Optimization of Reduced Size Microstrip Patch with slots using a Genetic Algorithm

Genetic algorithm optimization has been used in the past for size reduction of microstrip antennas by removing pixels from the entire metal area of the patch. This results in an unwieldy antenna that is not very practical. In the present work, a new methodology is developed for reducing the size of microstrip patch antennas by removing predefined slot shapes from the metal. A genetic algorithm is used to optimize the size and location of the slots on the patch in order to make it resonate at a much lower frequency. This technique is demonstrated for a 10 GHz patch antenna that is optimized to resonant at 6 GHz resulting in a 75% size reduction. The algorithm has been further improved to include a desired input impedance of 100 ohms into the fitness function in order to improve the overall gain. The work has been performed by interfacing the genetic algorithm to Ansoft High Frequency System Simulator (HFSS). Validation of the results is shown through design, construction, and measurement.