This paper proposes an improved adaptive approach involving Bacterial Foraging Algorithm (BFA) to optimize both the amplitude and phase of the weights of a linear array of antennas for maximum array factor at any desired direction and nulls in specific directions. The Bacteria Foraging Algorithm is made adaptive using principle of adaptive delta modulation. To show the improvement in making the algorithm adaptive, results for both adaptive and nonadaptive algorithms are given. It is found that Adaptive Bacteria Foraging Algorithm (ABFA) is capable of improving the speed of convergence as well as the precision in the desired result.

Abstract-Recently the social foraging behavior of E. coli bacteria has been used to solve optimization problems. This paper presents an approach involving Bacterial Foraging (BF) to find appropriate included angle (ψ) and there by two other slant angles (θ 1 , θ 2 ) for which the V-dipole provides higher directivity in comparison to straight dipole. Symmetrical V and Straight dipole is analyzed completely using Method of Moments (MoM). MoM codes in MATLAB environment have been developed both for straight dipole and Vdipole to obtain impedance, directivity, and radiation patterns in both E-plane and H-plane. Then MoM codes is coupled with well known Bacteria Foraging Algorithm (BFA) to get best included angle. Moreover, some modification of BFA is done for the faster convergence.

The design of antenna array with desirable multiple performance parameters such as directivity, input impedance, beam width, and side-lobe level using any optimization algorithm is a highly challenging task. Bacteria Foraging Algorithm (BFA), as reported by electrical engineers, is the most robust and efficient algorithm in comparison with other presently available algorithms for global optimization of multi-objective, multi-parameter design problems. The objective of this article is to apply this new optimization technique, BFA, in the design of YagiUda array for multi-objective design parameters. We optimize length and spacing for 6 and 15 elements array to achieve higher directivity, pertinent input impedance, minimum 3-dB beam width, and maximum front to back ratio both in the E and H planes of the array. At first, we develop a Method of Moments code in MATLAB environment for the Yagi-Uda array structure for obtaining the above design parameters and then coupled with the BFA for the evaluation of the optimized design parameters. Detail simulation results are included to confirm the design criteria.

This paper presents an optimum design technique of an asymmetric V-dipole antenna and it's a three-element Yagi-Uda array using Genetic Algorithm (GA). The optimization parameter for the V-dipole is the directivity and that for the Yagi-Uda array are the input impedance and directivity. The theoretical analysis has been done using a Moment-Method technique in a very simple step-by-step way, and subsequently the GA is applied for obtaining the optimized parameters. Comparative results are provided for 3-elements straight dipole Yagi and V-dipole Yagi array. Further, analysis for directivity with respect to included angle is given for the GA based optimization problem that gives an important aspect in the design of V-Yagi.

A compact ultrawideband planar antenna with modified circular patch and a defective ground plane for multiple applications is presented. The proposed structure consists of a modified circular patch and rectangular parasitic elements with defective ground plane etched on flame retardant (FR‐4) substrate with 50 Ω feed line. Return loss (S11 < −10 dB) and the simulated bandwidth of the structure was 2.5 to 12.2 GHz with the fractional bandwidth of 131%. The overall volume of the structure had a compact size of 15 × 19 × 1.6 mm3. The gain of the structure is 3.5 dB, and the antenna efficiency is 73.5%. The structure radiated (stable radiations) omnidirectional and bidirectional patterns. Measured and simulated results of Co‐ and Cross‐polarizations. are in relatively good agreement. All these properties shows that the proposed structure is applicable in WiMAX‐band 3.5, 5.5 GHz, WLAN‐band 5.2, 5.8 GHz, X‐band8‐12 GHz, data links to satellites along with various applications in the wireless communication field.