| Wireless local area network(WLAN) is the combination of computer network and wireless communication technology. Based on the IEEE802.11 standard, it can be used in local area network environment in the ISM band of 2.4 GHz and 5 GHz spectrum for wireless connection. Due to the spectrum need no authorization and the development of wireless communication technology, WLAN is finding wider and wider application range. Antenna act as the key components of WLAN system, must also adapt to the development of WLAN communication technology. For these reasons, design of the high performance antenna that can meet the demand of WLAN communication is necessary, and has important significance and application value.At present there are three commonly used WLAN standards, namely the IEEE802.11 a, IEEE802.11 b and IEEE802.11 g. Among them, the 802.11 b and 802.11 g standard is using the 2.4 GHz frequency band(2.4 to 2.484 GHz), 802.11 a standard is using the 5 GHz band(5.15 to 5.35 GHz, 5.725 to 5.825 GHz). This paper mainly aimed at the three criteria of WLAN, and using electromagnetic simulation software HFSS designed two novel dual-frequency microstrip antennas. The two antennas are using normal FR4 materials as a dielectric substrate, with the advantages of low cost, small size. The first antenna adopts microstrip feed line and the radiation patch adopts a folding T-shaped patch and two rectangular patch. The symmetric structure makes the antenna with good performance of radiation pattern. The working frequency of the antenna is from 2.4 GHz to 2.52 GHz and 4.5 GHz to 7.5GHz which covers the three working frequency bands of the WLAN, and within the working frequency band the antenna also has good gain performance. The second antenna is a microstrip patch antenna feed by coaxial. Through the ladder type slot in the two sides of the patch, and the folded gap inside of the patch makes the antenna working in the 2.4 GHz and 5.2 GHz WLAN frequencies bands, and at the same time reduced the size of the antenna. |
