A NOVEL ELECTRICALLY-SMALL MICROSTRIP GENETIC ANTENNA

One of the most challenging problems in antenna design is that of the electrically-small antenna. A novel genetic antenna with electrically-small property is presented. To make use of the simple and low cost microstrip fabrication techniques, this antenna adopts a two-dimensional microstrip structure rather than the commonly-used three-dimensional wire structure. It includes a 7-segment microstrip line as its radiator and is directly fed from a 50 Omega coaxial line without an impedance transformer that is necessary for most electrically-small antennas. After designed by a parallel Genetic Algorithm (GA) in conjunction with the Finite Different Time Domain (FDTD) method on a cluster system, a prototype antenna was fabricated and measured. Results show that its resonant frequency is only 0.775 GHz, which corresponds to a very small electrical size of 0.147 lambda and kr(e) = 0.46, where k is the wave vector in the free space, and r(epsilon) is the radius of the smallest sphere enclosing the entire antenna system.