Ali Akdagli

Null Steering of Linear Antenna Arrays Using a Modified Tabu Search Algorithm

A useful and flexible method based on the tabu search algorithm for the pattern synthesis of linear antenna arrays with the prescribed nulls is presented. Nulling of the pattern is achieved by controlling the amplitude-only and both the amplitude and phase of each array element. To show the versatility of the present method, some design specifications such as the sidelobe level, the null depth and the dynamic range ratio are considered by introducing a set of weighting factors in the cost function constructed for the tabu search algorithm. Several illustrative examples of Chebyshev pattern with the imposed single, multiple and broad nulls are given.

A clonal selection algorithm for null synthesizing of linear antenna arrays by amplitude control

This paper presents a clonal selection algorithm based on human immune system for null steering of linear antenna arrays by controlling only the element amplitudes. Design requirements such as the null depth level, maximum sidelobe level, and dynamic range ratio are considered in the optimization process. Several examples of Chebyshev pattern with the imposed single, multiple and broad nulls are given to show the accuracy and flexibility of the proposed clonal selection algorithm.

Antenna array pattern nulling by controlling both amplitude and phase using modified touring ant colony optimization algorithm

This paper presents an efficient method, based on the modified touring ant colony optimization algorithm, for null steering of linear antenna arrays by controlling both the amplitude and the phase of array elements. The maximum sidelobe level, the null depth level and the dynamic range ratio are taken into account in the pattern synthesis. Simulation results for Chebyshev patterns with the imposed single, multiple and broad nulls are given to show the effectiveness of the proposed method.

Clonal Selection Algorithm for Design of Reconfigurable Antenna Array with Discrete Phase Shifters

In this paper, a method based on the clonal selection algorithm (CLONALG) is presented to design a reconfigurable dual-beam linear antenna array with excitation distributions differing only in phase. The CLONALG is a relatively novel population-based evolutionary algorithm inspired by the clonal selection principle of the human immune system (IS). From the practical implementation viewpoints, the proposed method takes discrete phase shifters into account during synthesis. Numerical examples showing a good agreement between the desired pattern and the synthesized pattern by using CLONALG are given.

Pattern Nulling of Linear Antenna Arrays By Controlling Only the Element Positions With the Use of Improved Touring Ant Colony Optimization Algorithm

An efficient search technique based on the improved touring ant colony optimization algorithm is presented for pattern nulling by controlling only the position of linear antenna array elements. The relative importance between the null depth level and the maximum sidelobe level is also considered by introducing a set of weighting factors in the cost function constructed for the improved touring ant colony optimisation algorithm. The frequency memory feature of tabu search is used in the improved touring ant colony optimization algorithm. To verify the validity of the technique, illustrative examples of Chebyshev pattern with the imposed single, multiple and broad nulls are given.

A new effective patch radius expression obtained by using a modified tabu search algorithm for the resonant frequency of electrically thick circular microstrip antennae

A new, very simple expression for the effective patch radius is presented for the resonant frequency of electrically thick circular microstrip patch antennae. It is obtained by using a modified tabu search algorithm, and is useful for the computer-aided design (CAD) of microstrip antennae. The theoretical resonant frequency results obtained by using this new effective patch radius expression are in very good agreement with the experimental results available in the literature.

Interference suppression of linear antenna arrays by phase-only control using a clonal selection algorithm

In this paper, an efficient technique based on clonal selection algorithm (CLONALG) for linear antenna array pattern synthesis with null steering by controlling only the element excitation phases is presented. The CLONALG is an evolutionary computation method inspired by the clonal selection principle of human immune system. To show the versatility and flexibility of the proposed CLONALG, some examples of Chebyshev array pattern with the imposed single, multiple and broad nulls are given. The sensitivity of the nulling patterns due to small variations of the element phases is also investigated.

Simple Formulas for Calculating Resonant Frequencies of C and H Shaped Compact Microstrip Antennas Obtained by Using Artificial Bee Colony Algorithm

Accurate and simple formulas are presented for effective length in determining the resonant frequency of C and H shaped compact microstrip antennas (CMAs) operating on UHF band. For this purpose, 144 C-shaped CMAs and 216 H-shaped CMAs having different physical dimensions and various relative dielectric constants were simulated by packaged software called XFDTD based on finite difference time domain (FDTD) method. The physical and electrical parameters of the antennas and their respective resonant frequency values were given as inputs to artificial bee colony (ABC) algorithm to determine unknown coefficients of the effective length expression which provides the best fit to the resonant frequency. The resonant frequency results of the effective length expressions were compared with the different measurement, simulation and calculation results published earlier in the literature. It was shown that our results are in very good agreement with the simulated and measured results as compared to those of calculated by the other suggestions reported elsewhere. Moreover, C and H shaped CMAs were fabricated in this work and then the accuracy and validity of proposed expressions were tested and verified. Major benefit of the formulation proposed here is that it provides accurate results without necessitating any other calculations.

A Novel Expression in Calculating Resonant Frequency of H–Shaped Compact Microstrip Antennas Obtained by using Artificial Bee Colony Algorithm

In this paper, a new, simple and accurate expression for the resonant length in calculating resonant frequency of H–shaped compact microstrip antennas at UHF frequencies applications is presented. H–shaped compact microstrip antennas with a range of different physical dimensions built on various substrates are numerically simulated with a software package based on finitedifference time domain method. A closed-form expression for the resonant length is constructed with the aid of both the artificial bee colony algorithm and the simulation data. The resonant frequency is then calculated by means of this resonant length expression. The average percentage error is found to be less than 0.79% for 216 simulated antennas. Experimental and simulated results reported elsewhere have been employed to illustrate the validity and accuracy of the present formulation.

A CLONAL SELECTION ALGORITHM FOR ARRAY PATTERN NULLING BY CONTROLLING THE POSITIONS OF SELECTED ELEMENTS

In this paper, a method based on clonal selection algorithm (CLONALG) is proposed for null steering of linear antenna arrays by controlling only the positions of selected elements. The CLONALG is a relatively novel population-based evolutionary algorithm inspired by the clonal selection principle of the human immune system. In order to illustrate the accuracy and flexibility of the proposed algorithm, several numerical examples of Chebyshev pattern with the single and double nulls imposed at the directions of interference are given.