| With the rapidly development of the communications technology, the spectrum resources are growing scarcity. In order to adapt to the needs of different users, communication equipments become more and more miniaturized and multi-function. Antenna plays very important role in communication equipments which faces the same demand. For this reason, many scientific research institutions around the world have developed the corresponding technique, such as frequencies and radiation patterns multiplexing technology. This paper discusses the multi-frequency, multi-polarized antenna, dual circular-polarized antenna, monopulse antenna, wide beam circular polarized antenna and patterns reconfigurable which combined with the practical applications. Finally, according to the actual problems of antenna, far-field measurement which under the finite distance. The method of far field measurement correction will be discussed in this paper. The author’s major contributions can be summarized as:1. The multi-frequency and multi-polarization antenna was studied. First, we design of a miniaturization antenna which used for the wireless communication terminal equipment. This antenna is operating with the WLAN, Wi MAX and UWB applications. It consists of a microstrip feed line and radiant ground. On the ground has a ring shaped and two inverted L shaped slot. According to turn the size of the slots, three operating bands can be produced respectively. The dimensions of proposed antenna are 40×40×1.5 mm3. Measurements show that the antenna effectively cover three wireless communication systems, the wireless local-area network(WLAN) 2.4 GHz with circular polarization(CP), the worldwide interoperability for microwave access(Wi MAX) 3.8 GHz and 6.2-8.3 GHz(28% at the operating frequency of 7.1GHz) for UWB application with linear polarization(LP). In the second part, we design a carrier wireless communication conformal antenna. The basic form of antenna is rectangular microstrip patch antenna which working in the indifferent resonant frequencies. By selecting different feed point, the two patches have a different polarization.2. The dual-circularly polarized monopulse antenna was studied. At the first, we design of a dual circularly polarized element for radiation array. The feed network is realized by the 3d B coupler. The radiation element adopts multilayered slot coupled microstrip structure which isolated the antenna radiation patch and feed network. It also provide enough space for the array antenna feed network and reduce the influence on the performance of microstrip feed network. Secondly we design a 2 x 2 dual-circular polarization array.By rotating the radiation elements, the cross polarization will be suppressed. Thirdly, according to the characteristics of monopulse antenna, a 4 × 4 array was designed. In order to suppress the cross polarization, the feed network was rotated too. Finally, according to the initial phase of the whole array, we design a monopulse comparators for left-hand and right-hand circularly polarized by using the 3d B hybrid couplers.3. The wide beam circular polarization antenna was studied. In order to achieve circular polarization antenna with wide beam and wide angle axial ratio, we use the structure of multilayer microstrip substrate and two feed for the radiation patch which between the two feed points have 90 degrees phase difference. In order to improve the axial ratio, the radiation patch is added an open stub. In addition, the antenna top medium plate has coupled patch which broadening the bandwidth of the antenna.4. The pattern reconfigurable antenna is studied. First, we study the rectangular microstrip antenna which fed by a coaxial. When the feed point is not at the same place, radiation patch will produce a different radiation pattern. Secondly, according to the characteristics of rectangular microstrip antenna, we design a rectangular patch antenna with dual feed points. When changing the amplitude and phase between the two feed points, the radiation patch will form the different radiation patterns. Finally, we design two feed network according to the amplitude and phase which corresponding to different patterns. The feeding net work includes a 3d B coupler with 90 degree phase shift which composed of dual beams and feed network base on Butler matrix which forms four beams.5. The correction of the far field measurement which under finit distance are studied. First, we discusse the characteristics of passive zone scalar wave function and vector wave function. Secondly discussed in cylindrical coordinates, the field vector wave function expansion, the expansion coefficients to obtain the field. The correction algorithm is mainly based on field function analysis of actual measurement of the obtained expansion coefficients, using the mode filter theory, the expansion coefficients of higher order terms in the filter. Finally according to seek infinite far zone field function expansion coefficient, to filter the test environment clutter and multipath diffraction on the test effect. To verify the validity of the method, respectively, carried on the numerical simulation and verification in practice.
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