| Antenna is an important part of wireless communication system.With the continuous development of communication systems,wireless mobile terminal devices are becoming more and more miniaturized,wideband,and multiple frequency bands.Therefore,the antennas used in these wireless mobile terminals also need to have the same characteristics.and traditional microstrip antennas are widely used by researchers due to their advantages of small size,light weight,low cost,simple manufacture,and easy integration.However,the microstrip antenna also has its own limitations.The high Q of the microstrip antenna leads to a narrower band of this type of antenna.To obtain sufficient bandwidth requirements,the size of the antenna must be increased.This goes against the trend of miniaturization of antenna.In order to overcome this contradiction,this article mainly draws on the related theory of microstrip antennas and constructes three structures of PIFA antennas that first two antennas are dual-band antennas and the third antenna is three-band antennas.Using simulation software for simulation optimization to view the performance indicators of the antenna.The bandwidth of the antenna covers the operating frequency band required by the design.At the same time,the overall size of the antenna is small and the gain is high.Finally,the physical test is performed and the performance of the antenna is verified.This article mainly completes the following items:1.A dual-frequency PIFA antenna that can be applied to GSM/DCS communication system is studied.Changing the slotted position of the antenna surface,the height of the antenna and the size of the ground plate is to achieve the purpose of the antenna of broadband.The bandwidth of the antenna in the two communication systems is 110 MHz and 143 MHz,respectively.For practical applications,the high-frequency bandwidth of the antenna is 263 MHz and the relative bandwidth is14.6%,which meets the actual application requirements.In addition,the main performance parameters of the antenna were also studied,and actual objects were made according to the model size.The measured S11 parameter graph and the simulation results are highly coincident,indicating that the antenna design is feasible and effective.2.A miniaturized dual-frequency PIFA antenna for a WLAN terminal was studied.By changing the relative position between the patch and the ground plate and the widthof the long radiation branch,the antenna achieves miniaturized.the size of the antenna to 20 mm×8mm,antenna section height is only 5 mm.The bandwidth of the antenna satisfies the working frequency bands of WLAN 2.4 GHz and WLAN 5.2 GHz.The bandwidths are 135 MHz and 695 MHz respectively.through the simulation of the radiation directivity diagram and the gain can be seen that the performance of the antenna,finally make physical and measured,the results of the S11 parameter with the simulation result is roughly same,fully meet the requirements of design.3.Researched a miniaturized three-band PIFA antenna that can be used for WLAN/Wi MAX.In order to make the antenna produce three frequency bands without significantly changing the antenna's volume,a parasitic patch was added.The height of the patch is 6 mm and the size is 17 mm x 2 mm.The antenna can work in the frequency range of WLAN2.4/5.2GHz and Wi MAX2.5/3.5GHz,and simulates other performance parameters of the antenna.The results show that the impedance of the designed antenna is well matched. |
PDF Full Text Request