Study And Design Of Multiband And Integrated Antennas

As one of the most popular ways of communication, satellite communication has a variety of advantages. And as its key component, the miniaturization, broadband(including multiband) and integration of antenna has been increasingly focused and challenged. In demands of practical situation such as the limit of space, multiple antennas needs to function properly while being arranged together. In that case, problems such as mutual coupling among the antennas must be considered. Then, it is necessary to design multifunctional integrated antennas with good performances. Based on the design requirements of a communication system, three kinds of antenna structures have been adopted to design three groups of integrated antenna, which can cover six different operating bands, and form the final overall multiband integrated antenna.Firstly, a dual-band UHF integrated antenna is designed with miniature feature, which consists of two nested quadrifilar helical antennas(QHA) with different radiuses. By using the technique of arm folding, the antenna achieves the purpose of miniaturization. After analyzing the integrated antenna with ideal feed, a novel miniature feed network with double layer is proposed, and the final simulated results are given. The VSWR of the integrated antenna is lower than 1.21, and the elevation gain above 25° are over-1.31 d B and-1.00 d B separately for the two antenna elements.Secondly, an integrated antenna working in L- and S-band is proposed. Two printed quadrifilar helical antennas(PQHA) working in different bands are presented, analyzed, and nested to working together. After designing the feeding network, which is composed of Wilkinson divider and broadband phase shifter, simulated results are obtained for the integrated antenna with its corresponding networks. The results show that the VSWR of the L- and S-band are lower than 1.23 and 1.37 respectively, and the elevation gain above 25° are separately over-4.04 d B and-2.85 d B.Thirdly, a printed crossed dipole and a simple asymmetric patch antenna are proposed for the final group of integrated antenna. By employing an electromagnetically coupled method, the former antenna achieves broadband characteristic, and by folding parts of the radiation patch, miniaturization and wide beamwidth features are obtained simultaneously. The latter is a single-feed antenna operating in Beidou S-band. The VSWR of the two antennas are separately lower than 1.34 and 1.71, and the elevation gain above 25° are over-3.14 d B and-0.74 d B, respectively.Finally, an overall integrated antenna is obtained by combining three groups of integrated antennas mentioned above. The designed multiband integrated antenna can cover multiple navigational and satellite communication systems, achieving circular polarization and certain values of elevation gain above 25°.