The Realization Method And Application Of Multi-band Patch Antenna

With the advancement continuous of science and technology,wireless communication systems have become more and more complex.This phenomenon imposes higher requirements on antennas which serve as the key components in wireless systems,and pushes antennas toward the direction of miniaturization and multi bands.Compared with single-band antennas,multi-band antennas can reduce the number of antennas required in the system,leading to the save of space and the reduce of cost.Therefore,researches on multi-band antennas not only have great academic value,but also are beneficial to engineering applications.Based on microstrip patch antennas,three multi-band antennas are proposed in this paper.The main contents of this paper are listed as follows:A dual-band microstrip patch antenna for 2.4 GHz wireless local area network(WLAN)and 5.8 GHz WLAN is proposed.Based on a stacked structure,the lower circular patch is fed by energy coupling and the upper circular patch is directly excited.Due to the size difference of two patches,the design can operate at two different bands.The proposed antenna has omnidirectional radiation patterns and linearly polarized properties within two operating bands.Together with the advantages of simple structure and low profile,this design is suitable for WLAN applications.In addition,the frequency ratio of the antenna can be adjusted by changing the relative size of the two patches.Therefore,the proposed design has great flexibility.Based on design 1,a dual-band microstrip patch antenna applied in vehicles is proposed.In the lower band,the antenna has unidirectional radiation patterns with circular polarization,which enables the information transmission between vehicles and satellites.In the upper band,the antenna has omnidirectional radiation patterns with linear polarization.As a result,the communication between vehicles and surrounding base stations are realized.The design has different radiation characteristics over two bands and is made of full metal.It owns the merits of simple structure,high gain and low cost.A dual-band dual-mode patch antenna is proposed to be applied in global satellite positioning systems,WLAN and automotive communications.This design has two feeding ports: In the lower band,the feeding network is used to feed the lower patch through two Lshaped probes,and unidirectional circular polarization is realized.In the upper band,using the other feeding port,the upper circular patch is excited by the coaxial line.Then,omnidirectional linear polarization is obtained in the upper band.The proposed design utilizes the “short-circuit” position of the patch antenna and cleverly combines the low-frequency unit and the high-frequency unit together,achieving the advantages of broad bandwidth and high isolation.