Design Of Dual-band Antenna And Dual-band Filter For GSM And WLAN Application

In recent years, with the rapid development of communication technology, people pay more attention to the requirement for the network communication, single frequency communication system is very difficult to meet the growing wireless communication requirements.Multiband communication system can greatly increase the communication capacity, and can save fabricating costs of the communication system, therefore, multiple frequency communication system has become the research focus in the academia field and engineering field. At present, Global System for Mobile Communications (GSM) and Wireless Local Area Network (WLAN) are two communication systems which are the most widely used. GSM0.9GHz and GSM1.8GHz are the dominant standard of global digital network,0.9GHz/1.8GHz dual-band GSM communication system has a broad application space, has great market demand, therefore, the study on the GSM dual-band communication system has great practical significance. After years of development, WLAN has formed a variety of WLAN network standards. Amang them,2.4GHz frequency band of the IEEE802.11standard and5.2GHz frequency band of the IEEE802.11standard are the most common used two frequencies, it is very important to study the2.4GHz/5.2GHz dual-band WLAN system.Antenna and the filter are the important devices in GSM and WLAN communication system, the task of this paper is to design the dual-band antenna and dual-band filter for the GSM communication system and WLAN communication system. In this paper, two new dual-band antennas were designed, one is applied for the0.9/1.8GHz GSM communication system, another is applied to2.4/5.2GHz WLAN communication system. The improved symmetrical dipole antenna structure was used for designing GSM dual-band antenna. The antenna is composed of two groups of symmetrical dipole a set of folding belt dipole was used to radiate the low frequency signal another group of butterfly dipole was used to radiate the high frequency signal for radiation. Compared with the traditional printed dipole antenna, the antenna designed in this paper increased a set of butterfly dipole. By adding a set of butterfly dipoles, not only reached the double-frequency effect, but also increased the bandwidth of the antenna. WLAN dual-band antenna was designed by planar monopole antenna, by digging a U-shaped slot to increase bandwidth. In this paper, the two filters were designed by the parasitic passband method of coupling dual-band resonators. Use one-half wavelength step impedance resonator to design the dual-band filter. Dual-band filters work in GSM0.9/1.8GHz frequency band and WLAN2.4/5.2GHz frequency band. In this paper, the design method of combining the theoretical analysis with optimizing by electromagnetic simulation software was adopted. According to the design results, the antennas and filters were fabricated and measured. The final measurement results show that all the design targets of the dual-band antennas and dual-band filters meet the design requirements.