| Microstrip antenna is a kind antenna which is composed by add conductor slice on medium board. It has some advantages such as low profile, light weight, small volume, and low production cost. They also can be easily integrated with microwave integrated circuits and easily made into dual-frequency and dual-polarization antennas. From the initial microstrip antenna fabricated in 1970s, it has been developed widely, and be used in many area. All kinds of new microstrip antennas stuctures emerged in endless. They have been used widely in personal mobile communication, satellite communication, direct broadcast system (DBS), global positioning system (GPS) and vehicle carrying system and so on. And it is regarded as a specialty in the area of microwave antenna.But, in VHF/UHF(Very High Frequency/Ultra High Frequency),the standard microstrip antennas of half-wave length are still very big. And the standard microstrip antenna has a very narrow bandwidth of 1～5%. So in recent years, much attention has focused on the development of broadband antennas and compact antennas.Bluetooth technology was a standard of close quarters wireless communication which was constituted by Ericsson, IBM, Intel, Nokia, Toshiba. It is a exoteric global criterion of both wifeless data and audio communication. Its essential content is not only establishing universal Radio Air Interface for communication environment of both fixture equipment and mobile equipment, but also band together communication technology and computer technology. And what's more, with it, all kinds of 3C equipments can communicate and operate each other in close quarters without electrical wire or cable. WirelessLAN, for short WLAN, is a technology of accessing Ethernet quickly using the wireless technique. It is an outcome of the combination of the technology of the computer network and the wireless communication.Wireless LAN, for short WLAN, is a technology of accessing Ethernet quickly using the wireless technique. It is also an outcome of the combination of the technology of the computer network and the wireless communication, and a complement and extension for the wired network. The characteristics of WLAN are low-cost, fallibility, strong motion, high throughput and robust communication. Facing the new development of WLAN, the wireless networks for WLAN will have to be compatible with multimode and several criterions such as IEEE802.11a, IEEE802.11b and IEEE802.1Ig. Thus, a dual-band or two transmitters will be needed, which work at 2.4GHz and 5GHz separately.Based on the understanding of a great variety of microstrip antennas in the world, a novel design and research method for new microstrip antennas are proposed in this thesis, and the antenna's operation model and resonance principle are analyzed and demonstrated in depth. The main contribution of this thesis includes:First, the miniature and multi-band microstrip antenna techniques are studied, the feasibility of new miniature multi-band microstrip antennas with combination of several techniilues isproposed.Second, a novel design method for new microstrip antennas is proposed and researched. The study includes: (1) An innovative design and research method for miniature multi-band microstrip antennas with combination of U-slot and H-shape strip loading is proposed. It uses single layer to receive the effect of dual layer, and minish the size of the antenna, achieve the request of miniaturization.(2) Physical models and simulation of the novel miniaturemulti-band microstrip antenna are achieved; the antenna's operation principles are analyzed and investigated in depth. The achievements of physical models and principle analysis can be applied in design and research of new microstrip antennas in the future.Finally, a practical 2.2GHz/5.2GHz miniature multi-band microstrip antenna is designed, simulated and tested; the results of simulation and test verified the rationality and feasibility of work in the thesis.This paper use the HFSS v10 of Ansoft Company to simulate H-shape dual- frequency antenna with U-shape slot. The results indicate the antenna has good dual-frequency resonance characteristic, with its operating mode centered at about frequency 2.24GHz and 5.25GHz. The antenna has good gains which are more than 5dB at both resonant modes and its impedance bandwidths defined by VSWR=2 can meet the requirements of dual ISM bands. The paper analysis the effect of the parameters in detail.At the end of the thesis, some problems needed to be solved are discussed. |
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