Circular Antenna Array Research Articles

Sidelobe level minimization for uniform circular smart antenna array using cultural algorithm

Cultural algorithm (CA) is a new evolutionary program inspired by sociology and archaeology theories that assisting formulating cultural evaluation. Its use to solve optimization problems. This paper analyzed the beamforming of a uniform circular antenna array (UCAA) via using the CA algorithm. The sidelobe level (SLL) is minimized by adjusting the appropriate weight for each element. In addition, the optimal beam pattern is achieved by using CA for UCAA, which means that the main beam is steering to the desired user, while the nulls represent the interference signals. The excitation amplitude is supposed to be constant while the elements are assumed isotropic. The circular array number elements and the interspacing distance between them are setting as optimization parameters. The simulation results show that the CA rationally reacts to the changing environments, and it is valuable for SLL reduction. A −25 dB of relative SLL is achieved under beam scanning (0º) and (15º), respectively.

Performance evaluation of Non-Uniform circular antenna array using integrated harmony search with Differential Evolution based Naked Mole Rat algorithm

In many wireless applications, circular antenna arrays are commonly used but managing the lower side lobe with high directivity is still challenging. Many typical methods could be used to synthesize the array in real time but lag behind to retain high directivity and the low sidelobe level. This study formulates an optimization problem to obtain the desired main lobe direction, suppress the subsidiary lobe, and maximizes the directivity. A modified optimization algorithm is proposed called Integrated Harmony Search with Differential Evolution based Naked Mole Rat Algorithm (IHDN) to rapidly and reliably refine control parameters. Simulations are performed, and results are compared to other traditional algorithms. The findings show that the proposed algorithm results in excellent side lobe minimization with good directivity. The size analysis indicates that good directivity values with low sidelobe levels can be obtained for a smaller number of antenna elements.

Design of Wideband Antenna Array for WiMax Application

Abstract: The evolution of wireless communication system has led path for innovative antenna design specifically in wideband antenna for WiMax application. In this paper design and simulation of microstrip wideband circular patch antenna array operating between 2GHz to 4Ghz is presented. The circular patch antenna is designed to operate at 3GHz line feed and the ground is itched to achieve required wideband characteristics. The simulation is carried out in EM Flow solver, High Frequency Structure Simulator software. For a single patch antenna, the return loss, lesser than -10dB throughout the bandwidth. Later an antenna array is operating between 2GHz to 4GHz frequency is designed and simulated. The return loss is lesser than -12dBi throughout the band and a peak gain is 14.7dBi. Keywords: Microstrip Patch Antenna (MPA), High Frequency Structure Simulator (HFSS).

Mutual coupling reduction using plane spiral orbital angular momentum electromagnetic wave

ABSTRACT Circular phased array antennas with a quasi-omnidirectional pattern to generate transverse orbital angular momentum (OAM) waves with modes and are designed at the frequency of 4 GHz. Proposed antennas consist of eight substrates integrated waveguide (SIW) H-plane horn elements and microstrip corporate feeding networks. Experimental results show that the mutual coupling between array antennas can be reduced by employing transverse OAM waves with different modes.

Synthesis of Non-Uniform Circular Antenna Array for Low Side Lobe Level and High Directivity Using Self-Adaptive Cuckoo Search Algorithm

Synthesis of Non-Uniform Circular Antenna Array for Low Side Lobe Level and High Directivity Using Self-Adaptive Cuckoo Search Algorithm

Vortex Beam Optimization Design of Concentric Uniform Circular Array Antenna with Improved Array Factor

In this paper, an improved array factor of the concentric uniform circular array (CUCA) antenna is proposed for the orbital angular momentum (OAM) vortex beam optimization design. From the perspective of the radiation pattern’s power conservation principle, a correction factor is introduced to the conventional array factor of CUCA. Then, based on the improved array factor, by adjusting the rings’ radii parameters of the CUCA, we optimize the vortex beam’s sidelobe level through the generic algorithm (GA). Two different CUCA antenna model are calculated as examples to further illustrate the effectiveness of the improved array factor. Subsequently, an electromagnetic simulation model of two rings CUCA antenna is built at C band for generating low sidelobe vortex beam carrying OAM mode. The electromagnetic simulation model of the designed CUCA antenna is also fabricated and measured. The corresponding antenna far-field vortex beam radiation pattern and near-field vortex wave electric field distributions are measured. The simulation results and the measurement results are in good agreement. The proposed designs of antenna and OAM vortex beam regulation are expected to be used for 5G and 6G communications applications

An artificial magnetic conductor loaded, polarization reconfigurable circular patch array antenna

A low-profile polarization reconfigurable circular patch array antenna is presented in this article. It is illustrated that by introducing two reverse arrangement diodes in every concentric ring patch, the direction of current on the surface of the antenna can be switched flexibly, by controlling the operating states of the diodes. Thus, the polarization of the proposed array antenna can be switched in either left hand circularly polarization or right hand circularly polarization. The introductions of artificial magnetic conductor decrease the profile of the proposed antenna. The performances of the proposed antenna were validated by the prototype processing. The measurement results show that the proposed antenna has a 16.3% impedance bandwidth and a 6% 3 dB axial ratio bandwidth. It exhibits a 9.5 dB broadside gain in the CP band. The profile of the proposed antenna is 46.9% lower than the previous design. The measured results are in good agreement with the simulation results. And it has potential applications in S-band satellite communications.

Re‐Evaluation of a Dual‐Feed Linear Polarized 2‐by‐2 Circular Patch Array Antenna for 60‐GHz‐Band Digital Beamforming Applications

In this letter, re‐evaluation results of a 60‐GHz‐band digital beamforming antenna using a dual‐feed linear polarized 2 × 2 circular patch array antenna is reported. The extension from our previous report is providing new measurement data under the condition of all intermediate frequency (IF) signal usage by re‐fabrication, although we reported imperfect measurement results using the IF signals only 5 ch out of 8 ch in the previous report due to the fabrication error. A low temperature solder paste was newly used to prevent the warp of the multilayered substrate. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

On the Use of Machine Learning for Direction Finding with Circular Monopole Antenna Arrays

The training of a deep neural network for amplitude-only (AO) direction finding (DF) is presented. Four circular arrays with 3-, 4-, 6-, and 8-element uniformly distributed monopoles are considered. The impact of a center-placed metallic post on the performance of the arrays in conjunction with the utilized DF algorithm is investigated. The 1 GHz resonant arrays are first designed in Altair FEKO and voltages produced at the terminals of the antennas from incident plane waves are determined. These signals, at a signal-to-noise ratio of 20 dB, are then used to train the neural network for AO-DF. The best performing configuration, the 8-element array, has 1.8° root mean squared error and 1.33° average error across the 360° field of view. While the 3- and 4-element arrays without a post performed poorly, all other considered topologies yielded an average error less than 4°. These results allow system designers to make educated decisions in the context of a cost vs accuracy tradeoff.

A Novel Ultrawideband Gear-Shaped Dielectric Ring Resonator Antenna

In this study, a novel ultrawideband (UWB) dielectric ring resonator (DRR) antenna has been proposed. DRR antennas include a single monopole antenna in the center of a ground plane and a dielectric with a symmetric structure around the monopole. This structure will lead to ultrawide band antenna. However, it is still possible to enhance the antenna bandwidth. In this study, we combine the DRR structure with an array antenna. The proposed antenna includes a circular array of four triangle resonators, which is rotated around the center of the triangle base to form a gear-shaped ring resonator antenna. In this design, characteristics of all these antennas are combined to enhance the antenna bandwidth including triangular dielectric resonator, circular array antenna, dielectric ring resonator structure, and a quarter-wave electric monopole. Triangular dielectric resonator antennas are wideband and in small size. Ring resonator antennas are inherently ultrawideband. Quarter-wave electric monopole and circular array structure can also enhance antenna bandwidth. This novel shape of the DRR antenna possesses the wider impedance bandwidth compared to similar works. Impedance bandwidth is 150% (5.2–36.1 GHz), and the bandwidth ratio is 1 : 6.9, which is much greater than earlier reports.

Generation of rotational orbital angular momentum beams in the radio frequency based on an optical-controlled circular antenna array.

The orbital angular momentum (OAM) has been widely used in the wireless short-range communication system, but for long-distance communication, the huge difficulty of beam receiving is a great challenge. In this paper, to overcome this challenge, a generation system of radio-frequency rotational orbital angular momentum (RF-ROAM) beams based on an optical-controlled circular antenna array (CAA) is proposed. The ROAM beam is an OAM beam rotating at a certain speed around the beam axis. According to the rotational Doppler effect, the rotation of the OAM beam will induce a frequency shift proportional to the OAM mode and the rotation speed. Thereby, by rotating an OAM beam at a fixed speed scheduled in advance in the transmitting end, the beam can be mode-distinguished by just detecting the frequency shift without receiving the whole wavefront vertical to the beam axis in the receiving end. This provides a partial reception scheme for the OAM-based wireless communication system. The generation system of RF-ROAM beams is proposed and constructed, and the proof-of-concept experiment is performed. In the system, the optical-controlled CAA is constructed to generate the general RF-OAM beam, the optical signal processor (OSP) is employed to control the phase shifts to further control the OAM mode, and the signal with time-varying phase is generated as the rotation factor to control the rotation speed. In the experiment, the RF-ROAM beams with different mode and mode combination are generated and successfully measured by detecting the frequency shift of the signal received in a fixed point.

Synthesis of Cosecant-Squared Beam Patterns of Concentric Circular Antenna Array in a Range of Azimuth Plane Using Evolutionary Algorithm

Synthesis of Cosecant-Squared Beam Patterns of Concentric Circular Antenna Array in a Range of Azimuth Plane Using Evolutionary Algorithm

Phase Compensation Technique for Effective Heat Focusing in Microwave Hyperthermia Systems

In this paper, effective electromagnetic (EM) focusing achieved with a phase compensation technique for microwave hyperthermia systems is proposed. To treat tumor cells positioned deep inside a human female breast, EM energy must be properly focused on the target area. A circular antenna array for microwave hyperthermia allows EM energy to concentrate on a specific target inside the breast tumor. Depending on the cancerous cell conditions in the breast, the input phases of each antenna are calculated for single and multiple tumor cell locations. In the case of multifocal breast cancer, sub-array beam focusing via the phase compensation technique is presented to enhance the ability of EM energy to concentrate on multiple targets while minimizing damage to normal cells. To demonstrate the thermal treatment effects on single and multiple tumor locations, the accumulation of the specific absorption rate (SAR) parameter and temperature changes were verified using both simulated and experimental results.

An improved biogeography‐based optimization approach for beam pattern optimizations of linear and circular antenna arrays

AbstractAntenna array makes an increasingly valuable contribution to various fields of communications. The beam pattern synthesis is one of the significant properties of antenna array. In this article, suppressing the maximum sidelobe levels (SLLs) of different antenna arrays is our main objective. Specifically, we first formulate the beam pattern optimization problems of the linear antenna array (LAA) and circular antenna array (CAA), respectively, and propose an improved biogeography‐based optimization (IBBO) approach to tackle the issue. IBBO introduces the hybrid migration and hybrid mutation operators by adopting several improved factors to strengthen the effect of conventional biogeography‐based optimization (BBO) algorithm. Emulate experiments are built to evaluate the performance of the IBBO for dealing with the formulated antenna array beam pattern optimization problems comprehensively.

Design of Higher-Order Circular Array Antenna with Multiple Patch Elements Based on Angular Momentum

This paper presents the generation of modes of angular momentum of the orbital type using a proposed array antenna fed with Rotman lens of multiple layers of compact size. The gain of orbital angular momentum is enhanced by the proposed microstrip antenna, which is a circular array antenna with nine elements fed with Rotman lens utilizing the patch element of high gain. Antenna gain can be enhanced in an effective manner; the patch element is attached with two slots loaded in a stacked patch. The circular array when employing the feeding network with Rotman lens causes excitation of different input ports, which produces carrying beams of orbital angular momentum with mode numbers m = 0, m = ±1, m = ±2, m = ±3, and m = ±4. A phase shift of 160 deg is achieved on the output ports in the adjacent position for meeting the requirement of the phase of orbital angular momentum modes of m = ±4. The detection angle of the ports of the beam and array is adjusted by modifying the Rotman lens for achieving the uniform distribution of amplitude on the output ports of the antenna. Therefore, effective improvement is observed in the radiation pattern of the orbital angular momentum beams, which obtains equal amplitude in all the output ports. The fabrication of a prototype antenna of C band is done, and measurements are performed. Simulated results match the measured results, indicating that generation of orbital angular momentum is done by the antenna proposed in this paper, which can be used in communication systems based on orbital angular momentum.

Mutual Coupling Effect on Arbitrarily Oriented VLF Circular Antenna Array in Ionospheric Plasma

Mutual coupling between the space-borne antenna has an essential impact on the communication characteristics of a wireless link to submerged submarines. In this article, the mutual coupling between antennas of a circular array in an anisotropic plasma over a very low-frequency (VLF: 3–30 kHz) range is investigated. An expansion of the currents into phase modes enables us to develop an efficient method to analyze the mutual coupling between antennas. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> -coupled integral equations for antennas of an array are first derived with full consideration of the mutual coupling effect. By making use of the phase modes combined with the method of moment (MoM), the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> -coupled integral equations are decomposed into independent ones and solved for each phase mode. Computations and discussions show that the self and mutual impedances of antennas are increased with the geomagnetic field tilt angle. Moreover, the mutual impedance is decreased with the increasing electrical separation, thereby indicating that the mutual coupling effect is weakened as the separation increases. The accuracy of the proposed method is verified by comparing the computed results with experiments and simulation using commercial electromagnetics software FEKO.

Adaptive Array Antenna in Ground Station Control System for Massive LEO CubeSat Constellation Tracking

Since Low Earth Orbit has become a popular orbit to place satellites, CubeSat constellation tracking is challenging. The higher capacity and capability of a new Ground Station tracking system are in demand and this motivates researchers to come out with a solution to mitigate the traditional Ground Station degradation performance. This paper discusses the implementation of the Least Mean Square algorithm to the Adaptive Array Antenna for the Ground Station tracking system application. The simulation results show the main beam pattern’s capability to perform instantaneous tracking and steering towards the targeted CubeSat while suppressing the side lobes towards the other interfering CubeSats when massive CubeSats constellations take place. Planar and circular array antennas are analyzed by setting the optimum weighting factors to be adapted. Three scenarios of CubeSats constellations are simulated. The Adaptive Array Antenna’s performance for each scenario is analyzed based on the beam width characteristics and the Signal-to-Interference Ratio of the beam pattern. The number of CubeSats tracked by the Adaptive Array Antenna and the system’s capability to perform fast tracking as the number of antenna array elements is also discussed in this paper. Finally, solutions to mitigate the Least Mean Square algorithm’s limitation to perform fast tracking when massive interferer CubeSats are nearby are proposed.

Generating orbital angular momentum based on circular antenna array with filtering characteristic

The circular antenna array with filtering characteristic for orbital angular momentum's (OAM) generation is proposed in the paper. An antenna unit consisting of one patch with V-shape slots, two shorting pins and defected ground structures is firstly designed, simulated, and measured. And the simulated and experimental results demonstrate that the designed antenna has a great filtering respond with a flat gain about 5 dB from 5.1 to 5.5 GHz. The filtering units are then used to form an eight-unit circular filtering array to generate vortex waves carrying OAM modes of l = ±1. Simulated results show that the proposed filtering array can generate vortex waves with high purity of more than 89%. Moreover, using two antenna arrays, the wireless communication is also simulated and the isolation between two OAM modes is larger than 14 dB, which further verifies the orthogonality between the generated two OAM modes. Our proposed antenna array with filtering characteristic can not only enhance the channel capacity but may also help to avoid abnormal frequency interference, which shows great potentiality in wireless communication.

Circular antenna array optimization using modified social group optimization algorithm

Antenna arrays have potential applications in Radar, mobile, broadcasting, astronomy and other defense and commercial platforms. The design of antenna arrays is essential as they are capable of controlling the radiation pattern in terms of sidelobe level (SLL), beamwidth (BW), nulls and beam steering. Among several geometries of antenna arrays, the circular antenna arrays have the advantage in terms of inherent capability to control the phase implicitly. In this paper, circular antenna array synthesis is presented using novel metaheuristic techniques like the Social Group Optimization Algorithm (SGOA) and Modified SGOA (MSGOA). The main objective of the synthesis process is to synthesize radiation patterns with suppressed SLL while the BW being equal to the uniform distribution. A comparative study is performed to analyze the performance of various synthesis techniques like amplitude only, inter-element spacing only, and amplitude spacing. The MGSOA and SGOA have proved to be performing well in accomplishing the objective. Further, the CAA synthesis problem is translated into single-variable and multivariable optimization problems following which the obvious advantage associated with the inclusion of additional variable as an additional degree of freedom is demonstrated. The simulation is carried out in Matlab®, and results are analyzed using the plotted radiation patterns.

Array Manifold Measurement and Verification for UCA Calibration in Multistatic PCL System based on FM Broadcasting

This study describes a method of measurement and verification of array manifold of uniform circular array antenna applicable to multistatic Passive Coherent Location(PCL) system using FM broadcasting. In an environment of outdoor test where FM broadcast signals are scattered, array manifold measurement methods using network analyzer and multi-channel digital receiver are introduced. Also, the descriptions and solutions for the test limits of each measurement method and the considerations affecting the measurement accuracy are presented. In addition, to verify the validity of the measured array manifold, the gain and phase difference were compared with the array manifold data obtained by EM simulation, and the effectiveness and accuracy of the measured array manifolds were compared and analyzed by estimating the direction of arrival of the FM broadcast signal received from the multistatic PCL system. Keywords: Multistatic PCL, Uniform Circular Array, Array Manifold, DOA Estimation Keywords: 멀티스태틱 PCL, 원형 배열 ì•ˆí Œë‚˜, ì–´ë ˆì´ 매니폴드, 도래각 ì¶”ì •