scholarly journals Design of Non-Uniformly Spaced Circular Arrays of Parasitic Dipoles for Lower Side Lobe Level with Maximum Directivity

2018 ◽  
Vol 7 (1) ◽  
pp. 51-56 ◽  
Author(s):  
H. Patidar ◽  
G. K. Mahanti
Keyword(s):  
Mutual Coupling ◽  
Side Lobe ◽  
Side Lobe Level ◽  
Circular Array ◽  
Method Of Moment ◽  
Lower Side ◽  
New Approach ◽  
Circular Arrays ◽  
Maximum Directivity ◽  
Active Dipole

This paper presents a new approach for circular array of parasitic dipoles composed by one active dipole for reduction of side lobe level with maximum directivity including mutual coupling. The desired goal is obtained by changing the spacing between the parasitic elements and length of the parasitic elements while the position and length of driven element is fixed. In addition to it, reflection coefficient (RC) of the driven element is kept closer to the specified value. Matlab based method of moment code is used to evaluate the performance of circular antenna designs generated by QPSO algorithm. Two examples are presented to show the effectiveness of this proposed approach.  

scholarly journals Multiobjective Synthesis of Steerable UWB Circular Antenna Array considering Energy Patterns

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Leopoldo A. Garza ◽  
Marco A. Panduro ◽  
David H. Covarrubias ◽  
Alberto Reyna
Keyword(s):  
Antenna Arrays ◽  
Side Lobe ◽  
Main Beam ◽  
Side Lobe Level ◽  
Optimized Design ◽  
Circular Array ◽  
Circular Arrays ◽  
True Time ◽  
Uwb Applications ◽  
Circular Antenna Array

True-time delay antenna arrays have gained a prominent attention in ultrawideband (UWB) applications such as directional communications and radar. This paper presents the design of steerable UWB circular array by using a multiobjective time-domain synthesis of energy pattern for circular antenna arrays. By this way we avoid individual beamforming for each frequency in UWB spectrum if the problem was addressed from the frequency domain. In order to obtain an energy pattern with low side lobe level and a desired main beam, the synthesis presented is performed by optimizing the true-time delays and amplitude coefficients for the antenna elements in a circular geometry. The method of Differential Evolution for Multiobjective Optimization (DEMO) is used as the optimization algorithm in this work. This design of steerable UWB circular arrays considers the optimization of the true-time exciting delays and the amplitude coefficients across the antenna elements to operate with optimal performance in the whole azimuth plane (360°). A comparative analysis of the performance of the optimized design with the case of conventional progressive delay excitations is achieved. The provided results show a good performance for energy patterns and for their respective power patterns in the UWB spectrum.

Circular aerial arrays for radio astronomy

1961 ◽  
Vol 262 (1308) ◽  
pp. 84-99 ◽  
Keyword(s):  
Radio Astronomy ◽  
Side Lobe ◽  
Correction Function ◽  
Side Lobe Level ◽  
Circular Aperture ◽  
Circular Array ◽  
Polar Diagram ◽  
Beam Shape ◽  
Correction Process ◽  
Dimensional Distribution

A new type of aerial array suitable for high-resolution observations in radio astronomy is explored theoretically. The array consists of a large number of aerial elements equally Spaced round a circle and electrically connected in phase. The power polar diagram is calculated for the cases when the circle is effectively continuous, and when the separation between adjacent elements is appreciable. In both cases the side-lobe level is rather high for most radio astronomical purposes, for which a process of aerial correction is required. The function of the correction process is to readjust the relative weights of the different spatial Fourier components to provide a suitable beam shape. A general method of aerial correction is developed in which the two dimensional distribution of brightness directly recorded by scanning is cross-correlated with a circularly symmetrical correction function , a process which is desirably performed in the instrument itself. The correction process allows one to convert the polar diagram of a ring-shaped array into (for example) the diagram of a uniform circular aperture of the same radius. The principal theoretical characteristics of the circular array are briefly compared with those of the Mills cross. It is found that while the process of aerial correction or ‘tapering’ is technically more straightforward in the cross, the circular array has the following advantages: (1) the length of transmission line (and hence attenuation) between each element and receiver is halved; (2) the number of elements required to gain the same information is reduced, approximately in the ratio 4: π ; (3) the beam possesses circular or elliptical symmetry; and (4) the system offers the possibility of direct phase and amplitude calibration with the aid of a transmitter situated on a central tower.

scholarly journals Conformal Array Pattern Synthesis Using a Hybrid WARP/2LB-MOPSO Algorithm

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Roghieh Karimzadeh Baee ◽  
Keyvan Forooraghi ◽  
Somayyeh Chamaani
Keyword(s):  
Degrees Of Freedom ◽  
Mutual Coupling ◽  
Side Lobe ◽  
Penalty Functions ◽  
Main Beam ◽  
Side Lobe Level ◽  
Initial Population ◽  
Pattern Synthesis ◽  
Conformal Array ◽  
Multiobjective Particle Swarm Optimization

This paper addresses conformal array synthesis as a constrained multiobjective optimization problem. Simultaneous reduction of side lobe level (SLL) and cross-polarization (XPL) level is aimed with a constraint on main beam direction. A hybrid of weighted alternating reverse projection (WARP) and two local best multiobjective particle swarm optimization (2LB-MOPSO) is proposed to optimize the pattern. First, the WARP method finds a moderate and feasible solution. Second, 2LB-MOPSO begins with an initial population including the solution of WARP and penalty functions for constraint handling. Involving WARP result in the initial population of 2LB-MOPSO leads to higher convergence rate, avoiding local extermum traps and less sensitivity to penalty functions. Compared to WARP method which stagnates rapidly, the proposed hybrid method gives better SLL and XPL after adequate iterations. In addition, as 2LB-MOPSO offers a set of optimum solutions (Pareto front) instead of a single solution, this method provides more degrees of freedom in selection of proper practical arrays. Finally, to examine the mutual coupling consideration in array design, the same procedure was applied ignoring the mutual coupling between elements. The results show that the SLL and XPL strongly depend on mutual coupling.

scholarly journals Improving the Performances of Microstrip Antenna Array using Defected Ground Structure

2020 ◽  
Vol 9 (3) ◽  
pp. 1081-1086
Keyword(s):  
Antenna Array ◽  
Power Distribution ◽  
Mutual Coupling ◽  
Impedance Matching ◽  
Side Lobe ◽  
Power Divider ◽  
Side Lobe Level ◽  
Patch Antennas ◽  
Defected Ground Structure ◽  
Ground Structure

In this paper, a two elements antenna array with defective ground structure (DGS) has been designed to achieve significant gain, polarization purity and reduced mutual coupling. A 3 port Wilkinson power divider has been designed at 4.5 GHz frequency to obtain equal power distribution at the output ports. Two Rectangular microstrip patch antennas with DGS at the corners yield improved gain, impedance matching and polarization purity in both E and H plane. The reduction of mutual coupling and side lobe level (SLL) have been achieved by placing the dumbbell shaped DGS bellow the feed line of the power divider. The radiation performances obtained using the fabricated prototype agrees well with that of the simulated one. This array has been designed for C-band application.

scholarly journals Enhanced radiation characteristics for antipodal Vivaldi antenna using high permittivity dielectric director

2017 ◽  
Vol 07 (03) ◽  
pp. 1750018 ◽  
Author(s):  
Rabiaa Herzi ◽  
Moufida Bouslama ◽  
Ali Gharsallah
Keyword(s):  
Antenna Array ◽  
Frequency Band ◽  
Mutual Coupling ◽  
Side Lobe ◽  
Side Lobe Level ◽  
Radiation Patterns ◽  
Antenna Aperture ◽  
Radiation Characteristics ◽  
High Permittivity ◽  
Vivaldi Antenna

In this paper, we investigate the influence of higher permittivity dielectric director on the radiation performances of an antipodal Vivaldi antenna. An elliptical dielectric director with high permittivity is inserted in an antipodal Vivaldi antenna aperture in order to ameliorate the radiation characteristics of the antenna. Due to the capacity of elevated permittivity dielectric to confine and guide energy in the desired direction, an increment of 4[Formula: see text]dB in the gain of the antenna is obtained. This antenna, which covers an ultra-wide frequency band of 146.8% from 2.3[Formula: see text]GHz to 15[Formula: see text]GHz, has approximately regular radiation patterns with reduced side lobe level and narrower beamwidth. In the interest to achieve radar application necessities, the proposed antenna is exploited to develop an antenna array which consists of four connected elements. Adding dielectric directors can significantly enhance the radiations characteristics of the antenna and reduce the mutual coupling inter-elements. So using four elements with dielectric director in the antenna array can achieve the same results obtained with eight elements without directors. This can decrease the used number of elements that form the antenna array.

scholarly journals Thinning of Concentric Circular Antenna Arrays Using Improved Binary Invasive Weed Optimization Algorithm

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Huaning Wu ◽  
Chao Liu ◽  
Xu Xie
Keyword(s):  
Antenna Arrays ◽  
Optimization Algorithm ◽  
Optimization Technique ◽  
Side Lobe Level ◽  
Circular Array ◽  
Invasive Weed Optimization ◽  
Pattern Synthesis ◽  
Invasive Weed ◽  
Circular Arrays ◽  
Concentric Circular Arrays

This study presents a novel optimization algorithm based on invasive weed optimization (IWO) for reduction of the maximum side lobe level (SLL) with specific half power beam width (HPBW) of thinned large multiple concentric circular arrays of uniformly excited isotropic elements. IWO is a powerful optimization technique for many continuous problems. But, for discrete problems, it does not work well. In this paper, the authors propose an improved binary IWO (IBIWO) for pattern synthesis of thinned circular array. The thinning percentage of the array is kept equal to or more than 50% and the HPBW is attempted to be equal to or less than that of a fully populated, uniformly excited, and half wavelength spaced concentric circular array of the same number of elements and rings. Simulation results are compared with previous published results of DE, MPSO, and BBO to verify the effectiveness of the proposed method for concentric circular arrays.

scholarly journals Antenna array synthesis using a newly evolved optimization approach: Strawberry algorithm

2019 ◽  
Vol 70 (4) ◽  
pp. 317-322 ◽  
Author(s):  
Konidala R. Subhashini
Keyword(s):  
Antenna Array ◽  
Optimization Technique ◽  
Beam Width ◽  
Side Lobe ◽  
Side Lobe Level ◽  
Optimization Approach ◽  
Circular Array ◽  
First Time ◽  
Antenna Array Synthesis

Abstract An attempt has been made for the first time to apply this proposed Strawberry optimization technique to antenna array synthesis problem. The case study cited here refer to linear and circular array configurations. The design constraints are limited to minimizing the side lobe level and restricting the first null beam width, which play significant roles in antenna array performances. The key parameters which greatly influence in achieving the said objectives are either placement of antenna elements or amplitudes of excitations of these elements or both. And the recently reported meta heuristic nature inspired optimization algorithms have addressed to these problems quite effectively and the exciting result obtained using the said approach has undoubtedly proved the strawberry algorithm as a potential contender in the optimization domain.

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