Research On Wideband Multimode Antenna Design

With the continuous development of modern communication technologies,the requirements of the antenna performance is also getting higher and higher.There are many traditional methods of antenna analysis,but they either have limitations,or could not provide a clear physical insight into the radiation principles.In this paper,the design method of broadband antenna is discussed based on pattern analysis.Based on the discussed method,several broadband antennas are designed and analyzed.In this paper,the antenna port characteristics is studied by the characteristic mode theory,and the relationship between the series parallel-resonance and the mode resonance is analyzed.The results indicates that the parallel resonance occurs because of the multiple mode interaction.In comparison,the series resonance is the result of single mode resonance.These conclusions have been verified by dipole and probe-excited microstrip antennas.In antenna design section,three antennas including a four-port vehicle antenna,a microstrip dual-polarized antenna and a cross-dipole dual-polarized antenna are analyzed,designed and experimentally verified.Antenna structures and their resonant characteristics are analyzed from the resonant frequency,the characteristic current,the characteristic field and the port characteristic respectively.The radiation mechanisms and the design methods are described clearly,with a more satisfactory performance results received.In summary,the characteristic mode theory and antenna designs are combined together in this paper by studying the relationships between the resonant characteristics of the antenna port and the characteristic mode theory.One four-port antenna and two broadband dual-polarized antennas are designed and analyzed.The result shows that the design of the broadband antenna can be analyzed effectively by the theory of the multimode antennas.Different from traditional methods,the mode decomposition theory discussed here provides a widely applicable and effective analysis method for metallic antenna designs.