Antenna concept for sectorized beamforming using predefined antenna patterns in small cells

未来的蜂窝无线电系统提供比以前更多的小型蜂窝，为许多用户提供高数据速率的服务。除了体育场馆、机场和铁路终点站之外，市中心的购物区或繁忙的道路也可能需要使用小型基站。有关蜂窝尺寸、使用频率和接入概念的设计可能会有很大差异。一些实施例提供通过可操纵天线实现的用户跟踪。在这种情况下，这些小单元的单元半径通常为几十米。因此，基站天线的安装地点如灯柱、桥梁、购物中心或体育场馆的天花板等是首选。由于基站的高度较低，因此，即使是相对较小的小区，也有一个很大的角度范围，在这个范围内天线必须能够控制其辐射瓣。这也会导致基站天线和用户终端之间LOS（视线）连接的路径长度非常不同。因此，基站的TR模块的放大器必须已经覆盖了很大的动态范围，这可能导致低效率。扫描损耗、模式损耗和光栅瓣进一步影响了这种情况。在本项目提案中，提出了一种天线概念，其中每个天线元件具有多个可选择的优选图案，可通过解耦的天线端口并行控制。因此，当每个扇区控制天线瓣时，可以选择合适的方向图。因此，去耦扇区TR模块只需具有较低的功率动态范围。多端口天线单元的合成是基于特征模态理论的。利用馈电网络，在同一天线单元上激励合适的正交模组。在探索了基本连接之后，构建了5G场景中假设小蜂窝的波束形成阵列作为演示示例。天线特性，特别是关于扇形波束形成，通过测量进行了研究。

Future cellular radio systems provide more than before the establishment of small cells to supply many users with high data-rate services. In addition to sports stadiums, airport and rail terminals, shopping areas in inner cities or busy roads may require the use of small cells. Designs regarding cell size, frequencies to be used and access concepts can vary widely. Some embodiments provide user tracking enabled by steerable antennas. The cell radii of these small cells in such a scenario are often given as a few tens of meters. Installation sites for base station antennas as lampposts, bridges, ceilings in shopping centers or stadiums are therefore preferred. Due to the low height of the base station, therefore, even with a relatively small cell, there is a large angular range within which the antenna must be able to steer its radiation lobe. This also results in very different path lengths of the LOS (Line of Sight) connection between the base station antenna and the user's terminal. The amplifier of a TR module of the base station must therefore already cover a large dynamic range, which can lead to low efficiency. Scan Loss, Pattern Loss and Grating Lobes further affect the situation.In the present project proposal, an antenna concept is proposed, in which each antenna element has a plurality of selectable preferred patters, which can be controlled in parallel via decoupled antenna ports. Thus, when steering the antenna lobe per sector a suitable pattern can be selected. The decoupled sectorial TR modules thus only have to have a lower power dynamic range.The synthesis of the multi-port antenna elements is based on the theory of characteristic modes. By means of feed networks, suitable sets of orthogonal modes are excited on the same antenna element.After exploring the basic connections, a beamforming array for a hypothetic small cell in a 5G scenario is constructed as a demonstration example. The antenna properties, in particular with regard to the sectoral beamforming, are investigated by measurements.