GPR data via a convolution‐based process. We illustrate our methodology using a modelling exercise, where we contaminate a synthetic two‐dimensional GPR dataset with frequency‐dependent noise recorded in an urban environment. Comparing our noise‐contaminated synthetic data with field data recorded in a similar environment illustrates that our method allows the generation of synthetic GPR with realistic noise characteristics and further highlights the limitations of assuming pure white Gaussian noise models.

Analysis of U-V2X Communications with Non-Clustered and Clustered Jamming in the Presence of Fluctuating UAV Beam Width

Jammers emit strong intentional jamming signals aiming to limit or block legitimate communications. The distribution of jammers, whether in non-clustered or clustered form, significantly influences the performance of vehicle-to-everything (V2X) networks. In addition, the fluctuations in the three-dimensional (3D) antenna beam width of unmanned aerial vehicles (UAVs) can exert a substantial impact on the network’s overall performance. This paper introduces a model for UAV-V2X (U-V2X) communications in mm-Wave bands, considering non-clustered and clustered jammers, as well as the varying 3D antenna beam width. The roads are modeled using a Poisson line process, vehicular nodes (VNs) are modeled using a 1D Poisson point process (PPP), and UAVs are modeled using a 3D PPP. The jammers are distributed in two ways: non-clustered and clustered distributions. Moreover, the fluctuations in the 3D antenna beam width follow a normal distribution. To this end, a typical node’s performance in U-V2X communications is evaluated for various network configurations, including the number of UAVs, VNs, roads, jammers, and jammer’s transmission power. The analytical expressions for the outage probability (OP) of VN to VN connection (i.e., V2V), VN to UAV connection (i.e., V2U2V), and an overall connection (i.e., U-V2X), under non-clustered and clustered jamming, along with the fluctuating antenna beam width, are derived. The results revealed that the performance of the U-V2X communications utilizing mm-Waves is significantly degraded with the non-clustered jamming in comparison with the clustered jamming. The fluctuations in the 3D beam width of the UAV antennas further compromise the network’s performance. Thus, accurate modeling of these fluctuations is crucial, particularly in the presence of non-clustered jammers. Furthermore, the system designers should focus on implementing additional anti-jamming countermeasures specifically targeting non-clustered jammers in U-V2X communications.

Analysis of Tempering Effects on LDS-MID and PCB Substrates for HF Applications

Mechatronic Integrated Devices or Molded Interconnect Devices (MID) are three-dimensional (3D) circuit carriers. They are mainly fabricated by laser direct structuring (LDS) and subsequent electroless copper plating of an injection molded 3D substrate. Such LDS-MID are used in many applications today, especially antennas. However, in high frequency (HF) systems in 5G and radar applications, the demand on 3D circuit carriers and antennas increases. Electroless copper, widely used in MID, has significantly lower electrical conductivity compared to pure copper. Its lower conductivity increases electrical loss, especially at higher frequencies, where signal budget is critical. Heat treatment of electroless copper deposits can improve their conductivity and adhesion to the 3D substrates. This paper investigates the effects induced by tempering processes on the metallization of LDS-MID substrates. As a reference, HF Printed Circuit Boards (PCB) substrates are also considered. Adhesion strength and conductivity measurements, as well as permittivity and loss angle measurements up to 1 GHz, were carried out before and after tempering processes. The main influencing factors on the tempering results were found to be tempering temperature, atmosphere, and time. Process parameters like the heating rate or applied surface finishes had only a minor impact on the results. It was found that tempering LDS-MID substrates can improve the copper adhesion and lower their electrical resistance significantly, especially for plastics with a high melting temperature. Both improvements could improve the reliability of LDS-MID, especially in high frequency applications. Firstly, because increased copper adhesion can prevent delamination and, secondly, because the lowered electrical resistance indicates, in accordance with the available literature, a more ductile copper metallization and thus a lower risk of microcracks.

Anomalous and inverse spin Hall effects in Pt1-xBix/(YLuBiCa)3(FeGa)5O12 heterojunction

A garnet film with spatial magnetic moment distribution has been grown on gadolinium gallium garnet wafer (111) crystal plane, by regulating liquid phase epitaxial growth parameters and sub-lattice ions substitution, then 10 nm Pt1-xBix (x = 2% – 8%) alloy film was deposited on the surface of the garnet films. A new spin heterojunction Pt1-xBix/(YLuBiCa)3(FeGa)5O12 with both inverse spin Hall effect (ISHE) and anomalous spin Hall effect (ASHE) was designed and fabricated. The spatial magnetic moment distribution of the heterojunction has been found, which lays the foundation of the spin heterojunction for multiple spin injection with both spin electron reverse injection and anomalous injection. Because Bi ions doping and substitution increases the spin–orbit torque and the mixed conductance of the heterojunction, an oblique ASHE voltage curve and an enhanced ISHE voltage curve with double resonance peak were observed. It was confirmed that the injection of spinning electron into the heterojunction can be enhanced with both the ISHE and ASHE effect by adjusting the spatial magnetic moment distribution, which is a foundation for the future application of spin wave 3D antenna and other devices.

Preparation and electromagnetic performance of a light-weight, thin, and high-gain three-dimensional woven hollow structure microstrip antenna

With the popularity of 5 G, there is an increasing request for a light, high-performance, and stable structure for wireless communication. To solve the problems of delamination cracking and its own heavy weight of the conventional microstrip antenna, this study used ultra-high molecular weight polyethylene (UHMWPE) filament tows and purple copper filament tows as raw materials to prepare 3D woven hollow structure microstrip antenna preforms on a common loom. Using the prepared preforms for reinforcement and resin as the matrix, the VARTM process was used to prepare a 3D woven hollow structure microstrip antenna with a height of 6.8 mm, a weight of 35 g, and a bulk density of 0.7 g/cm3. The combination of the electromagnetic performance test and HFSS software simulation shows that the antenna has excellent radiation performance with a gain of 7.5 dB and a measured VSWR of 1.25. The mechanical performance test results show that it can withstand a maximum compression load of 2982 N and a maximum bending load of 364 N with no obvious delamination at the fracture. It is light, thin, and load-bearing with excellent radiation performance. There will be great potential in the unmanned field and the space field in the future.

Bifurcation and mode transition of buckled ribbons under oblique compressions

Three-dimensional (3D) buckled ribbon mesostructures have important implications in a variety of engineering fields, because they can afford novel functionalities and unprecedented mechanical properties with optimized structural/material designs. In many scenarios of practical applications, buckled ribbons would undergo oblique compressions, which could potentially lead to functional degradation or even device failure. While extensive studies have been reported on buckled straight ribbons compressed by a horizontal indenter, oblique compressions with an inclined indenter still remain unexplored, where distinct deformation paths and high-order bifurcation would emerge. This work investigates bifurcation and mode transition of buckled ribbons through combined theoretical/computational modeling and experimental observations. Development of a theoretical model allows establishment of phase diagrams for three deformation paths and six deformation modes that could possibly emerge at different assembly or loading parameters. The multi-step bifurcation, which has been verified experimentally, can be attributed mainly to the Euler buckling of flattened segments or the instability of multiple waves. By harnessing the multi-step bifurcation, a tri-stable mesostructure with a buckled ribbon and an assistive position limiting ribbon is demonstrated, and used to design reconfigurable 3D antennas capable of finely tuning the central frequency or the radiation pattern.

Ridged Meandered Waveguides for 3-D Routing and Phase Delay Control and Its Application to Discrete Lenses

In this paper, an innovative procedure to design ridged meandered waveguides is introduced. By modulating the meandered centerline of a waveguide connecting two fixed points, new degrees of freedom to control the phase delay are obtained. Ridged meandered waveguides represent a good compromise between coaxial cables, which feature broadband operation and can be easily bended still introducing high losses and conventional waveguides, which are characterized by low losses but also narrow operational bandwidth. Ridged meandered waveguides are especially well-suited for isophase lattice expanders that can be used in beamforming networks, phased arrays or discrete 3D lens antennas. The article describes a methodology to design meandered waveguides, which is verified both analytically and experimentally through the synthesis, fabrication and test of a discrete 3D lens antenna in Ka-band (27.5-30 GHz) made using additive manufacturing.