On The Compact Satellite Terminal Antenna And Broadband Wide Beam Circular Polarization Antenna

The research works of the thesis are made with the scientific projects. The mainresearch works are divided into two parts: a compact antenna prototype for hand-heldterminal applications is introduced in the first part, which achieves the technicalparameters. The antenna has been delivered to Party A for actual applications and itsapplication effect is good. Then the design of broadband wide beam circularpolarization antenna is introduced, laying a certain foundation for subsequentprocessing prototype because of its good performance.The main contexts of the thesis are as follows:Firstly, according to the project requirements of the compact antenna for hand-heldterminal applications, the development history and current state of the Beidou and GPSsatellite antennas are introduced.The design difficulty in reducing the physicaldimension of the terminal antennas and evaluating the isolation between the elements issubmitted. Meanwhile, the technology and method of antenna miniaturization and lowercoupling are proposed. On the basis of Ansoft HFSS simulation and analysis, thephysical prototype is manufactured and measured. The simulated results show that thedesigned antenna for hand-held terminal applications has good performance in therequired frequency bands with VSWR＜2. In addition, the antenna is circularlypolarized. The antenna shows omnidirectional patterns in the azimuth plane and the gainin elevation planes is more than-5dB from30°to90°. On this basis, the antennaprototype is fabricated and measured. The measured results show that the designedcompact antenna for hand-held terminal applications has good performance in therequired frequency bands and omnidirectional patterns in the azimuth plane. Therefore,it can be proved that this design method is effective for application in engineering.Secondly, according to the project requirements of broadband wide beam circularpolarization antenna, some difficulties in achieving broadband, wide beam, andcircularly polarized are pointed out. On the basis of comparative analysis on traditionaldual-polarized microstrip antenna with double-feed, the dissimilar circular polarizationcharacteristics are obtained by adding different feed network. By adding cone structure,a two layer aperture-coupled microstrip patch antenna fed through gradual H-shapedslots in T-shaped arrange is presented. An electromagnetic software package, AnsoftHFSS is used for required numerical analysis to examine the performance of the proposed antenna. The simulated results indicate that the impedance and radiationcharacteristic have good consistency in the operating frequency band. The VSWR of theantenna is less than2and the AR (axial ratio) is less than6dB. Furthermore, thebeamwidth is wider than the required indicator, which achieves the basic requirementsof the broadband wide beam circular polarization antenna. The good performancemakes the proposed antenna as a good candidate for broadband circularly polarizedantenna array, laying a certain foundation on subsequent prototype development.