Research on the development of dielectric-loaded super-high-efficiency small planar antennas by injection compression molding approach

采用注射压缩成型方法制备了介电球。然后将这些介质材料加载到原型微波平面天线表面，以提高天线增益。这次测试的原型天线是一个x波段波导天线。要实现高增益天线，必须认识到阻抗匹配的重要作用。在本研究中，我们首先尝试了波导与单槽的匹配，然后尝试了单槽与介电球的匹配。然后将该结构扩展为多槽波导阵列。考虑了两种类型的波导天线。一种是蛇形波导馈电天线，在方形平面天线中，馈电波导在天线壁上左右弯曲。这种天线的特点是天线可以被构造成一层低轮廓的天线，在波导中传播的同时辐射无线电波。然而，在这种天线中，匹配过程变得复杂。另一种天线是平行波导馈电天线。在这种类型的天线中，可以独立完成馈电分支和辐射结构的匹配程序，从而实现相对容易的匹配程序。在f=12 GHz的“紧凑范围”下，对原型蛇形波导馈电天线进行了辐射方向图测量。研究发现，在辐射槽表面加载介电材料可以提高天线的前增益，但会增加一些远角旁瓣电平。通过确定合适的介电材料参数来最大化孔径效率还有待进一步的研究。

By using injection compression molding approach, dielectric spheres were fabricated. These dielectric materials were then loaded on the surface of a prototype microwave planar antenna for the purpose of enhancing the antenna gain. The prototype antenna tested this time is an X-band waveguide antenna.To realize a high-gain antenna, we must recognize that an impedance matching plays an important role. In this study, we first tried a matching of a waveguide with single slot, and next a single slot with a dielectric sphere.Then this structure was extended to a multi-slot waveguide arrays.Two types of waveguide antennas were considered. One is a snake-waveguide-fed antenna, where a feed waveguide is bent right and left at the antenna walls in a square planar antenna. The feature of this type of antenna is that the antenna can be constructed as one-layer low-profile antenna, radiating radio waves while propagating in the waveguide. In this antenna, however, the matching procedure becomes complex.The other type of antenna is a parallel-waveguide-fed antenna.In this type of antenna, the matching procedure can be done independently for the feed branch and for the radiating structures, enabling relatively easy matching procedures.Radiation pattern measurements of the prototype snake-waveguide-fed antenna were conducted at f=12 GHz in the "compact range." It has been found that the front gain of the antenna is improved by loading dielectric materials on the radiating slot surfaces, though some far-angle side-lobe levels were increased.Further studies are left for maximizing the aperture efficiency by determining the proper parameters of the dielectric materials.