A study on propagation characteristics of optically controlled millimeter waves guided along the H-guide and its application to leaky wave antenna

利用基于精确导波理论的数值计算方法，研究了泄漏毫米波在含光致等离子体层的半导体H波导中的传播特性。通过色散曲线的数值例子，揭示了导模向漏波高速转变的机理。首先用Muller方法求出复本征值方程的解，然后求出复传播常数和各个方向的波数。利用计算得到的功率流矢量，图形化地揭示了漏波的特性。从漏波的矢量图中可以看出，平均功率密度的方向随等离子体密度的变化而变化，而等离子体密度的变化是由照射强度引起的，同时也与工作频率有关。在这项研究中，我们获得了设计的基础数据，使用硅H-波导的漏波天线在26.5和40 GHz之间的范围。我们还计算了GaAs作为半导体插入到H-波导中的传播特性，预计其响应速度快，并且在更高的频率范围（如60 GHz）具有实际应用前景。作为实验研究，我们测量了H型波导喇叭辐射的漏波，并研究了由于照明强度引起的方向性特性，目前的测量结果与理论结果仍有一定的差异，对实验条件的改进是：

The propagation properties of leaky millimeter waves in the semiconductor H-guide containing optically induced plasma layer have been investigated by utilizing the numerical calculation based on the exact guidedwave theory. The mechanism of high-speed transition from guided modes to leaky waves has been shown with the numerical example of dispersion curves. First we derived the solution to the complex eigenvalue equation by Muller method, and then obtained the complex propagation constant and wave numbers for each direction. With the calculated power flow vectors, the property of leaky waves was revealed graphically. From the figures of the vector form of leaky waves, we found that the direction of average power density drastically changed with the plasma density due to illuminating intensity and also with the operating frequency. In this research we obtained the basic data for designing the leaky wave antenna using a silicon H-guide in the range between 26.5 and 40GHz. We also calculated the propagation characteristics for GaAs as a semiconductor inserted into the H-guide, which was expected to be fast response, and for higher frequency range such as 60GHz that was promising for a practical use. As an experimental trial, we measured the leaky wave radiating from the horn of H-guide, and examined the directivity characteristics due to the illuminating intensity.Some differences between the measurement and the theoretical results have been left at this stage, and their improvement for the experimental conditions are the following assignment.