Investigation And Design Of Microstrip Antennas For Wireless Communication

With the fast development of wireless communication, the electronic technology is further advanced. As an important component in wireless communication system, it has great effects on the performance of communication system. Because microstrip patch an-tenna has the advantages of low profile, light weight and being able to integrated with microwave circuits, it is widely used in practical application. But the application of mi-crostrip antenna has been limited by its disadvantages, such as narrow bandwidth, low gain and low efficiency. Through the efforts of many researchers, the bandwidth of the microstrip antenna has been expanded from 7% to 60% or 70%. Based on the research and conclusion of various references, we have designed 3 microstrip antennas suitable for GSM900, DCS, PCS and UMTS application. Specific research works are as follows.1. Analyzes the methods used to reduce antenna size (1. use shorting plates and ground; 2. optimize the structure of antenna; 3. load the antenna with high dielectric ma-terial) and methods used to expand impedance bandwidth (1. increase the height of sub-strate; 2. add slot or slit on the patch or ground; 3. use three-dimensional structure).2. A dual frequency antenna operates at GSM900/1800. This antenna consists of two elements working at 900MHz and 1800MHz respectively, the feeding network is a simple T-junction. Each element of the antenna could be adjusted independently, and the design procedure is simplified. 3. Broadband antenna operates at DCS/PCS/UMTS. The feeding scheme is H-shaped aperture coupled feed. The width, length and height of the patch antenna is 40mm,23.5mm and 10mm respectively. It could well cover the frequency band from 1700MHz to 2200MHz, and is suitable for DCS, PCS and UMTS application.4. A broadband antenna operates from 0.7GHz to 10GHz. This antenna consists of a fork-like patch and an L-shaped ground. In order to increase the bandwidth, a vertical ground is added, a tapered structure is used at the feeding point and a rectangular notch is cut on the patch. It well covers the frequency range from 0.7GHz to lOGHz with VSWR<2.