Ka波段垂直馈电托盘阵列空间功率合成放大技术研究

【作者】 张同超；

【导师】 张荣君； 汪海勇；

【作者基本信息】 复旦大学 ， 电子与通信工程， 2010， 硕士

【摘要】 本文的目的是根据工程需要设计一个Ka波段功率输出大于2W的功率放大器。不同于传统的电路级功率合成,本放大器采用的是可以集成更多放大单元的垂直馈电托盘阵列空间功率合成形式。该种结构在国外已取得很大发展,但国内少有相关工作的报道。在这种结构中,垂直馈电托盘阵列可以由多路放大及辐射单元组成,并把自由空间作为功率分配及合成的媒介,在放大单元的一侧通过微带贴片天线进行接收,在放大单元的另一侧通过微带贴片天线进行发射。本文首先研究了介质加载波导喇叭的原理及设计技术,介质加载波导喇叭是功率分配及合成网络的重要组成部分,它相对于传统的波导喇叭具有更均匀的电场分布,从而可以增加功率的分配及合成效率。然后,本文研究了功率分配及合成网络的另一重要组成部分——矩形微带贴片天线的设计理论及方法,该矩形微带贴片天线为常规形式,但是其馈电结构采用的则是一种新型方法,即在微带基片接地面的中心开缝,然后该细缝连接一段垂直于微带贴片天线的介质填充波导,利用电磁耦合将微带贴片天线的功率转换到介质填充波导中,介质填充波导的另一端通过阶梯阻抗匹配转换到微带电路上。在这种结构中,输入端的微带贴片天线与输出端的微带贴片天线之间只有微带电路一种通道进行连接,其余部分均为可屏蔽电磁波的接地面,因而该两微带贴片天线间没有电磁干扰,具有良好的信号隔离。在理论上对功率分配及合成网络进行了分析和设计后,本文利用三维电磁仿真软件对各个部件进行仿真,从而得出回波损耗、近场方向图、电场分布以及各支路的耦合度。另外,本文还针对GaAs pHEMT MMIC功放芯片的散热进行了可靠性设计。为了保证样品与设计结果的一致性,本文还列举了放大阵列的装配工艺的关键点及注意事项。经过调试,放大器样品在工作频段内的饱和输出功率大于设计要求的2W,且有一定的富裕量,输入端口的回波损耗及放大器的增益也可以满足使用要求。更多还原

【Abstract】 The primary objective of this thesis is to design a Ka-band power amplifier with minimum 2W output power, in order to satisfy the engineer needs. Different from the traditional circuit-based power combing methods, this work applies spatial power combining of perpendicularly-fed tray array for its potential to combine more unit cells. Such structure has been applied abroad, but there is little relevant report in China.In this structure, the perpendicularly-fed tray array can consist of large numbers of amplifying unit cells and radiating element. This combining method uses free space as the low-loss power dividing/combining medium, receiving on one side and transmitting on the other by microstrip patch antenna.Firstly, this thesis presents the theory and technology of hard-horn as an important part of dividing/combining sections. Contrast to the common rectangular waveguide horn, hard horn has more uniform field distribution, so the dividing/combining efficiency can be increased. Then, this thesis presents the design theory and method of rectangular microstrip patch antenna which is another part of the dividing/combining sections. Even though this microstrip patch antenna is ordinary, a new approach is developed for the feeding of this antenna. In the feeding network, a slot at the center of the substrate is etched connecting to a dielectric filled waveguide which is perpendicular to the microstrip patch antenna. And this perpendicular feeding mechanism employs several enhancements over the previous array, such as increased antenna isolation between the input and the output port, because there is no other signal channel between the input antenna and the output antenna beside the microstrip circuit. On the base of the researches above, each section is simulated using 3D electromagnetic simulation software to acquire the Return Loss, near-field radiation pattern, electromagnetic field distribution, and coupling coefficient of each channel. In addition, the method of heat sinking is investigated in order to enhance the dependability of GaAs pHEMT MMIC PA.In order to match the design result and the test result of the sample, the key issue of assembly of PA tray array is described, while the experimental results of power dividing/combining network and the total amplifier module are particularized. As a result, the maximum output power of this amplifier can exceed 2W, while the return loss and gain can achieve the demand in the operating frequency band.更多还原