Design of small antennas for mobile devices

Abstract

The aim of this project is to design two identical dual-band antennas with space diversity in a small mobile device for GSM900/1800 system. The project consists of two parts. In the first part, an inverted-L planar monopole is designed. The antenna is mounted on the side of the copper case (110L x 70W x 10H mm3) of the devices. Similar to iphone4's antenna design, the antenna is folded into L-shaped around the sides of the case. A new double-layer patch design is introduced in the antenna. The required bandwidth for GSM900 and GSM1800 are also covered. In the second part, by using space diversity, two identical antennas are mounted on the same case to improve the quality and reliability. To reduce the mutual coupling and get higher isolation between the two internal dual-band antennas, different methods are tested and used. The stimulated and experimental results are compared and studied.