Study Of Wideband Dual-Polarized Antennas Mounted On Compact Platforms

Antenna is the"sensory"component of wireless communication equipment,and its performance directly affects the performance of wireless communication system,so the high-performance antenna is very important for wireless communication system.The electrical performance of the antenna is not only related to its own structure,but also interwovenness related to the shape of the application platform and the installation position of the antenna on the application platform.Therefore,the antenna design for some specific application platforms is one of the"bottleneck"technologies that need to be solved urgently in engineering.In order to solve the technical problem that the common broadband dual-polarized antenna is too large to be applied to a small-sized platform,this dissertation studies the broadband dual-polarized antennas applied to compact platforms,and the research results have been applied in engineering and published on the journal of IEEE Transactions on Antennas and Propagation.The study is derived from scientific research projects.Firstly,the meaning of the wideband dual-polarized antenna is expounded,and the study status and existing problems at home and abroad are pointed out,and the study significance is explained,and the relevant theories used in this dissertation are given.Secondly,the main research work of this dissertation is given,and the research work is divided into three parts:the study of multi-band antenna on the compact platform,the study of wideband and dual-band dual-polarized antenna,and the study of wideband high-gain dual-polarized array antenna.The specific research contents are summarized as follows:1.Study of multi-band antenna on the compact platformAccording to the performance requirements of the antenna proposed by scientific research projects,a multi-band antenna including one L-band antenna,two SC-band antennas and two X-band antennas is needed to study,and these five antennas are fed independently and are installed on the same platform.According to the research requirements,the profile height and transverse dimension of L-band antenna should be less than 0.15?L,the polarization mode is linear polarization,the radiation pattern in azimuth plane has omnidirectional characteristic,and the radiation pattern in elevation plane has wide beam characteristic.In view of the above requirements,two types of antennas which are planar printed folded monopole antenna and umbrella printed monopole antenna are adopted to realize different radiation characteristics.The planar printed folded monopole is obtained by bending a simple planar monopole several times,which reduces the size of the monopole,improves the gain in zero depth direction and broadens the beam width.By using the two downward inclined arms of the umbrella-shaped printed monopole,the size of the umbrella-shaped printed monopole is reduced and a higher gain is obtained on the pitch plane.The SC-band antenna and X-band antennas should have dual-polarized,wideband and wide beam characteristics.Two orthogonal U-shaped microstrip lines are used to biased feed the cross-slot to realize dual-polarized characteristic,and a single-layer or double-layer metal patch carried by a dielectric substrate is loaded above the cross-slot to realize wideband characteristic.The slot-coupled stacked patch antenna is embedded into the cylindrical metal cavity,which reduces the transverse size of the antenna,improves the impedance bandwidth of the antenna and broadens the beam width.The antenna system is simulated and designed by HFSS electromagnetic simulation software.The design results show that the gain of planar printed folded monopole in zero depth direction is improved.The umbrella-shaped printed monopole has a"(?)"shaped radiation pattern.The SC-band antenna and X-band antenna obtain the characteristics of wideband,wide beam and miniaturization.The measured results of the prototype of the multi-band antenna are in good agreement with the simulation results.The measured results show that the performance of the multi-band antenna reaches the research goal,which shows the effectiveness of the design method.The research results have been applied in engineering.2.Study of wideband dual-polarized antennaThe same feeding mode as the above-mentioned SC-band antenna is adopted to realize dual polarization radiation characteristics.The long sides of the two orthogonal slots change exponentially,so as to improve the impedance bandwidth of the antenna.Multi-layer dielectric substrates and two layers of metal patches are loaded above the cross-slot to further improve the impedance bandwidth.The radiating layers and the feeding layers of the antenna are embedded in a small cylindrical metal cavity and the transverse dimension of the antenna is effectively reduced.The electromagnetic simulation software HFSS is used for simulation design,and the antenna prototype is manufactured.According to the measured results of the prototype,the impedance bandwidth of the dual-polarized antenna is 94%(2.47 GHz-6.85 GHz,|S11|?-10 d B).In the whole operating frequency band,the isolation between the two ports is greater than 21.2 d B.The radiation pattern is stable in the impedance bandwidth of 88.9%(2.5 GHz-6.5 GHz),and the measured results of the antenna are in good agreement with the simulation results.3.Study of dual-band dual-polarized antennaA dual-band dual-polarized patch antenna is designed based on the slot coupling feed structure in this part.Two orthogonal U-shaped feed-lines are used to excite the cross-slot to realize the dual-polarized characteristic.A circular patch and a narrow ring patch are loaded above the cross-slot,thus realizing the dual-band radiation characteristic.The stacked patch antenna is fixed in a compact metal cavity,and the transverse dimension of the antenna is reduced.The measured results of the prototype antenna show that the operating frequency of the antenna is 2.25 GHz-2.8 GHz and 5.02 GHz-6.0 GHz(VSWR<2.0),which can completely cover the two operating bands of WLAN.The transverse dimension of the antenna is 0.32l_L(l_L is the wavelength in free space corresponding to the frequency of 2.25 GHz).4.Study of wideband and high gain dual-polarized array antennaIn this part,the same feeding mode as the wideband dual-polarized antenna is adopted to realize the dual polarization characteristics of the antenna.Two dielectric substrates and two radiation patches are arranged above the cross-slot,and an air layer with a certain thickness is respectively arranged below the two dielectric substrates.A wideband and high-gain dual-polarized 4×4 array antenna is designed with the slot-coupled stacked patch antenna as the unit antenna.The array antenna is simulated and designed by HFSS electromagnetic simulation software,and the antenna prototype is manufactured.According to the measured results of the prototype of the array antenna,the impedance bandwidth reaches 64%(2.513 GHz-4.88 GHz).Within the impedance bandwidth,the average gain of the array antenna reaches 17.9 d Bi and the gain fluctuation is 2.2 d B.The designed wideband dual-polarized high-gain antenna is suitable for wideband mobile communication system.Finally,the main achievements of the dissertation and the problems to be further discussed are expounded in the conlusion.