Indian Journal of Science and Technology

Abstract

Objectives: To design new multi-band antennas based on patch resonator with comparative results to each other. Both antennas are compact in size and have high quality responses which can be applied in many handheld and personal communication devices. Methods/Analysis: New microstrip patch antennas based on modified first iteration of Minkowski fractal geometry and applying central small square cut in the main resonator have been presented in this paper with and without inserting corner square patches. Both antennas have designed using single layer and dual feeds to operate as multi frequency devices. The antennas have been modeled and optimized by using the Microwave Office (MWO) simulator based on the method of moments. The projected antennas have been designed using FR4 substrate with a relative dielectric constant of 4.4 and a substrate height of 1.6 mm. Compared with the microstrip patch antenna without inserting corner patches using same main patch resonator dimensions and substrate specifications, the designed antenna with corner patches exhibits more operational frequencies as well as as greater frequency ratios with respect to the first fundamental frequency. Findings: New microstrip antennas based on patch resonator with and without inserting corner patches have been proposed. The first antenna exhibits multi-frequency behavior, where resonances appear to take place at frequencies of 2.49, 3.03and 6.63 GHz, within 2 to 7 GHz frequency range. The second antenna exhibits a higher number of resonant frequencies that appear at 2.14, 2.55, 5.03, 5.81, 5.9 and 6.14 GHz respectively under same previous frequency range. The first three operational frequencies have decreased or shifted by inserting corner square patches due to increased electrical physical dimensions of the second antenna. Also, these corner patches act as EM perturbation elements to stimulate the second antenna with more resonant frequencies within 2-7 GHz frequency sweeping range. Theoretically, there is an important relation between antenna dimensions and guided wavelength. This relation specifies if antenna dimension is less than quarter guided wavelength (λg ), then the antenna is impractical because radiation resistance, bandwidth and gain are decreased and therefore the antenna size is enlarged. By the way, the dimensions of Antennas 1and 2 have been found to be (0.259 λg x 0.259 λg ) and (0.269 λg x 0.269 λg ) respectively according to their fundamental frequencies which are satisfactory. Both antennas have small sizes and high quality responses which can be applied in many handheld and personal communication devices. Novelty/Improvement: In this paper, new multi-band antennas based on patch resonator have been proposed. The proposed resonators have been initiated from the transformed version of the first iteration of Minkowski fractal geometry. These antennas have compact dimensions with good return loss and radiation pattern performances which are desired features to be adopted in many communication devices.

Keywords: Compact Antenna, Electronic Design Automation (EDA), Microstrip Patch Antenna, Multi-frequency Antenna, Radiation Patterns.