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

未来的蜂窝无线电系统比建立小小区之前提供更多的服务，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，市中心的购物区或繁忙的道路可能需要使用小型蜂窝。关于小区大小、要使用的频率和接入概念的设计可能会有很大的差异。一些实施例提供由可操控天线实现的用户跟踪。在这种情况下，这些小小区的小区半径通常以几十米的形式给出。因此，在购物中心或体育场安装基站天线的地点如灯柱、桥梁、天花板是首选的。由于基站的高度较低，因此，即使在相对较小的小区中，天线也必须能够在较大的角度范围内操纵其辐射瓣。这也导致基站天线和用户终端之间的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大的动态范围，这可能导致低效率。扫描损耗、方向图损耗和栅瓣进一步影响了这一情况，在本项目方案中，提出了一种天线概念，其中每个天线单元具有多个可选的首选方向图，这些方向图可以通过解耦的天线端口进行并行控制。因此，当在每个扇区操纵天线波瓣时，可以选择合适的方向图。多端口天线单元的综合是基于特征模理论的。通过馈电网络，在同一天线单元上激励合适的几组正交模，在探索基本连接方式的基础上，构建了5G场景中假设的小小区波束形成阵列作为演示实例。通过测量研究了天线的特性，特别是关于扇形波束形成的特性。

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.