A Novel Adaptive Antenna And Its Application To Mobile Communications

In the past decades, the digital signal processing technology has been progressing rapidly and its development has been seen clearly on the performance to cost ratio of digital signal processor (DSP) hardware. Benefited from this trend of DSP development, the adaptive antennas, which once have been applied to radar, sonar and relevant military communications successfully, have been found attractive to telecommunication engineers for dramatic system performance improvements when applied in cellular mobile communication systems. In fact, with application of adaptive antenna in base station, the different users' uplink signal can be separated and downlink signal' can be beam-shaped based on suitable adaptive signal processing of the array output data according to the specialized performance optimum criterion. Generally speaking, a significant improvement of carrier to interference ratio of the system can be achieved in this way. As a result, the capacity and channel transmission quality can be improved.Whereas, due to the complexity of the real radio propagation environment and various radio transmission techniques under different mobile communication standards, adaptive antenna in mobile systems, also named as smart antenna (SA), will have much distinct characteristics in realization compared to its traditional applicable styles. New problems will be emerging, and new tradeoff solutions should be considered. So the related topics, including radio propagation modeling, high performance antenna array design, effective algorithm studying as well as networks management strategy, should be considered as a whole, before we can obtain the optimum match between them ultimately. In other words, a new approach should be introduced to the application, in which not only the adaptive antenna but also the characteristics of cellular radio system are taken into consideration.In the main body of the dissertation, a new multi-beam adaptive antenna is put forward and analyzed as an alternative configuration of smart antenna, which is the one based on the Fresnel Zone Focusing structure. For better description of the physical mechanics and the performances of the new multi-beam adaptive antenna, two parts are arranged.First, the mechanism of the Fresnel phase-correcting focusing configuration, which is the main component of the new adaptive antenna, is discussed in depth and the systematic design technique of the configuration is concluded. In fact, the Fresnel zones in a plant firstly are treated as the result of intersecting between a plane and the ellipsoid family having the same transmitter and receiver locations as its focus. So the design of Fresnel zones not only can be extended suitable both to the central feeding construction and the off-axis ones, but also suitable to any conformal surface other than conplane design further. Then, with comparisons between the performance of one-dimensional (1-D) Fresnel Zone Phase-correcting (FZP) plate and the two-dimensional (2-D) ones, it is found that the analysis on 1-D FZP plate will give a thorough understanding to this kind of configurations. Based on similarities, it is more convenient to using the 1-D model both in theoretic and experimental research. In this way, researches on the FZP performances can be simplified as working on the radiation and focus fields of 1-D FZP with classical approaches well developed in electromagnetic radiating and scattering theory. Experimental researches are also carried out to verify the theoretical results. Several concerned parameters are frequency properties, cross-polarization etc., which are thought to be useful for the later application.In the second part, based on the good paraxial-scanning characteristics of FZP configuration, a novel multiple-beam adaptive antenna conformation is proposed by our research group, which configured with a feeding array in the focusing plane of the FZP structure. Adaptive processing is based on the output signal of the feeding-array. It is clearly, with the focusing pre-processing accomplished by...