D. Jamunaa, G. K. Mahanti, F. N. Hasoon,
Volume 16, Issue 2 (6-2020)
Abstract
This paper describes the synthesis of digitally excited pencil/flat top dual beams simultaneously in a linear antenna array constructed of isotropic elements. The objective is to generate a pencil/flat top beam pair using the excitations generated by the evolutionary algorithms. Both the beams share common variable discrete amplitude excitations and differ in variable discrete phase excitations. This synthesis is treated as a multi-objective optimization problem and is handled by Quantum Particle Swarm Optimization algorithm duly controlling the fitness functions. These functions include many of the radiation pattern parameters like side lobe level, half power beam width and beam width at the side lobe level in both the beams along with the ripple in the flat top band of flat top beam. In addition to it, the dynamic range ratio of the amplitudes excitations is set below a certain level to diminish the mutual coupling effects in the array. Two sets of experiments are conducted and the effectiveness of this algorithm is proved by comparing it with various versions of swarm optimization algorithms.
J. Fatemi-Nasab, S. Jarchi, A. Keshtkar,
Volume 17, Issue 1 (3-2021)
Abstract
In this study, a radiation pattern reconfigurable microstrip antenna is designed and fabricated. The antenna’s radiation pattern is directed in 9 different angles by employing a radiating patch and embedding complementary split ring resonators (CSRR) on the ground plane. The radiating patch is of circular shape, while for CSRR elements both circular and rectangular shapes are investigated. The antenna is excited through coaxial feed. There are four CSRR cells on the ground plane. With applying slots on CSRR’s arms and loading them by pin diodes, variable length CSRRs are obtained which result in radiation pattern reconfigurable property. Radiation characteristics of the antenna versus different switching modes of pin diodes are investigated and illustrated. The proposed antenna is also compact. The designed antenna was fabricated on FR4 substrate with thickness of 1.6 mm, and measurement results are provided. The results demonstrate that the presented antenna has impedance bandwidth of 2.39-2.47 GHz with a gain of more than 7 dBi.
