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建立小型小区之前更多的服务，以向许多用户提供高数据速率服务。除了体育场馆、机场和铁路终点站之外，市中心的购物区或忙碌道路可能需要使用小型小区。关于小区大小、要使用的频率和接入概念的设计可以广泛地变化。一些实施例提供由可操纵天线实现的用户跟踪。在这样的场景中，这些小小区的小区半径通常被给出为几十米。因此，基站天线的安装地点优选为购物中心或体育场中的灯柱、桥梁、天花板。由于基站的低高度，因此，即使对于相对小的小区，也存在天线必须能够在其中操纵其辐射波瓣的大的角度范围。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、方向图损耗和光栅波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方向图，这些优选方向图可以通过解耦的天线端口并行控制。因此，当操纵每个扇区的天线波瓣时，可以选择合适的图案。因此，解耦的扇形TR模块仅需要具有较低的功率动态范围。多端口天线元件的合成基于特征模式理论。通过馈电网络，在同一个天线单元上激发合适的正交模式集合。在探索基本连接之后，构建了用于5G场景中假设小小区的波束成形阵列作为演示示例。的天线特性，特别是关于扇区波束形成，调查的测量。

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.