Research On Dual-band Shared-aperture Patch Antennas With Large Frequency Ratio

With the rapid development of wireless communication technology,the integration of wireless communication equipment has an increasing high level,in recent years.A communication system often needs to work in different frequency bands.As the front end of a communication system,antennas play a crucial part in the wireless communication systems.If multiple antennas are used to operate at different frequency bands independently,it will not only space consuming but also cause electromagnetic compatibility problems.A shared-aperture antenna can be utilized to realize multi-band operation by sharing the same aperture,so it improves the space utilization of the antenna.Moreover,the development of communication technology and equipment also brings about the problem of spectrum shortage.As a result,more and more attention has been paid to millimeter-wave band owing to its rich spectrum resources,fast communication speed,and other advantages.However,millimeter-wave also has the disadvantages of short wave length,poor diffraction ability and so on,which can’t completely replace the application of the microwave band.Therefore,it is of great significance to study the dual-band sharedaperture antenna with high frequency ratio which can work in microwave and millimeter-wave band simultaneously.The main contents and innovations of this paper are as follows:First of all,this paper expounds the background and current research of the dual-band sharedaperture patch antenna with large frequency ratio.The key technologies of the shared-aperture antennas and the antennas with large frequency ratio are summarized.Meanwhile,the basic theory of the microstrip patch antenna is explained,which provides the basis for the subsequent antenna design.Secondly,a dual-band shared-aperture patch antenna unit with central frequencies of 3.5 GHz and 26 GHz is designed,realizing a central frequency ratio of 7.4.The patch of the low frequency band antenna is not only used as the radiation element but also serves as the ground plane of the high frequency band antenna.To avoid the deterioration of the low frequency band,an innovative method using the short-circuit point of low frequency patch antenna where the electric field is the weakest as the feed position of high frequency band is proposed.Finally,the above high frequency band patch is expanded to a 4×4 array antenna,and a parallel feed network composed of multistage T-type power divider is also designed.The maximum gain of high frequency band antenna array achieves 17.2dB,and the low frequency band patch radiator is also used as the ground plane of the array.The aperture size of the whole antenna is equal to the size of the low frequency antenna.As a consequence,the proposed design has a compact size and a high isolation level of 45 dB.