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The highly efficient linear and elliptical antenna array design presented in this article is intended to synthesize far-field radiation patterns for 5G communication. The objective is to achieve the best possible radiation pattern, which includes a lower side lobe level (SLL) and a narrower half-power beam width (HPBW). A low SLL is crucial to minimize intervention in the entire side lobe region, whereas long-distance communication requires a low HPBW. The marine predator's algorithm (MPA) is used here to determine the optimal feeding currents to each array element to reduce the SLL and HPBW values. Two linear antenna array (LAA) design examples and the three elliptical antenna array (EAA) design examples are discussed in this article which are achieved using the optimal current excitations to each array element. Two well-established evolutionary optimization techniques, namely the genetic algorithm (GA) and the differential evolution (DE) technique, are also employed for comparison to demonstrate the superiority of the MPA optimization-based technique. The results achieved utilizing the MPA show the improvement of SLL contraction compared to the uniform antenna array and the methods affirmed in the recently published article. [ABSTRACT FROM AUTHOR]

Introduction. When operating antennas in various radio-electronic systems, the influence of phase shifter (PS) failures on the characteristics of phased array antennas, waveguide-slot phased array antennas (WSPAA) in particular, should be taken into account. A review of publications shows a lack of research studies into failures of these elements.Aim. Research of WSPAA characteristics in the event of PS failures, when their phase takes a value equal to zero instead of the required value.Materials and methods. Statistical modeling methods were used to study the impact of PS failures on WSPAA characteristics. Calculations were carried out using a PC and the Mathcad 15 applied mathematics package.Results. An algorithm for statistical modeling of the impact of PS failures on WSPAA characteristics is proposed. A relationship that connects the radiation pattern with the statistical sample volume and the number of failed PSs is presented. Malfunctions of emitters from 5 to 35 out of 50 elements were investigated. Changes in the following characteristics were obtained: standard deviation - from 0.064 to 0.18; relative values: radiation pattern width - from 8 to 18 %; level of side lobes - from 13 to 59 %; radiation power - from 0.9 to 0.3.Conclusion. The results obtained can be generalized and used in radio-electronic systems with antenna arrays at the stage of their development. Future work will address the influence of PS failures with phases being established randomly and with random values, as well as PS failures in which power does not pass into the emitter. Another important area concerns compensation of distortions resulting from failures of antenna elements.

Summary: This study presents a novel method for reducing return loss and achieving lower side lobe levels in small planar antenna arrays (PAAs). Quantum particle swarm optimisation (QPSO) findings are utilised for antenna design modelling and performance assessment utilising the MATLAB‐based moment's code approach and MATLAB‐HFSS interface. The mutual coupling between antenna components is considered and computed using the method of moments (MoM). Changing the array elements' length and spacing will accomplish the abovementioned objectives. The Matlab‐based moments code calculates the antenna components' length and spacing, and the antennas' length and spacing are used to produce the radiation pattern via the Matlab‐HFSS interface. Four examples of small PAA designs are given to illustrate how well the applied methodology works. The method discussed in this paper is generic and can be employed in the future for different sizes of the array elements and the different antenna array structure designs. [ABSTRACT FROM AUTHOR]

This article introduces an innovative approach to antenna array design, focusing on synthesizing the optimal radiation pattern for fifth-generation (5G) communication. The authors have designed a reliable linear and elliptical antenna array (EEA) of dipole elements by employing sailfish optimization (SFO). 5G technology promises transformative improvements in wireless communication with high data rates, expanded capacity, minimal latency, and exceptional service quality. The crux of 5G lies in the precision of antenna array design, aiming for an emission pattern with minimal side lobe levels (SLLs) and a narrow half-power beam width (HPBW). A narrower HPBW is essential for efficient long-range communication, whereas reducing the SLLs enhances signal clarity. The SFO optimizes the current excitation of each antenna element for reducing the mutual coupling effects and lowering the SLL and HPBW values in linear and EEAs. This paper uses the exact excitation to each element to show the linear antenna arrays (LAA) (10-, 16-element) design examples and EAA (8-, 12-, 20-element) structures. The LAA and EAA design examples obtained with the SFO algorithm establish the advancement in SLL suppression over the uniform antenna array and the methods proclaimed in the recent article. [ABSTRACT FROM AUTHOR]

Introduction. Currently, the impact of phase shifter (PS) failures on the characteristics of phased antenna arrays, slotted waveguide array antenna (SWAA) in particular, represents a significant problem. A review of publications shows that insufficient attention has been paid to PS failures.Aim. To investigate the characteristics of a SWAA in the event of PS failures, when their phase takes a value equal to zero instead of the required value.Materials and methods. The methods of statistical modeling methods were used to study the impact of failures on SWA characteristics. Calculations were carried using the Mathcad 15 software package.Results. An algorithm for statistical modeling of the impact of PS failures on SWAA characteristics is proposed. A relationship that connects the radiation pattern with the volume of the statistical sample and the number of failed PSs is given. The malfunctions of emitters from 5 to 35 out of 50 elements were studied. Changes in the following characteristics were obtained: standard deviation – from 0.064 to 0.18, radiation pattern width – from 8 to 18 %, the level of side lobes – from 13 to 59 %, radiation power – from 0.9 to 0.3.Conclusion. The results obtained can be used in radio-electronic systems with antenna arrays at the stage of their development. Future work will address PS failures with phases being established randomly and with random values, as well as the case of PS failures where power does not pass into the emitter. Another important direction concerns compensation of distortions resulting from failures of antenna elements.

Pattern synthesis is widely used in many radar and communication systems and received great interest. So, this paper proposes a new beamforming strategy based on a hybrid combination between grey wolf optimizer (GWO) with ${\mathrm { L}}_{2}$ -norm called proposed GWO. This approach is applied to synthesized uniform linear arrays (ULA), Chebyshav arrays, and shaped pattern arrays. Moreover, it is utilized for side lobe level (SLL) and size reduction of antenna elements. In this strategy, the GWO is utilized to optimize the element spacing to adjust the half-power beamwidth (HPBW) to save it the same as desired pattern. Furthermore, the excitations of the antenna elements are optimized via the ${\mathrm { L}}_{2}$ -norm minimization problem. The proposed GWO has low complexity (fewer iterations and computing time) compared to other algorithms. In addition, it has a very accurate approximation of the original radiation pattern. As well, the computer simulation technology (CST) microwave package is utilized to achieve the practical validation of the proposed methodologies. As an application of the proposed GWO, it is employed to create a proposed hybrid beamforming (PHB) structure for Multi-input Multi-output (MIMO) systems. Consequently, the BS transmitting antennas are synthesized for gain maximization while utilizing the current amount of antenna elements. This results in considerable savings in antenna components and associated radio frequency (RF) chains which reduces system complexity. Furthermore, array gain maximization will increase the received signal-to-noise ratio (SNR). In addition, the SLL reduction scenario will decrease the interference from undesired users which in turn will also increase SNR. Hence, the performance of the system in terms of spectral efficiency (SE) and power utilization will be improved.

Currently, various applications of ultra-wideband signal–code constructions are among the most vibrant technologies, being implemented in very different fields. The purpose of this research consists of analyzing Barker codes and searching for the optimal nested representations of them. We also aim to synthesize signal–code constructions based on the tenets of nesting of alternative modified Barker codes, which employ an asymmetric alphabet. The scientific merit of the paper is as follows: on the basis of new analytic expressions, modified nested codes and signal–code constructions were obtained, applicable for the establishment of the unambiguous association of the component values of the nested codes with any lobes of the normalized autocorrelation function. With these analytical expressions, we are, hence, able to determine the values of the binary asymmetrical components of the nested codes related to the side lobes of the normalized autocorrelation function. In this way, we clearly obtain better (low) levels for these lobes than by using the autocorrelation function, as established by the equivalent conventional Barker codes, including the nested constructions. Practical application of these modulated ultra-wideband signals ensures improved correlational features, high-fidelity probabilistic detection, and more precise positional detection of physical bodies depending on the range coordinate. [ABSTRACT FROM AUTHOR]

Summary: This article presents a study on the placement of multiple nulls as well as minimization of side lobe level in the radiation pattern using a planar hexagonal antenna array structure in two different vertical planes. The desired null depth is achieved to suppress the interference signal by the position‐only control of the uniformly excited isotropic antennas in the array structure. The immediate solution to the mentioned computational problem is reached by various meta‐heuristic optimization algorithms such as teaching learning‐based optimization (TLBO), symbiotic organism search (SOS), and moth fly optimization (MFO) within a considerably reduced processing time with a control over the design constrains. Various examples for diversified scenarios are demonstrated to place multiple deep nulls in the radiation pattern without compromising the pattern constraints and all other radiation pattern characteristics. This experiment sought to illustrate and quantify the unique benefits and limitations of proposed technique using three considered meta‐heuristic optimization algorithm. [ABSTRACT FROM AUTHOR]

Summary: This research illustrates a precise linear and elliptical antenna array design for synthesising the optimal far‐field radiation pattern in the fifth‐generation (5G) communication spectrum using a meta‐heuristic optimisation technique known as black widow optimisation (BWO). 5G communication is an emerging technology with revolutionary changes in the wireless communication system with ultra‐high data rate, enhanced capacity, low latency and good quality of service. An accurate antenna array design for an ideal far‐field radiation pattern synthesis with a suppressed side lobe level (SLL) value and half power beam width (HPBW) is the most crucial aspect of 5G communications. A suppressed SLL is necessary to reduce interference in the entire side lobe region, whereas a low HPBW is required for long‐distance communication. Here, the BWO is employed to find the optimal feeding current to each array element to lower the SLL and the HPBW value. The BWO algorithm sustains impeccable equity between the exploration and exploitation stages to impact different potential regions of the search space and generate new solutions to attain the global optima by evading the trap of local optima. The design examples of the linear antenna array (LAA) and elliptical antenna array (EAA) are illustrated in this article by applying the optimal feeding currents to each array element. Compared to the uniform antenna array and methodologies described in the recently published literature, the results obtained utilising the BWO algorithm for designing the LAAs and EAAs demonstrate a substantial development in the reduction of SLL and HPBW. [ABSTRACT FROM AUTHOR]

The combination of antenna arrays with optimization algorithms aims to minimize SLL, Linear antenna arrays are an extensively used electromagnetic system in modern wireless communication. The improvement algorithms are the genetic algorithm GA, the flower pollination algorithm FPA, and the grey wolf optimization GWO. This has been implemented to reduce SLL and communicate the signal to the right place and the highest efficiency with the greatest amount of energy and by reaching the best solution. antenna arrays engineering was arranged in linearity and implemented in different numbers of elements, i.e.8,16,32,64,128, and 256 elements, Each algorithm has criteria that affect the reduction of SLL, In GA when considering the influential parameters represented by iteration, population size, and max stall iteration, the best effect is iteration where SLL is reduced to -32.9523dB and at 16-element at iteration 50. FPA has many influential parameters representing iteration, population size, probability, and flower attraction rate. The best of these effects is iteration. SLL reduced to -35.0696dB at iteration 300 and at 64-element. In GWO the influential parameters are iteration and population size the best effect, it was concluded, is iteration as well, which has reduced SLL to -32.8479dB at 8-element in iteration 140. [ABSTRACT FROM AUTHOR]

With the rapid development of communication technology, the problem of antenna array optimization plays a crucial role. Among many types of antennas, line antenna arrays (LAA) are the most commonly applied, but the side lobe level (SLL) reduction is still a challenging problem. In the radiation process of the linear antenna array, the high side lobe level will interfere with the intensity of the antenna target radiation direction. Many conventional methods are ineffective in obtaining the maximumside lobe level in synthesis, and this paper proposed a quantum equilibrium optimizer (QEO) algorithm for line antenna arrays. Firstly, the linear antenna array model consists of an array element arrangement. Array factor (AF) can be expressed as the combination of array excitation amplitude and position in array space. Then, inspired by the powerful computing power of quantum computing, an improved quantum equilibrium optimizer combining quantum coding and quantum rotation gate strategy is proposed. Finally, the proposed quantum equilibrium optimizer is used to optimize the excitation amplitude of the array elements in the linear antenna array model by numerical simulation to minimize the interference of the side lobe level to the main lobe radiation. Six differentmetaheuristic algorithms are used to optimize the excitation amplitude in three different arrays of line antenna arrays, the experimental results indicated that the quantum equilibrium optimizer is more advantageous in obtaining the maximum side lobe level reduction. Compared with other metaheuristic optimization algorithms, the quantum equilibrium optimizer has advantages in terms of convergence speed and accuracy. [ABSTRACT FROM AUTHOR]

In this paper, a novel approach for simultaneously correcting multiple degraded patterns under the failure condition of time-modulated linear arrays is proposed. The approach is based on the use of trapezoidal pulse with non-zero rise/fall time to control the switching status of the radio frequency switches that enables ON-OFF keying modulation of the array elements. After deriving a closed form expression of harmonic power loss and through the in-depth analysis, it is explored that the proposed trapezoidal pulse, because of having non-zero rise/fall time, provides less undesired harmonic power loss as compared to the conventionally used rectangular pulse with ideally zero rise/fall time. With the aim of reconstructing the degraded patterns with improved directivity and suppressed higher sideband power, three pulse-switching strategies based on rectangular and trapezoidal pulse have been employed, and their comparative performances prove the superiority of the proposed approach. [ABSTRACT FROM AUTHOR]

The fifth generation (5G) of telecommunications is an attractive application for many researchers during the last years. The 5G requires high date rate with low latency communication medium and patch antenna was used recently for this application. In this article a patch antenna for 5G at 38 GHz was proposed. This article worked on enhancing the gain of patch antenna at Ka-Band and reducing side lobes level (SLL) in radiation pattern. The gain of the patch antenna was improved using a reflector layer located under antenna's ground with free space air gap separating between two layers. Moreover, the SLL were reduced to satisfy low latency condition for 5G communications. The proposed antenna shows high gain around 8.10 dB with high front-to-back (F/B) ratio of 16.24 dB and wide operating bandwidth around 1.4 GHz for high data rate requirements as well as having reduced overall size antenna. The article based on analytical calculations for patch dimensions and optimization procedure to achieve the desired performance of antenna. Computer simulation technology (CST) had been used as an environment for simulation. [ABSTRACT FROM AUTHOR]

Here, a novel wide‐angle scanning array antenna composed of subarrays with variable radiation patterns is proposed. The subarray consists of two antenna units with tilted beams. With a specially designed feeding network, the phase difference between the antenna units of each subarray keeps the same as that between subarrays. Thus, the radiation pattern of the subarray automatically changes with the array factor. Theoretical analysis shows that the array scanning range can be expanded and the side lobe level (SLL) can be suppressed. A linear array is designed, fabricated, and measured to verify the presented method. The simulated and measured results agree well with each other. The results show that the array can scan from −70° $-70^\circ $ to 70° $70^\circ $ with gain fluctuation of less than 3 dB and SLL lower than −8 $-8$ dB. [ABSTRACT FROM AUTHOR]

A circularly polarized microstrip antenna array with low side lobe levels is proposed for Vehicular Satellite Communication. The suppression of side lobe levels is accomplished by the non-uniform power distribution utilized to feed the individual patch elements. Impedance matching is ensured by the incorporation of a quarter-wave transformer via a microstrip line fed to the edge of the patch. When the proposed amplitude-weighted feed is compared to the conventional corporate feed, simulation results indicate a reduction in side lobe levels of 8.9 dB. The proposed antenna is constructed out of RT/DUROID 5880 material, which is lighter, more flexible, and less expensive than ceramic materials. The radiation characteristics of the proposed antenna are compared when the antenna is planar versus when it is made to conform to the roof of the vehicle. The measured results indicate a reflection coefficient at the resonant frequency of -31.5 dB and -27.7 dB when conformal, an impedance bandwidth of 410 MHz and 180 MHz when conformal, an axial ratio bandwidth of 140 MHz and 170 MHz when conformal, and a peak gain of 15.719 dB and 14.335 dB when conformal. The measured results validate the simulation results that this proposed antenna is appropriate for a variety of Vehicular Satellite Communication applications. [ABSTRACT FROM AUTHOR]

A high gain antenna array with reduced side lobe level (SLL) needs to be optimized and designed to meet the requirement of modern wireless communication systems. To achieve this goal, a newly developed natural heuristic algorithm namely sparrow search algorithm (SSA) and its modification are introduced and utilized to the field of electromagnetic optimization for the first time in this paper. Simulation results over several different examples of the linear antenna array (LAA) and circular antenna array (CAA) design problem have been presented to demonstrate the effectiveness and superiority of the modified SSA. The design results obtained by modified SSA showed greater advantages than those certain classical and well-known algorithms like particle swarm optimization (PSO), whale optimization algorithm (WOA) and grasshopper optimization algorithm (GOA), in a statistically meaningful way. [ABSTRACT FROM AUTHOR]

This study proposes a double-layer metasurface which is capable of conducting independent amplitude and phase modulation for transmitting x -polarized waves under y -polarized incidence. The phase modulation is controlled by regulating the opening angle of the middle metal ring. Meanwhile, amplitude modulation is achieved by adjusting the rotation angle of the opening ring structure. The cross-polarized transmission response achieves complete phase and amplitude coverage and exhibits wideband characteristic with which a 3 dB gain bandwidth of 54.6% (5.4–9.5 GHz). The polarization isolation level is lower than −20 dB. In the wideband frequency range, the average sidelobe level of phase-only modulated metalens antenna is less than −20 dB with the lowest value of −22.5 dB, and the intermediate sidelobe level of amplitude-phase independent modulated metalens antenna is less than −25 dB with the lowest value of −27.4 dB. Both numerical simulated and experimental results verify that the proposed metalens antenna realizes a 4.8 dB averages of the sidelobe level suppression compared with the phase-only modulation metalens antenna. Holding strong anti-interference performance due to its superiority in polarization isolation level and side lobe level, the proposed antenna embraces broad application prospects in point-to-point communication systems in jamming environments. [ABSTRACT FROM AUTHOR]

5G antenna arrays are being designed to generate a dedicated stream of data for every single user. This results in more capacity and speed over the network along with the least possible latency rate. Depending upon the direction of the user demanding internet access, the beam can be steered in that direction. Meanwhile, the occurrence of side lobes in such systems can be menacing. The smart antenna is a pivotal technology for modern cellular communication. It helps the user's signal to determine the direction of arrival It also estimates antenna arrays using an adaptive signal processing algorithm that produces a radiation beam for communication. This work presents beamforming for uniform linear smart antenna array using leaky least mean square algorithm and side lobe level reduction using array synthesis methods like Tchebycheff and Taylor distribution. Multiple interferers are considered for the smart antenna. Here, one of the aims is to reduce side lobe levels nearer to the main beam which can enhance more efficient frequency reuse in a cellular network. Side lobe level is reduced up to about 16 dB that enacted for signal-to-noise ratio to 20 dB. [ABSTRACT FROM AUTHOR]

Abstract In this paper, two H‐plane horn antennae are designed using groove and ridge gap waveguide (GGW and RGW) techniques. In the proposed structures, the gap waveguide is partially filled with a dielectric to control the amplitude and phase distribution across the antenna aperture so that a very low side lobe level (SLL) can be achieved. Two sample antennae are designed and simulated for the frequency range from 12 to 16 GHz, and the prototypes are fabricated. The fabricated antennae show quite wide impedance bandwidth (S11 ≤ 10 dB) of 28% and 32% for the RGW and GGW versions, respectively. The obtained maximum side lobe level for the designed GGW and RGW horns is about −30 and −24 dB, respectively, over the operating bandwidth. In comparison with state‐of‐the‐art designs, the proposed structures introduce much lower SLL.

Currently, various applications of ultra-wideband signal–code constructions are among the most vibrant technologies, being implemented in very different fields. The purpose of this research consists of analyzing Barker codes and searching for the optimal nested representations of them. We also aim to synthesize signal–code constructions based on the tenets of nesting of alternative modified Barker codes, which employ an asymmetric alphabet. The scientific merit of the paper is as follows: on the basis of new analytic expressions, modified nested codes and signal–code constructions were obtained, applicable for the establishment of the unambiguous association of the component values of the nested codes with any lobes of the normalized autocorrelation function. With these analytical expressions, we are, hence, able to determine the values of the binary asymmetrical components of the nested codes related to the side lobes of the normalized autocorrelation function. In this way, we clearly obtain better (low) levels for these lobes than by using the autocorrelation function, as established by the equivalent conventional Barker codes, including the nested constructions. Practical application of these modulated ultra-wideband signals ensures improved correlational features, high-fidelity probabilistic detection, and more precise positional detection of physical bodies depending on the range coordinate.

This paper presents the application of CORPS (coherently radiating periodic structures) for feeding CRA (concentric rings array) with a reduced number of phase shifters. The proposed design technique for the structure of concentric rings provides a better scanning capability with respect to other existing configurations. This design technique utilizes 2 × 3 or 4 × 7 CORPS networks depending on the configuration or the number of antenna elements in the phased array system. These CORPS networks are set strategically in the feeding network to provide several advantages with respect to others in the scanning capability and the reduction of the number of phase shifters of the array system. The contribution of this paper is the full antenna system design of phased CRA for analyzing scanning and the reduction of phase shifters. The proposed phased array reduces the number of phase shifter devices in CRA for a scanning range of ±25° in the elevation plane. Differential evolution (DE) was applied to optimize the amplitudes of the proposed system. Several design cases were analyzed using full-wave simulation results to verify the phased array model and to take mutual coupling into account. Full-wave simulation results provide radiation patterns with low SLL in all scanning directions. The proposed phased array was validated by experimental measurements of the full antenna system prototype. [ABSTRACT FROM AUTHOR]

In this article, a novel technique based on the combined utilization of slots in patch and ground plane is proposed to reduce the side lobe level (SLL) in the E-plane of a square patch antenna operating at TM03 mode. The concept of beam reshaping through surface current reorientation is explained in detail by an analytical model and the same is validated through simulated as well as measured results. The combination of a complementary split-ring resonator (CSRR)–shaped slot, two plus-shaped slots on the patch and a plus-shaped defected ground structure (DGS), reduces the SLL by 14.7 dB and increases the half-power beamwidth (HPBW) and first null beamwidth (FNBW) by 21° and 42°, respectively, in comparison to the conventional square patch antenna. Starting from the basic expression of the E-plane radiation pattern of a square patch, an analytical model is invoked to modify this basic expression as per the structural modification to get the final expression for the proposed antenna structure. The physical insight for the stepwise modifications of the antenna structure is properly explained and justified. Analytical and simulated predictions are experimentally verified using a prototype. The simulated and measured results show a good agreement. [ABSTRACT FROM AUTHOR]

This paper presents an efficient method to improve the far-field radiation pattern of concentric circular antenna array (CCAA) design using two stochastic optimization algorithms known as social spider algorithm (SSA) and modified social spider algorithm (MSSA). Low side lobe level (SLL) plays a crucial role in reducing the interference with the other frequency components along the entire side lobes of the far-field radiation pattern. SSA and MSAA are the state-of-the-art evolutionary optimization techniques which are applied here to determine the optimal current amplitude and the inter-element distance between two consecutive antennae of the 3-ring CCAA. In this paper, the optimal results achieved by using SSA, MSSA for (4, 6, 8) elements and (8, 10, 12) elements 3-ring CCAAs, with and without centre elements are reported. The results achieved by employing SSA and MSSA show a considerable improvement in SLL reduction as compared to the uniform and the other array patterns reported in the state-of-the-art literature. [ABSTRACT FROM AUTHOR]

In this paper, a novel approach for synthesizing multiple radiation patterns with reduced hardware complexity in the feed network by exploiting the additional degree of freedom ‘time’ in time modulated unequally spaced linear array (TMUSLA) is presented. In the proposed approach, with a suitable common set of element position of TMUSLA, the desired dual-beam pattern with low sidelobe level (SLL) is obtained by simply controlling the ON-OFF time sequence of the RF switches connected to the array elements. To show the effectiveness of the proposed array synthesis method, two dual beam patterns - first one as pencil (sum) beam (PB) and flat-topped beam (FTB) pattern, and the second one as sum and difference pattern with different constraints have been synthesized. For the successful generation of the desired power patterns, differential evolution (DE) algorithm is employed to obtain the optimum possible solution in terms of common element position, time-modulation, switching sequences and applicable excitation phase for the desired shape beam patterns. The superiority of the proposed approach with the favourable improved performance have been demonstrated by comparing the realized patterns with the state-of-the-art relevant reported works.

The work carried out the calculation and synthesis of antenna arrays used in radio-electronic complexes on unmanned aerial vehicles. The analytical model is designed to find asymptotic estimates of the polarization components of the electric field of the grating in the far zone of the carrier surface; the results obtained with its use are the initial data for constructing a technique for the numerical solution of a boundary value problem for a grating on a carrier surface in the CST MWS electrodynamic simulation environment. The synthesis of gratings with the maximum achievable coefficient of directional action is carried out with the control of radiation patterns at a given set of angles. A two-mirror antenna system has been calculated. It is shown that with an increase in the number of re-reflections taken into account, the convergence of the result for the calculated characteristics of the antenna is observed. To test the proposed method, the same antenna was calculated using the integral equation method. The comparison showed a high degree of agreement between the results obtained by two different methods. The results of the simulation based on a software algorithm designed to quantify the input matching at the input of a multichannel frequency-scanning antenna array power divider are presented. It was found that when performing wide-angle scanning in a relative frequency band of more than a few percent, the disadvantage of the known method for eliminating the normal effect is a sharp deterioration in matching in the lower and upper frequencies of the operating range. A new method is proposed based on an automated iterative process of optimizing the divider geometry, which makes it possible to obtain an acceptable match over the entire operating frequency band. The feasibility of switching from a serial power divider construction scheme to a series-parallel scheme is analyzed for wide-angle scanning in a relative frequency band of about 5%.

In the present paper three evolutionary algorithms are compared and discussed for synthesizing a linear array of dipole antenna of half-wavelength oriented horizontally. All the dipoles are mutually coupled and designed to radiate the flat-top beam (FTB) pattern including multiple single null steering with little ripple deviation. The adopted evolutionary algorithms are; flower pollination algorithm (FPA), firefly algorithm (FA) and back tracking search algorithm (BSA), respectively. These algorithms are then combined with an efficient Inverse Fast Fourier Transform (IFFT) for reduction in the computation of evaluating time meaningfully. The required synthesis is attained by generating the current amplitudes at 00 and 1800 using binary phase shifters for the antenna array. The performance analysis of key antenna parameters along with the statistical parameters is achieved with the help of the optimization process and compared. In this paper, the MATLAB tool is used as a validation tool and the obtained simulation results are very satisfying and acceptable.

A novel method of designing unequally spaced time-modulated arrays (UESTMAs) by handling fewer optimization parameters with reduced problem dimension is presented in this paper. For synthesizing UESTMA, two design parameters, specifically, the non-linear parameter - element position, and the linear parameter – on-time durations are optimized in two steps. Different possible cases of linear and non-linear synthesis methods such as, position-only (PO), on-time only (OTO), position then on-time (PTOT), on-time then position (OTTP), and simultaneous position on-time (SPOT) are considered. To examine the performance of the synthesis methods, three global search stochastic algorithms based on differential evolution (DE), teaching-learning-based optimization (TLBO) and quantum particle swarm optimization (QPSO) have been employed to achieve the array pattern with significantly suppressed side lobe levels and sideband levels. Through comparative study, it is observed that the two step non-liner to linear synthesis method by fewer optimization parameters is efficient to provide better pattern with less computation time.

A technique to perform the synthesis of sum patterns which can achieve beam shaping using individual heights of side lobes is presented. The side lobes can be adjusted to any arbitrary specification, and flat-top far-field radiation patterns are generated using enhanced flower pollination algorithm (EFPA) which is discussed in this paper. The problem of designing an array can be expressed as an optimization problem that aims to reduce the first two side lobes to − 50 dB and by reducing the remaining side lobes to − 40 dB in case 1. The EFPA is applied to determine the excitation coefficients of their amplitudes so as to obtain the required pattern. The objective for case 2 is to obtain the flat-top sector beam for specified angular regions. Complex excitation coefficients are determined using EFPA for various beam widths. The radiation patterns are generated numerically using the obtained excitation coefficients. The results reveal that not only the ripples are controlled in the trade-in region, but the side lobe levels are also maintained in the acceptable limits. The results presented are very much useful for marine radar applications. [ABSTRACT FROM AUTHOR]

Optimizing the current distribution of an evenly spaced antenna array has shown to be an efficient approach for reducing side lobe levels. In this article, the Tchebyscheff distribution-based antenna array synthesis approach is combined with an adaptive signal processing algorithm for beamforming and side lobe level reduction in smart antennas in various fading situations. The performance of smart antennas in uniformly spaced linear, planar, circular, and semi-circular arrays are evaluated. The presence of Rayleigh and Rician channels is examined in the network. The least mean square (LMS) and normalised least mean square (NLMS) algorithms are applied as adaptive algorithms. In fading environments, the NLMS algorithm with Tchebyscheff distribution outperforms than the LMS algorithm with Tchebyscheff distribution, with a side lobe level decrease of 11.23 dB. The lowest side lobe achieved with the NLMS algorithm with Tchebyscheff distribution is − 45.59 dB for uniform planar array. [ABSTRACT FROM AUTHOR]

In this paper, two H‐plane horn antennae are designed using groove and ridge gap waveguide (GGW and RGW) techniques. In the proposed structures, the gap waveguide is partially filled with a dielectric to control the amplitude and phase distribution across the antenna aperture so that a very low side lobe level (SLL) can be achieved. Two sample antennae are designed and simulated for the frequency range from 12 to 16 GHz, and the prototypes are fabricated. The fabricated antennae show quite wide impedance bandwidth (S11 ≤ 10 dB) of 28% and 32% for the RGW and GGW versions, respectively. The obtained maximum side lobe level for the designed GGW and RGW horns is about −30 and −24 dB, respectively, over the operating bandwidth. In comparison with state‐of‐the‐art designs, the proposed structures introduce much lower SLL. [ABSTRACT FROM AUTHOR]

Summary: A novel synthesis method to reduce the maximum side lobe in the entire azimuth plane and for achieving a desired value of directivity of a concentric elliptical array antenna is addressed in this paper. Three well‐performing meta‐heuristic optimization algorithms, teaching learning‐based optimization (TLBO), symbiotic organism search (SOS), and quantum particle swarm optimization (QPSO), are employed to optimize the cost function and to obtain the desired radiation pattern. Different simulation‐based experiments are performed to obtain the best possible set of angular positions and the distribution of isotropic antennas across the ellipses by rigorously maintaining non‐overlapping constraints. The major benefit of the proposed design is the deprecation of interference in all phi planes. The statistical analysis of the simulation results demonstrate perceptible improvement compared with that of a uniformly spaced concentric elliptical array and hence show the efficiency of the proposed algorithms. In both simulation studies, the results obtained using TLBO, SOS, and QPSO are compared. Analysis of the results exhibits that for the stated objective, the TLBO‐ and SOS‐based side lobe reduction approach performs superior to QPSO method. Proposed multi‐objective research work could lead to reduce payload and can simultaneously achieve isoflux coverage in entire azimuth plane on the earth surface which can essentially be utilized in (Low Earth Orbit) LEO and (Geostationary Earth Orbit) GEO satellites applications. [ABSTRACT FROM AUTHOR]

A new technique for the restoration of the field pattern in a linear array constructed using parallel dipole antennas is carried out by altering the spacing between the array elements. In an N-element optimized linear antenna array, the differential evolution (DE) algorithm is used to correct a specific number of failed elements with the objective of achieving the specified side lobe level (SLL) and maximum reflection coefficient (RC). The mutual coupling effects of the pattern are taken into consideration here. The necessary simulations are performed using Matlab software which depicts the effectiveness of this technique in establishing the corrected far field radiation pattern approaching the desired radiation pattern. To prove its effectiveness, two examples are tested in this process. The simulation findings are verified using the FEKO electromagnetic simulation software. [ABSTRACT FROM AUTHOR]

In this paper, the effect of perfect electric conductor (PEC) as a ground plane on antenna array is investigated. Vertical electric dipole which is of infinitesimal small length is considered as an array element. The effect of mutual coupling is neglected in this work. The effect of PEC as a ground plane is analyzed by considering two cases in this paper. Firstly, the array elements are kept at constant height above PEC and in second case, the array elements are kept with gradually increasing height above the ground plane. Performance of antenna array in presence of PEC for both cases is investigated in terms of main lobe beam width and side lobe level using array factor pattern. Side lobe level and beam width results are compared both in presence of PEC and without PEC i.e. array in free space. It has been observed that there is improvement in the main lobe beam width and reduction in side lobe level when the array is used with PEC as a ground plane with elements kept at gradually increasing height from the ground plane. In addition to this, overall directivity of the array is also found to be increasing exponentially with height on application of ground plane in comparison with that of antenna arrays without ground plane. [ABSTRACT FROM AUTHOR]

In this paper, a novel approach for synthesizing multiple radiation patterns with reduced hardware complexity in the feed network by exploiting the additional degree of freedom 'time' in time modulated unequally spaced linear array (TMUSLA) is presented. In the proposed approach, with a suitable common set of element position of TMUSLA, the desired dual-beam pattern with low sidelobe level (SLL) is obtained by simply controlling the ON-OFF time sequence of the RF switches connected to the array elements. To show the effectiveness of the proposed array synthesis method, two dual beam patterns - first one as pencil (sum) beam (PB) and flat-topped beam (FTB) pattern, and the second one as sum and difference pattern with different constraints have been synthesized. For the successful generation of the desired power patterns, differential evolution (DE) algorithm is employed to obtain the optimum possible solution in terms of common element position, time-modulation, switching sequences and applicable excitation phase for the desired shape beam patterns. The superiority of the proposed approach with the favourable improved performance has been demonstrated by comparing the realized patterns with the state-of-the-art relevant reported works. [ABSTRACT FROM AUTHOR]

This paper presents the application of CORPS (coherently radiating periodic structures) for feeding CRA (concentric rings array) with a reduced number of phase shifters. The proposed design technique for the structure of concentric rings provides a better scanning capability with respect to other existing configurations. This design technique utilizes 2 × 3 or 4 × 7 CORPS networks depending on the configuration or the number of antenna elements in the phased array system. These CORPS networks are set strategically in the feeding network to provide several advantages with respect to others in the scanning capability and the reduction of the number of phase shifters of the array system. The contribution of this paper is the full antenna system design of phased CRA for analyzing scanning and the reduction of phase shifters. The proposed phased array reduces the number of phase shifter devices in CRA for a scanning range of ±25° in the elevation plane. Differential evolution (DE) was applied to optimize the amplitudes of the proposed system. Several design cases were analyzed using full-wave simulation results to verify the phased array model and to take mutual coupling into account. Full-wave simulation results provide radiation patterns with low SLL in all scanning directions. The proposed phased array was validated by experimental measurements of the full antenna system prototype.