Main Lobe Direction Research Articles

A Vortex Electromagnetic Wave Beam Control Method based on Amplitude-Modulated Concentric Circular Array

Abstract In order to enhance the design efficiency of vortex electromagnetic (EM) wave radar detection systems, a method for generating and controlling vortex EM waves based on amplitude-modulated concentric circular array (CCA) is proposed. This method allows for precise control of the vortex EM waves, ensuring accurate main lobe direction while effectively reducing sidelobes. Based on approximate orthogonal transformation, formulas for calculating the excitation amplitudes of each sub-circular array are derived and the time complexity of this method is negligible compared to search-based algorithms. Extensive simulation experiments are conducted and compared with the results obtained from the genetic algorithm (GA) approach, providing robust evidence of the effectiveness of this method(SLL < -30dB).

Special aspects of patch antennas synthesis using genetic algorithm

Microstrip-fed patch antenna synthesis can be performed using one of the numerous optimization algorithms, such as a genetic algorithm (GA). VBA or IronPython script engines implemented in modern CAD systems make it possible to implement GA. However, the capabilities of these languages for processing matrix data are limited. The use of a MATLAB environment script could combine the capabilities of MATLAB and CAD for electromagnetic modelling. It would make it possible to generate chromosomes of individuals of a given length, build antenna models in CAD that reflect the genetic code of individuals, process modelling results in MATLAB, carry out crossing over and mutations with a given probability for obtaining patch antennas that provide a user-specified value of the goal function. The primary purpose of this work is to propose a script in the MATLAB environment that allows complete automation of microstrip antennas' structural synthesis in MATLAB - CAD using GA, as well as to study GA selection methods and their influence on the results of this algorithm. As a result, a MATLAB script has been developed, combining the capabilities of electromagnetic modelling CAD and the MATLAB environment for processing matrix data for fully automated synthesis of the microstrip-fed patch antenna. It is shown that the proposed script randomly generates an initial population, creates a CAD model corresponding to each individual, determines the value of the goal function for each individual, performs crossing over and mutations, and then iteratively repeats the above actions until the GA convergence condition is satisfied. This paper highlights that the GA convergence speed depends on the selection method chosen before crossing over. Recommendations for choosing a selection method are formulated. The results of synthesizing a microstrip antenna with a frequency band 5.2 times greater than the frequency band of the reference antenna are presented. The presented script combines the capabilities of electromagnetic modelling CAD and MATLAB to fully automate the process of structural synthesis of microstrip antennas with a given frequency response and the main lobe direction of the radiation pattern.

Combining 77–81 GHz MIMO FMCW radar with frequency-steered antennas: a case study for 3D target localization

Abstract In this paper, we introduce a compact 6 × 8 channel multiple-input multiple-output frequency-modulated continuous-wave radar system capable of determining the three-dimensional positions of targets despite utilizing a linear virtual array. The compact system, containing two cascaded radar transceiver ICs, has 48 virtual channels. We conduct a direction of arrival estimation with these virtual channels to determine the azimuth angle. To overcome the spatial limitation of the linear array, we use frequency-steered transmit antennas, which vary their main lobe direction during the frequency chirp, allowing the elevation angle to be determined by using a sliding window fast Fourier transform algorithm. In this study, we present the system’s concept along with the associated signal processing. By taking measurements in different scenarios, each with differently placed corner reflectors, we investigate the capability of the system to separate adjacent targets concerning range, azimuth, and elevation. These measurements are additionally employed to point out the design trade-offs inherent to the system.

Time-range FDA beampattern characteristics

Current literature show that frequency diverse arrays (FDAs) are able of producing range–angle-dependent and time-variant transmit beampatterns, but the resulting time and range dependencies and their characteristics are still not well understood. This paper examines the FDA transmission model with an emphasis on analyzing the beam auto-scanning characteristics and the equivalence with the MIMO beampatterns taking into account their time-range relationship. We present the FDA instantaneous transmit beampattern, describing the auto-scanning capability of the FDA transmit beams. The scan speed, scan volume, and initial mainlobe direction of the beams are also analyzed. In addition, the equivalent conditions for the FDA integral transmit beampattern and the multiple-input multiple-output (MIMO) beampattern are investigated. Various numerical simulations illustrate the auto-scanning property of the FDA beampattern and the proposed equivalent relationship with the MIMO beampattern, providing a foundation for a better understanding and application of the FDA transmit beam.

Design of half circular wideband antenna for ship radar

The research aims to design a wideband antenna for the ship's radar. The ship's radar works on the S-Band range whose wavelengths range from 8 to 15 cm with a frequency of 2-4 GHz, This antenna design uses a new approach involving the use of Defected Ground Structure (DGS) and Defected Microstrip Structure (DMS), which builds on the initial theory. The results of the study obtained a bandwidth value of 1.6 GHz, an impedance antenna value of 49.7 ohms, with a total efficiency of -0.3356 a working frequency range ranging from 1.74 GHz to 3.3 GHz. The radiation pattern obtained the main lobe magnitude value of 3.85 dBi, Main lobe direction of 162.0 deg, angular width (3dB) of 76.7 deg, and side lobe level of -1.1 dB. From the results of working frequency, it is found that the antenna can be used for airborne warning & control (AWACS), remote sensing, WiFi, Bluetooth, mobile communication, XM radio, airport surveillance radar (ASR), radioastronomy, wireless LAN, ZigBee, missile guidance.

PCB Rogowski Coil sensor by using Saw blade pattern for arcing fault detection

Rogowski is a special current transformer and has been categorised as a low-power stand-alone current sensor. This sensor is designed by using a Saw blade pattern with 50 turns and 100 turns. This number of turns will impact the increment of the sensitivity of the sensor. Rogowski coil is used for measuring the alternating current (AC) and high-speed current pulses. The PCB Rogowski Coil will detect the arcing fault that design with AutoCAD software after that import to CST software. An arc is created when the electrical current jumps the gap between two conductive materials. The most common causes of arcs include worn contacts in electrical equipment, damage to insulation, break in a cable and loose connections. In order to reduce the arc fault risk, the arc fault interrupter (AFI) technology and arc fault detectors (AFD) have been developed. However, these devices are most suitable for domestic application or low voltage (LV). This paper proposed a simulation using AutoCAD and CST software to design a Rogowski coil and the Rogowski Coil sensor will be tested by using CST software in terms of radiation pattern. The biggest radiation pattern in red colour is the saw blade pattern in 100 turns at 2 KHz frequency, the radiation pattern covering entire sensor area compared with other radiation patterns with other frequency. The main lobe magnitude for 2 KHz frequency is 46.8 dB, main lobe direction is 180 deg, angular width is 153.4 deg and the side lobe level is zero. This is the best number of turn and frequency compared to 50 turn saw blade sensor.

A reconfigurable graphene patch antenna inverse design at terahertz frequencies

This article investigates the inverse design of a reconfigurable multi-band patch antenna based on graphene for terahertz applications to operate frequency range (2–5THz). In the first step, this article evaluates the dependence of the antenna radiation characteristics on its geometric parameters and the graphene properties. The simulation results show that it is possible to achieve up to 8.8 dB gain, 13 frequency bands, and 360^circ beam steering. Then and due to the complexity of the design of graphene antenna, a deep neural network (DNN) is used to predict the antenna parameters by given inputs like desired realized gain, main lobe direction, half power beam width, and return loss in each resonance frequency. The trained DNN model predicts almost with 93% accuracy and 3% mean square error in the shortest time. Then, this network was used to design five-band and three-band antennas, and it has been shown that the desired antenna parameters are achieved with negligible errors. Therefore, the proposed antenna finds many potential applications in the THz frequency band.

Hybrid Mode Reconfigurable Antenna with V-Shaped Extrudes for Cognitive Radio Applications

As the same device may be used for various types of applications, antennas must have the capacity to perform multiple functions. Reconfiguring the polarization, operational frequency, and radiation pattern can create an outcome of multi-functionality. A hybrid, frequency- and pattern-reconfigurable antenna with two V-shaped extrudes in a patch is proposed. To increase the bandwidth of the proposed antenna, the defected ground structure (DGS) phenomenon is presented, which is significant in the bandwidth of 3200 MHz from 2.7 GHz to 5.9 GHz, providing a gain of 3.5 dB. For this design, an FR-4 material was chosen as the substrate, and CST software was used for simulation. Using two p-i-n diodes, the projected antenna illustrates switching for multi-frequency bands such as 1.5, 2.6, 3.2, 5.1, and 8.1 GHz, with a constant radiation pattern and a main lobe direction of 155 degrees. It has C-band, WLAN, cognitive radio (CR), and Bluetooth applications. The proposed antenna displays radiation pattern switching at 3.5 GHz, showing variation between 7°, 158°, 173°, and 175°, and at 4 GHz, it demonstrates switching between 11°, 15°, 165°, and 344°, which defines the hybrid reconfiguration.

A Multisurrogate-Assisted Optimization Framework for SSPP-Based mmWave Array Antenna

Spoof surface plasmon polariton (SSPP) transmission lines are frequently used to excite millimeter-wave (mmWave) antenna arrays due to high field confinement and easy integration with planar structures. However, the design of the SSPP-based array antennas requires significant efforts because of multiple specifications, the high cost of electromagnetic (EM) evaluations, and a large number of design parameters. This article proposes a multisurrogate-assisted optimization framework for the efficient design of SSPP-based mmWave array antennas. The framework has three stages. In each stage, a surrogate is proposed to solve a specific task. The first stage is to find the initial values of four key design parameters using artificial neural network (ANN)-based surrogate model optimization. The second stage focuses on the optimization of sidelobe level based on another ANN surrogate model. The third stage is a beamforming-focused optimization procedure using the space mapping technique with an improved array factor formula as a surrogate. An mmWave SSPP-based array antenna with 16 circular patches at a central frequency of 28 GHz is successfully designed using the proposed framework. The antenna is also redesigned for five sets of main lobe directions and null locations at 24 GHz. All antennas are verified using full-wave EM simulations.

Main lobe interference suppression method of Skywave OTHR based on fast-time STAP

For the sky-wave over-the-horizon radar (OTHR), how to effectively suppress the radio frequency interference (RFI)from the main-lobe direction is a problem. To solve this problem, this paper proposes a new space-fast time adaptive processing (fast-time STAP) which merges the matched filter coefficients used for pulse compression and the time steering vector of fast-time STAP. To compare with conventional methods, the method improves the match between the space-time steering vector of fast-time STAP and the real target signal, while the RFI and the noise from RFI are effectively suppressed by the interference-plus-noise covariance matrix which is composed of raw data. At the same time, the signal-to-noise ratio is improved. Compared with the traditional method, this method can be better applied to practical engineering. The results of computer simulation and experiments with real radar data verify the effectiveness of the proposed method.

Optically Remote Control of Miniaturized 3D Reconfigurable CRLH Printed Self-Powered MIMO Antenna Array for 5G Applications.

A novel design of a reconfigurable MIMO antenna array of a 3D geometry-based solar cell integration that is operating at sub-6 GHz for self-power applications in a 5G modern wireless communication network. The proposed antenna array provides three main frequency bands around 3.6 GHz, 3.9 GHz, and 4.9 GHz, with excellent matching impedance of S11 ≤ -10 dB. The proposed MIMO array is constructed from four antenna elements arranged on a cubical structure to provide a low mutual coupling, below -20 dB, over all frequency bands of interest. Each antenna element is excited with a coplanar waveguide (CPW). The proposed radiation patterns are controlled with two optical switches of Light Dependent Resistors (LDRs). The proposed antenna array is fabricated and tested experimentally in terms of S-parameters, gain and radiation patterns. The maximum gain is found to be 3.6 dBi, 6.9 dBi, and 3.5 dBi at 3.6 GHz, 3.9 GHz, and 4.9 GHz, respectively. It is realized that the proposed array realizes a significant beam forming by splitting the antenna beam and changing the main lobe direction at 3.9 GHz after changing LDR switching statuses. Such an antenna array is found to be very applicable for femtocell wireless communication networks in the 5G systems.

Optically remote‐controlled miniaturized 3D reconfigurable CRLH‐printed MIMO antenna array for 5G applications

AbstractA reconfigurable MIMO antenna array of a three‐dimensional geometry that is operating at sub‐6 GHz for 5G applications. The proposed antenna array provides a wideband with excellent matching impedance, S11 ≤ −10 dB, from 3.1 to 5.75 GHz. The proposed MIMO array is constructed from four antenna elements arranged on a cubical structure to provide a low mutual coupling, below −20 dB, over all frequency bands of interest. Each antenna element is excited with a coplanar waveguide. The proposed radiation patterns are controlled with two optical switches of light‐dependent resistors (LDRs). The antenna array is tested in terms of S‐parameters and radiation patterns. The maximum gain is found to be 3.6, 6.9, and 3.5 dBi at 3.6, 3.9, and 4.9 GHz, respectively. It is realized that the proposed array realizes a significant beam forming by splitting the antenna beam and changing the main lobe direction at 3.9 GHz after changing LDR switching statuses.

Beamforming MIMO Array Antenna for 5G-Millimeter-Wave Application

The high gain, high speed/data rate, high capacity, and beamforming antennas are required for the present generation of mobile and wireless applications to satisfy the exponentially growing demands of the users. This paper presents low mutual coupling multiple input-multiple output (MIMO) array antenna for millimetre-wave (mmw) application. The MIMO-array beamforming antenna with 2:1 VSWR band is proposed for 28.0 GHz and covers 27.04–28.35 GHz frequency band, which is suitable for mm-wave n261 5G-band which cover the frequency range from 27.5–28.35 GHz. It consists of $$2\times 12$$ antenna array elements and the prototype is designed on low loss Rogers Duroid 5880 substrate of size $$51.45 \times 36.87\,{\text{mm}}^2.$$ The beamforming MIMO antenna covers $$\pm \,20^{0}$$ main lobe directions. The mutual coupling at the MIMO-array ports is less than 28.0 dB. The radiation efficiency and the gain in the presented band are more than 93.0% and more than 13.99 dBi. The ECC in the presented frequency band is $$\le 10^{-4}$$ , which is one of the advantages of the proposed design. The design covers indoor and outdoor Gaussian applications, and has 1.31 GHz TARC active bandwidth. It has 4.65% simulated and 4.73% measured fractional bandwidths.

A Novel Realistic Approach of Adaptive Beamforming Based on Deep Neural Networks

A new deep neural network (NN) approach applied to antenna array adaptive beamforming is presented in this article. A recurrent NN (RNN) based on the gated recurrent unit (GRU) architecture is used as a beamformer in order to produce proper complex weights for the feeding of the antenna array. The proposed RNN utilizes four hidden GRU layers and one extra layer for linear transformation. The produced weights are subsequently compared with respective weights derived by a null steering beamforming (NSB) technique in order to measure the accuracy of the RNN. The RNN training is performed by using a large dataset derived from an NSB technique applied to a realistic microstrip linear antenna array, in order to consider real-world effects, such as the nonisotropic radiation pattern of an array element and the mutual coupling between the array elements. The RNN performance is examined by using the root-mean-square error metric, whereas its beamforming performance is evaluated by estimating the mean value and the standard deviation of the divergences of the main lobe and nulls directions from their respective desired directions. A comparison between various NN structures and an overall study of the proposed RNN-based beamformer are also presented.

Metamaterial-inspired quintuple band printed patch antenna for dense communication networks

A compact 15 mm × 15 mm multi-band metamaterial-inspiredprinted antenna, composed of a simple microstrip antenna and a metamaterial superstate, is developed to accommodate nowadays advanced wireless communication devices and networks, where multi-functional tasks are simultaneously performed in different frequency ranges efficiently. A quintuple homocentric circular split ring resonator is explicitly designed as a band enhancer metamaterial superstate. The metamaterial geometry and orientation associated with the antenna location and radiating are optimized for the greatest consequence, where the resonances electrically and magnetically couple with the antenna radiation, generating quintuple bands in the X band: 8–12 GHz. The main lobe directions indicate an excellent directional propagation. This metamaterial-inspired antenna was designed and fabricated using a low cost commercial FR4 substrate offering a good cost margin for potential mass production. Four of five bands have a gain greater than 6dBi, which can be improved by using low-loss substrate. The measured and simulated results are in good agreement.

Real-time programmable coding metasurface antenna for multibeam switching and scanning

Novel electromagnetic wave modulation by programmable dynamic metasurface promotes the device design freedom, while multibeam antennas have sparked tremendous interest in wireless communications. A programmable coding antenna based on active metasurface elements (AMSEs) is proposed in this study, allowing scanning and state switching of multiple beams in real time. To obtain the planar array phase distribution in quick response, the aperture field superposition and discretization procedures are investigated. Without the need for a massive algorithm or elaborate design, this electronically controlled antenna with integrated radiation and phase-shift functions can flexibly manipulate the scattering state of multiple beams under field-programmable gate array (FPGA) control. Simulation and experimental results show that the multiple directional beams dynamically generated in the metasurface upper half space have good radiation performance, with the main lobe directions closely matching the predesigned angles. This metasurface antenna has great potential for future applications in multitarget radar, satellite navigation, and reconfigurable intelligent metasurfaces.

Beamforming in the Generation of Range-Time-Dependent Orbital Angular Momentum Based on the Circular Frequency Diverse Array

In this article, we combine the frequency diverse array (FDA) with the vortex electromagnetic wave theory and propose a beamforming method in the generation of range-time-dependent orbital angular momentum (OAM) based on the circular FDA (CFDA). First, we establish a CFDA-based OAM-generating structure, based on which the feasibility of CFDA to generate OAM is verified. Then, we analyze the range-time-dependent characteristics of the generated OAM. Furthermore, concerning the field of radar imaging and target detection, we investigate beamforming with the CFDA-based OAM. Two main issues are addressed: beam collimation and sidelobe suppression. Therefore, according to the derived angular offset between the mainlobe direction and the beam axis, we steer the beam at the target through the phase shifter. Moreover, the sidelobe is suppressed by selecting an appropriate antenna pattern. Finally, based on the analysis of beam collimation and sidelobe suppression, we establish the CFDA configuration for beamforming. Numerical examples and simulations show the superiority of the proposed beamforming method.

Asymmetric Endfire Frequency Scanning Tapered Slot Antenna With Spoof Surface Plasmon Polaritons

An endfire frequency scanning tapered slot antenna (FSTSA) is proposed and investigated. The proposed FSTSA is a two-conductor structure with a gradient slots array etched only on one of two inner edges in the FSTAS. The asymmetrical inner edges enable the antenna to excite two modes with different phase constants simultaneously along the two inner edges. Due to dispersion characteristics of spoof surface plasmon polaritons (SSPPs), the phase difference between the EM waves along the two conductors changes versus frequencies, which enables the main lobe of the FSTSA to scan through the endfire direction. An analysis model is conceived to provide insights into the design, which accurately predicts main lobe directions and initial values of the proposed antenna. The proposed antenna is fabricated, and the measured results show that the main lobe of the antenna scans from −15° to 14° (endfire direction at 0°) from 6.60 to 7.70 GHz, with the scanning rate of 26.4°/GHz. This antenna could be suitable for radar, plane integrated communication system, and certain other beam-scanning applications.

Improved Beamforming in 3D Space Applied to Realistic Planar Antenna Arrays by Using the Embedded Element Patterns

Most of beamforming methods rely on the proper estimation of the steering vectors of the incoming signals in order to calculate appropriate array feeding weights. However, this estimation is often performed on a theoretical basis, since most methods assume that the array elements radiate like isotropic sources and consider only the phase differences between them due to their different spatial positions. This is a rough estimation as it ignores both the non-isotropic radiation pattern of the array elements and the mutual coupling between them. To overcome these limitations, we use a different approach for the construction of steering vectors based on the embedded patterns of the array elements, extracted through full-wave analysis. This approach is used in this paper to modify two well-known beamforming methods, namely the null steering beamforming and the minimum variance distortionless response method. Both modified methods are applied to a realistic model of a microstrip planar antenna array, and thus, both the azimuth and polar angles of the main lobe and nulls directions are controlled (beamforming in 3D space). Extensive statistical analyses are performed by implementing several scenarios of escalating difficulty, in order to examine the performance and temporal response of the modified beamforming methods in comparison to the respective conventional methods and also in comparison to beamforming methods based on evolutionary techniques.

Design and Analysis of Microstrip Patch Antenna properties with Split-Ring Resonator Metamaterial as Superstrate at mmWave Frequency

The Microstrip Patch antenna which is considered as low profile and easy to fabricate antenna incorporates drawbacks that include low gain and bandwidth. Using Metamaterials superstrate both bandwidth and the gain of patch antenna can be enhanced. This paper basically includes the study characteristics of rectangular patch antenna that is fed by microstrip line, with metamaterial as the two layers of superstrate is carried out at mmWave frequency ie 24GHz. The rectangular patch antenna is designed, that resonate at 24GHz, with copper as the radiating material put on Rogger 5880 substrate of 0.5mm thickness. The substrate dimension is taken to be 15mmx 15mm. The metamaterial structure exhibits negative permittivity and permeability at the same frequency as that of rectangular patch antenna ie at 24GHz. The substrate used for SRR structure design is Rogger 5880 of thickness 0.2mm. The unit cell dimension is 1.6mm x 1.6mm and the superstrate layer consists of a 9x9 SRR structure. Rectangular Patch characteristics are studied by placing the single layer and double layer of the superstrate at various distances (in mm). It is observed that placing a double superstrate layer with a gap of 1mm between them was placed at a distance of 1mm from the resonating rectangular patch antenna, making the antenna exhibit a multi-band feature along with an increase in the antenna gain. The Rectangular Patch antenna, SRR structure simulation is carried out in the CST simulation tool. Simulation results show that SRR characteristics are satisfied at 24GHz ie it behaves like a double negative structure and was verified using Matlab. The antenna shows multi-band resonance behavior at 24.033GHz, 25.36GHz, 25.285 GHz, 26.27 GHz when a double layer of 9x9 Split Ring Resonator is added above the radiating element. The gain offered by a single patch was 7.57dB and with the superstrate layer, the gain obtained was 9.01dB. The polarization component along the main lobe direction shows the cross-polarization component is found to be -85dB. The analysis of antenna with and without superstrate shows that there is improvement in gain and the multiband resonance can be achieved.