Ground Structure Method Research Articles

A Novel 4-port MIMO Antenna with Chamfered Edge for 5G NR n77/n78/n79 Bands and WLAN Applications

Abstract A novel, compact and low-cost four-element multiple-input multiple-output (MIMO) antenna with a high gain is proposed in this work. The suggested antenna structure uses easily accessible substrate material and has been designed and simulated using Ansys HFSS 3D electromagnetic simulation software. The radiating elements are placed orthogonally, and each of them consists of two circular rings. To improve the impedance matching and reduce mutual coupling, the corners are chamfered and partial ground structure is applied. For further enhancement in isolation, Defected Ground Structure (DGS) method is applied which makes the isolation as high as -55 dB. The measured gain of the proposed antenna is more than 12 dB over the considered frequency range. The antenna covers a frequency range from 3.3-6 GHz. The value of diversity gain is found to be more than 9.99 dB and envelope correlation coefficient is less than 0.006 respectively. Also, the mean effective gain, channel capacity loss, and total active reflection coefficient results are within the optimal range. These make the designed antenna suitable for the sub-6 GHz, 5G new radio (NR) n77/n78/n79 where n77 (3.3-4.2 GHz), n78 (3.3-3.8 GHz), and n79 (4.4-5 GHz) bands along with WLAN (5.1-5.8 GHz) applications.

Improved design and performance of the global rectenna system for wireless power transmission applications around 2.45 GHz

This work proposes a new conception of the global microstrip rectenna system operating around 2.45 GHz. This improved rectenna system associates a receiving antenna with a rectifier circuit. This rectenna is printed on an FR4 substrate. The proposed antenna is a 1×4 microstrip antenna patch array with pentagonal patches using the defective ground structure method and operates with circular polarization. To show the effectiveness of this array, the results obtained by the computer simulation technology microwave studio (CST MWS) software prove that this array is good in terms of high gain, high directivity, high efficiency, wideband, small volume, and well-adaptation, and all these results are confirmed by another solver high-frequency structure simulator (HFSS). The improved rectifier is a microstrip rectifier that uses an HSMS2852 Schottky diode by using a series topology. The effectiveness of this rectifier is proved by the simulation results using advanced design system (ADS) software in terms of well-matching input impedance, high efficiency, and important output direct current (DC) voltage value. The proposed rectenna system is more efficient compared with the existing works and is very appropriate for several applications of wireless power transmission to power supply electronic instruments in various fields cleanly on our planet.

Integrated vehicle chassis fabricated by wire and arc additive manufacturing: structure generation, printing radian optimisation, and performance prediction

ABSTRACT In the automotive industry, the extended design and iteration cycles for integrated chassis typically span 2–3 years, creating a misalignment with swiftly changing market demands. Wire arc additive manufacturing (WAAM) technology presents a viable alternative, overcoming the limitations of conventional chassis production. Our holistic framework significantly condenses the design, optimisation, and validation stages for automotive chassis. Initially, a ground structure method is utilised to outline and generate a skeleton chassis. We then utilise the OpenCV image processing method to select a hollow skeleton chassis with minimal material occupancy (0.476) and suspension printing. Subsequently, we assess the influence of printing radian variations by the robotic arm on the microstructure and stress, employing a cellular automaton-finite element (CA-FE) model at the 150th and 200th layer benchmarks. A Kalman filter (KF) is also implemented to fine-tune the printing radian in regions with coarse grain structures and elevated solute concentrations. The process concludes with collision and modal simulation verifications of the skeleton chassis, affirming the optimisation's success. This streamlined methodology allows the completion of the chassis design and manufacturing cycle within a remarkably condensed time frame of one week, accelerating the development process by a factor of 120.

Design of Rectangular Patch Microstrip Antenna with Defected Ground Structure Method at 3.5 GHz Frequency for 5G Technology

5G technology is currently developing rapidly in various countries. 5G technology has three sub-frequencies: low band, midband and high band. Midband frequencies in Indonesia are between 2.6 GHz and 3.5 GHz. In order for 5G technology is able to be used in Indonesia, it needs an antenna that can work at 3.5 GHz and has a wide bandwidth. Microstrip antenna is a simple and efficient antenna. However, microstrip antenna has minimal bandwidth. To overcome this, certain methods are needed, one of which is the defected ground structure (DGS) method. The initial design of the antenna has dimensions according to the results of the calculation formula. Then optimization is carried out by reducing the dimensions of the antenna components. After that, the DGS method is applied to widen the bandwidth. The initial design of the single-patch antenna before using the DGS method has a return loss value of -19.96 dB, VSWR 1.22, with a gain value of 3.812 dB and bandwidth 105.1 MHz. The simulation results of the antenna using DGS have a return loss value of -39.76 dB, VSWR of 1.02, with a gain value 3.16 dB and a bandwidth of 158.4 MHz. These results prove that the use of the DGS method can increase bandwidth.

Novel broadband circularly polarized pentagonal printed antenna design for wireless power transmission applications

<p>This paper provides a new conception for a microstrip patch antenna array that operates in a circularly polarized manner for wireless power transmission (WPT) at 2.45 GHz. The proposed conception combines four pentagonal patches and the defected ground structure (DGS) method. The antenna array with a dielectric constant of 4.4 and a tangential loss of 0.025 is printed on a FR4 where its thickness is about 1.58 mm. The developed design aims to optimize the antenna array performance. Th e main contribution, to the telecommunications and WPT fields, is to achieve a maximum energy transfer with low losses, while also ensuring adequate adaptation to the excitation port. To prove the effectiveness of this design, simulation results were obtai ned using computer simulation technology microwave studio (CST MWS) software and validated by another solver high - frequency structure simulator (HFSS). Simulation results are presented and compared with those obtained using existing conceptions in the lite rature. The proposed design has proven to be very effective in achieving the intended objectives, which makes this design very good for radiofrequency (RF) energy collection and its various applications to power a variety of devices without harming our pla net.</p>

Design of 5G MIMO 2x2 Broadband Antenna At 26 GHz Frequency Using Double U-Slot Method and Defected Ground Structure

The 5G technology is a telecommunications innovation that offers incredibly high-speed data transfer. It is expected to outperform its predecessors significantly. In utilizing 5G services, efficient devices are crucial, and solutions like Multiple Input Multiple Output (MIMO) systems play a key role. MIMO is an antenna system with numerous transmitting and receiving elements, enabling simultaneous transmission and reception. A 26 GHz frequency microstrip antenna is modified using a double U-slot, and the Defected Ground Structure (DGS) method is employed to reduce antenna coupling effects and enhance bandwidth. This antenna features a directional radiation pattern that focuses in a specific direction, thereby increasing efficiency. Prior to optimization, the return loss was at around -14.15 dB, VSWR was approximately 1.49 dB, and bandwidth was 0.65 GHz. After optimization, the return loss improved to between -27.06 and -28.09 dB, signifying performance enhancement. Despite a slight increase in VSWR to 1.08 to 1.09 dB, it remains within acceptable limits. The bandwidth increased to 1.06 to 1.13 GHz. These results indicate that optimization successfully boosted antenna performance, resulting in higher data transfer efficiency. This technology has the potential to revolutionize the telecommunications landscape with faster and more reliable services through advanced 5G networks.

Modified E-Shape Rectangular Microstrip Patch Antenna with DGS for Wireless Communication

A modified E-shape dual bands rectangular microstrip patch antenna for wireless applications is presented in this paper. An E-slot Microstrip patch antenna with a defective ground structure method has been proposed and getting two bands at 1.9 GHz and 2.89 GHz with S11 -10dB. Defective ground structures provide a maximum gain and low insertion loss i.e., a gain of 3.16 dB, voltage standing wave ratio less than 2, and insertion loss less than -10 dB for both bands. The size of the antenna is 46.83mm x 38.41mm x 1.676mm, which is compact in term of size. The dual band microstrip patch antenna exhibits low cost. The simulation's outcome closely resembles the actual printed antenna and applicable for WiMAX application. The antenna was designed using the Computer Simulation Technology (CST) software and printed on FR-4 substrate.

Truss bridge design with reclaimed steel elements by performing a stock‐constrained shape and topology optimisation

AbstractTo move up the circular economy hierarchy steel profiles should be reused instead of recycled. To efficiently utilise the limited availability of reclaimed steel elements in new structures, a different approach is required: form follows availability. This paper presents an algorithm for generating truss bridge designs using only reclaimed steel, which optimises material efficiency and avoids cut‐off waste. The algorithm does not require an initial design or a grid of possible positions like the commonly used ground structure method. Instead, it lets a truss geometry grow from start to end. The algorithm was developed using Python in Grasshopper, resulting in a user‐friendly parametric design process. By defining the width and span of a truss bridge and providing a stock of reclaimed elements, a solution cloud of locally optimal truss bridge designs in terms of capacity utilisation is generated, which comply to Eurocode provisions. An optimal design can be selected with given objectives, e.g. the lowest environmental impact. A case study showed that the developed growth method can lead to a truss with 63% less embodied carbon than conventionally designed new steel trusses and 17% less embodied carbon than optimised standard truss designs with retrofitted reclaimed steel elements.

New circularly polarized microstrip patch antenna array design for energy harvesting applications

This paper gives an essential contribution to the energy engineering topic, especially the energy harvesting field. Wireless power transmission (WPT) is one of the most widely used methods in this field recently to generate electricity in a clean way for the environment like the rectenna systems. The main component of the rectenna systems is the microstrip patch antenna (MPA). This is the main reason why this article proposes a novel conception of 1×4 circular polarized MPA array to operate in the industrial, scientific, and medical (ISM) band at the resonant frequency of 2.45 GHz for radio frequency energy harvesting (RFEH) systems. The basic MPA element is a square antenna using a center slot and V-slits at the four corners combined with a defected ground structure (DGS) method. This proposed conception is developed in order to improve the antenna’s performance to integrate with a rectifier circuit for the Rectenna systems which are the most used systems in RFEH. The simulation results obtained by CST MWS software and HFSS solver show that this novel design in this paper gives good performances in terms of the reflection coefficient, voltage standing wave ratio, axial ratio, directivity, and gain at 2.45 [GHz]. This developed MPA is suitable for various RFEH applications.

Explicit Topology Optimization Design of Stiffened Plate Structures Based on the Moving Morphable Component (MMC) Method

This paper proposes an explicit method for topology optimization of stiffened plate structures. The present work is devoted to simultaneously optimizing stiffeners’ shape, size and layout by seeking the optimal geometry parameters of a series of moving morphable components (MMC). The stiffeners with straight skeletons and the stiffeners with curved skeletons are considered to enhance the modeling and optimization capability of the current approach. All the stiffeners are represented under the Lagrangian-description framework in a fully explicit way, and the adaptive ground structure method, as well as dynamically updated plate/shell elements, is used to obtain optimized designs with more accurate analysis results. Compared with existing works, the proposed approach provides an explicit description of the structure. Thus, a stiffened plate structure with clear stiffener distribution and smooth geometric boundary can be obtained. Several numerical examples provided, including straight and curved stiffeners, hierarchical stiffeners, and a stiffened plate with a cutout, validate the effectiveness and applicability of the proposed approach.

Elliptical Patch Microstrip Antenna for Bluetooth/Wi-Fi Applications

In the wireless communication applications, widespread usage of microstrip patch antennas due to their advantages such as compactness, easy fabrication and low cost, is pushed forward researchers to develop desired antennas or improve the existing antennas to get desired one. But it is challenging to get desired antennas since microstrip patch antennas have some disadvantages such as low gain and narrow bandwidth. In this work, elliptical patch microstrip antenna is designed for Bluetooth/Wi-Fi applications. The antenna is designed in the form of slotted elliptical patch and defected ground structure method. Defected ground structure method is applied by using rectangular slots with different dimensions in this work. The proposed antenna is modelled using CST MWS software. Return loss, gain and directivity values are -16.45 dB, 1.82 dBi, and 5.81 dBi at 2.45 GHz, respectively. On the other hand, maximum directivity and gain values are 5.86 dBi and 2.06 dBi at 2.4 GHz, respectively. The bandwidth is 63.1 MHz (2.41 GHz – 2.48 GHz) at 2.45 GHz. According to the results, IEEE 802.11 b/g standards are supported by the designed antenna. So, it can be used for Bluetooth and Wi-Fi applications at 2.4 GHz.

Optimal vault problem – form finding through 2D convex program

This work puts forward a form finding problem of designing a least-volume vault that is a surface structure spanning over a plane region, which via pure compression transfers a vertically tracking load to the supporting boundary. Through a duality scheme, developed recently for the design of pre-stressed membranes, the optimal vault problem is reduced to a pair of mutually dual convex problems formulated on the 2D reference region. The vault constructed upon solutions of those problems is both of minimum volume and minimum compliance; analytical examples of optimal vaults are given. Through a measure-theoretic approach, such optimal vaults are proved to solve the Prager problem of designing a 3D structure that by compression carries a transmissible load. The ground structure method applied to the convex problems furnishes a pair of discrete, conic quadratic programs leading to optimal design of grid-shells. By adopting the member-adding adaptive technique, this pair is efficiently tackled numerically. The computer method is demonstrated on a number of examples where highly precise grid-shell approximations of optimal vaults are found.

Form-finding of tessellated tensegrity structures

Many large-scale tensegrity structures are formed by assembling repeating units; a tensegrity tower formed by stacking tensegrity prisms is one example. Tessellated tensegrity structures tend to feature a repeating topology, but the geometry and self-stress vary across the assembly. In this work we design tensegrity structures by imposing periodic boundary conditions on a single unit cell to enforce repetitive topology, geometry and self-stress. A tessellated tensegrity tower is designed by using a stiffness matrix form-finding technique in combination with nodal position constraints. Since the tessellated tensegrity is not globally in equilibrium, a transition structure is required to balance the tessellated tensegrity tower on one side and to connect to a fixed boundary on the other. The challenge in designing the transition structure is that both coordinates and residual forces are simultaneously predefined at specific nodes. In this paper, we propose an adapted stiffness form-finding method to design the transition structure as an alternative method to the conventional ground structure method.

Optimum topological bracing design of tall steel frames subjected to dynamic loading

In this paper, a frame structural topology optimization methodology for the generation of moment resisting braced frames for tall buildings, considering dynamic seismic loading, is presented. Real-world loading conditions along with standardized steel profiles of Euronorm are employed. In the literature, the studies that employ the ground structure topology optimization method are limited mostly to truss structures under static loading conditions. The dynamic response in the framework of structural topology optimization remains a challenging problem, especially when the ground structure method is used for deriving the structural system of tall buildings. The contribution of this study to the state of the art, relies on the implementation of the proposed methodology in the conceptual design phase of civil engineering frame structures, where both axial and flexural stiffness is considered. Direct time integration methods are used, to implement forced vibrations and real recorded earthquake data in the topology optimization procedure, resulting to novel layouts for lateral resisting systems of tall buildings. Aiming to aid the engineer to the final design phase, the response spectrum modal analysis is employed and the seismic loading is applied according to the Eurocode 8.

Ultra-Wideband Microstrip Bandpass Filter and Its Equivalent Circuit

Microstrip filters can be designed with various methods to obtain good performances, such as defected ground structure, open-ended slot, planar edge coupled, and split ring resonator with groundplane windowing. In this paper, the design of an ultra-wideband microstrip bandpass filter used the defected ground structure (DGS) method by adding a circular slot to the groundplane. The addition of the circular slot was carried out to improve the value of S parameter (return loss and insertion loss) from the initial filter design without a circular slot. In the simulation process, optimization was carried out by changing the value of filter component parameters such as patch length and thickness and circular slot width. The simulation results showed that the microstrip bandpass filter could pass frequencies in the range of 1.4 GHz to 5.7 GHz with the bandwidth response of 4.3 GHz. In addition, filter analysis could also be done with an equivalent circuit represented by lumped element components in the form of capacitors and inductors connected in series or parallel. The simulation results of the equivalent circuit had a wider bandwidth, which was able to pass frequencies in the range of 1.2 GHz to 6.1 GHz with a bandwidth response of 4.9 GHz.

Wideband Rectangular Patch Antenna With DGS For 5G Communications

A antenna with DGS and a rectangular radiator intended for Wideband applications with a working recurrence scope of 4GHz to 6.22GHz covering a transfer speed of 2.2GHz. Ground has been carved with a space in an occasional way which drove for the wideband transmission capacity. Fire resistant Glass epoxy substrate with a 50ω exciter is used to energize the antenna. Damaged Ground structure method has been executed to achieve the wideband of activity. The general component of the antenna is 25mm×10mm×1.6mm and is having wideband covering the C band recurrence from 4GHz to 6.22GHz covering a data transfer capacity of 2.2GHz with an arrival misfortune esteem not exactly - 10dB for whole transmission capacity. Economically accessible 3D test system software programming has been utilized to plan the antenna.

Simple and effective strategies to generate diverse designs for truss structures

Structural topology optimization plays an important role in obtaining conceptual designs in the preliminary design stage. However, traditional structural optimization methods can only generate one optimized design for the material distribution under certain constraints. The optimized structure could have some disadvantages, such as an unattractive appearance, difficulty in manufacturing, or high construction cost. Therefore, it is more practical to produce multiple designs that not only have high structural performance but also have substantially different forms from which the designer can choose. Two strategies were explored in this study for generating diverse truss structures, namely, the penalizing length method (PLM) and the modifying ground structure method (MGSM). Using the proposed PLM, it is possible to delete unneeded bars in the optimized structure, such as very slender bars, and the cross-sectional areas of the remaining bars will be automatically redistributed to ensure structural nodal stability. In addition, by generating overlapping potential bars in the ground structure, the structural instability problem caused by pin joints can be overcome. Two-dimensional and three-dimensional numerical examples were provided to indicate the effectiveness of the proposed methods. The numerical results showed that the proposed methodologies can generate diverse structures while maintaining structural performance.

Concurrent stringer topology and skin steered fiber pattern optimization for grid stiffened composite shell structures

The use of fiber steering to improve composite plate behavior for aerospace applications is only feasible if the steered laminates can be effectively combined with a stiffening grid. In this paper, a methodology is presented for concurrent optimization of stringers topology and fiber pattern of grid stiffened tow steered composite structures. A finite element formulation is obtained through symbolic integration for tow steered composite panels and is extended to analyze grid stiffened composite panels. One of the challenges in the topology optimization of grid stiffened panels is the separation of the stringers’ discretization from the skin discretization. The meshing of a stiffened panel is tedious and time-consuming, and changing the topology of stringers may require re-meshing of the complete design domain. Based on a weak formulation of the continuity requirements between skin and stringers, the Lagrange multiplier approach is proposed to circumvent this problem. This approach allows the meshes of stringers and skin to be independent. The accuracy of the resulting finite element solver is compared to that of a conformal mesh based solver. The optimization design variables are defined to describe both the topology of the stringers and the fiber patterns in each of the panel’s plies. The fiber pattern parametrization is based on Lagrangian interpolation of nodal based fiber angles. The fiber angle distribution is mapped on the centroids of the composite plate elements used for the FE analysis. In this approach, a manufacturing mesh is used to define the nodes for the design variables, i.e., the nodal fiber angles, controlling the fiber pattern in the skin. The ground structure method is used to optimize the topology of the stringers. The heights of the stringers in the ground structure are defined as the stringer design variables. Therefore, the overall design vector includes the fiber angles at the manufacturing mesh nodes for each ply and the stringers’ height in the ground structure. The method is tested using a buckling load optimization with constraints on manufacturing aspects, such as minimum tow turn radius. The Lagrange multiplier based coupling of stiffener and plate models was shown to be accurate and effective. The results of the concurrent optimization of stiffener grid and fiber patterns showed that steering does improve the behavior of stiffened plates.

Topological design of pentamode lattice metamaterials using a ground structure method

Pentamode metamaterials are a new class of artificially engineering three-dimensional lattice composites. There exist a few types of pentamode metamaterials that are dominated by ad hoc design motifs, while a systematic design approach is still missing. This paper will present an efficient topological optimization methodology to discover a series of novel pentamode lattice microarchitectures over a range of effective material properties. Firstly, the necessary and sufficient condition that is required for elasticity constants of pentamode micro lattices with at least elastically orthotropic symmetry is derived. Secondly, a general mathematical formulation for design optimization of such pentamode micro lattices is developed. Thirdly, a truss-based three-dimensional ground structure with geometrically orthotropic symmetry is generated, with geometric constraints to avoid intersection and overlap of truss bars within the ground structure. The genetic algorithm is then used to solve the topology optimization problem described by the ground structure. Finally, twenty-four pentamode lattices are designed to demonstrate the effectiveness of the proposed method.

Designing Franklin’s Microstrip Antenna with Defected Ground Structure at MMwave Frequency

The development of telecommunication technology is very rapid at this time has entered into 4G technology. Soon, the 5G technology has a fast data access speed of at least 1 Gbps. To support 5G technology is carried out in-depth research, especially in 5G antennas. This study aims to increase the bandwidth of Franklin's five array microstrip antennas using the DGS (Defected Ground Structure) method for 5G antenna applications at an operating frequency of 28 GHz. The research was conducted by doing rectangular defects in the ground field. This research produced an enhanced bandwidth by 1.707 GHz from 1.196 GHz without DGS (Defected Ground Structure) to 2.9 GHz with DGS (Defected Ground Structure). It means a bandwidth enhancement of 142.47%. At the same time, the design achieved a gain enhancement of 141.7 %. Franklin's microstrip antenna output with DGS (Defected Ground Structure) method from the research simulation results are the bandwidth of 2.9 GHz, reflection factor of -52.95 dB, and Gain 11.80 dB. In comparison, the results of antenna measurements that have been fabricated produce bandwidth of 2 GHz, reflection factor -27.72 dB on frequency 26.6 GHz. The deviation between the simulation and measurement may result in inaccuracies during the fabrication process.