Research on design and measurement of aperture antennas for millimeter-wave wireless LAN

为了实现高性能的毫米波无线局域网，人们研究了喇叭和反射镜的赋形波束设计方法和多波束天线技术。首先，在喇叭天线中，为了产生高阶模式并获得指定波束形状的孔径分布，引入了一种新的曲线锥形和多阶梯形来构造喇叭锥形。作为设计实例，分别研制了覆盖圆形区域的高增益圆孔喇叭和椭圆区的矩形孔径喇叭。通过对其制作的变幅杆的数值和实验评估，验证了所提出的设计方法。此外，为了在高增益覆盖特定区域的同时抑制旁瓣电平，利用二次规划法确定了此类喇叭的最佳模式系数。由于多模喇叭可以用作反射面天线的主喇叭，因此反射面天线的制造和测量都是在毫米波范围内进行的。其次，在反射阵列天线中，针对多波束天线和宽带天线，研究了微带阵元阵列与频率特性的关系。对所设计的反射镜的性能进行了数值分析和实验研究。此外，还研究了毫米波近场天线的测量，以简单地评估此类天线的性能。最后，提出了一种用于喇叭馈电系统的新型波导滤光片结构和频率选择表面的优化设计方法，以获得多频段反射阵列。

For achieving millimeter-wave wireless LAN with high performance, new shaped-beam design procedures and multi-beam antenna techniques for horns and reflectarrays have been studied. First, in the horn antennas, in order to generate higher-order modes and obtain the aperture distribution for specified beam shape, a novel curved-taper profile and a multiple-step configuration are introduced to construct the horn taper. As design examples, a circular-aperture horn covering a circular area with high gain and a rectangular-aperture horn for elliptical area have been developed, respectively. The proposed design procedures are verified by numerical and experimental evaluation of their fabricated horns. Furthermore, to suppress sidelobe level while covering a specified area with high gain, optimum mode coefficients of such horns are determined by using quadratic programming approach. Since multimode horns can be used as a primary horn of reflector antennas, fabrication of reflector antennas and their measurements are performed in the millimeter-wave region. Second, in the reflectarray antennas, relationship between array of microstrip elements and frequency characteristics is investigated for multi-beam antenna application and broad band use. The performance of the designed reflectarray has been discussed numerically and experimentally. Besides, millimeter-wave near-field antenna measurement is studied to simply evaluate the performance of such antennas. Finally, a novel structure of waveguide filters used as a feed system of the horns and optimization design procedure for frequency selective surfaces to obtain a multi-band reflectarray has been developed.