Trial Manufacture of Diversity Antennas Utilizing Multibeam Arrays

移动电话和个人便携电话等无线通信系统将被引入到数据通信网络中。为了实现这一目标，必须建立避免多径传播引起的衰落的技术。本研究提出了多波束阵列天线作为分集接收天线的应用，并通过试制和传播实验对其性能进行了评价。在1.5 GHz频段制作了矩形和圆形微带贴片天线的4元和8元阵列，并对其辐射方向图进行了评估。采用Butler矩阵网络作为BFN。8个元素的数组二维排列在平面上，阵列为正六边形加1个元素的形状。这是世界上第一个成功制造的平面多波束阵列。测得的辐射模式与理论相符，且各光束间的正交性良好。传播实验在面积为6.9 * 8.7[m]的房间内进行，准备了4种环境，即(a)发射天线处的空间是自由的或(b)有遮挡的，(c)将对电磁波有良好反射作用的窗户处的百叶窗拉下或(d)向上。在10%的累积分布下，8个支路的多样性增益为7.03 dB。数值模拟估计在1%的累积分布下，4个支路的累积分布为15.78 dB， 8个支路的累积分布为19.81 dB。随后，引入了一种精度更高的新型测量设备，采用改进的Blass网络作为BFN，在2.5 GHz频段对具有孔径耦合和圆极化的3元圆形贴片天线平面阵列进行了测试。在这种情况下，1%累积分布下的分集增益估计约为13 dB，与数值模拟结果吻合较好。

Wireless communication systems such as mobile telephones and personal handy phones are going to be introduced in date communication networks. For this realization, techniques avoiding fading due to multipath propagation have to be established. This research proposes the application of multibeam array antennas as antennas of diversity reception, and evaluates their performance by conducting trial manufacture and propagation experiment. 4-and 8 elements arrays of rectangular or circular microstrip patch antennas are fabricated at the frequency band of 1.5 GHz, and the radiation pattems are evaluated. Butler matrix networks are utilized as the BFN.The array of 8 elements are arranged on a plane two-dimensionally, with the array being a regular hexagon plus 1 element shape. This is the first successfully manufactured planar multibeam array in the world. The measured radiation pattems coincide with the theory, and the orthogonality between every beams are good. The propagation experiment have been conducted inside a room with 6.9 * 8.7[m] area, where 4 kinds of environment are prepared, i.e. (a) the space looking the transmitting antenna is free or (b) obstructed, and (c) the shutter at the windows which is good reflectors of electromagnetic waves are pulled down or (d) up. The observed diversity gain at 10% cumulative distribution was 7.03 dB by 8 branches. The numerical simulation estimates one at 1% cumulative distribution to be 15.78 dB by 4 branches, and 19.81 dB by 8 branches. Later, a new measuring equipment with higher accuracy was introduced, and a planar array of 3 elements circular patch antennas with aperture coupling and circular polarization was tested at 2.5 GHz band, where a modified Blass network was utilized as the BFN.The diversity gain in this case for 1% cumulative distribution was estimated to be about 13 dB,which was in good agreement with the numerical simulation.