Frequency band and coupling loss are the two important parameters of leaky coaxial cables with periodic slots. Frequency band can be predicted by analyzing the arrangement of the slots on the outer shield of the cable, but the coupling loss is not so easy to determine by classical methods. In this paper, the finite-difference time-domain (FDTD) method is used to calculate the electric field distribution in the slot cut in the outer conductor of the coaxial cable. The dyadic Green's Function is then used to calculate the radiation field of the equivalent surface magnetic current densities. By these two methods, the coupling losses of the leaky coaxial cables with different periods, sizes and shapes of the slots can be accurately obtained. Some results in this paper were verified by the experimental results of the leaky coaxial cables designed for railway mobile communications with a frequency band of 100-500 MHz.

A new kind of leaky coaxial cable composed of an axially-slotted line covered with periodic metallic patches is proposed. The basic cable sets up a surface wave and does not radiate itself, but excites the patch apertures into radiation. The direction of the radiation field can be changed by adjusting the size and period of the patches according to the environmental application. A combined method that involves FDTD iteration and integration of the equivalent surface magnetic current is introduced in order to determine the radiation field accurately.

When the transmit BJT power amplifier is connected to the receive BJT low-noise amplifier, a switch can be realized. Since the frequency-dependant quarter-wavelength transmission line normally used in low-cost PIN diode switches has been eliminated, the bandwidth is increased.

本文利用第二类尖劈并矢格林函数对任意夹角的V形缝隙天线进行了矩量法计算。V形缝隙开在V形金属板上，并且由双线从中间馈电文中给出了缝隙口而场分布和天线H面方向目的理论计算结果和实验结果，两者基本吻合。文中最后给出了三种非V形弯曲缝隙的实验结果。

在讨论了基于时域有限差分法和完全匹配层技术的数值模拟方法之后，首先从运动电荷和电力线的角度直观地描述了脉冲电磁波的辐射过程，然后进一步从场与电荷相互作用的角度分析了天线上电荷是如何被加速以及如何维持其运动状态的，指出了开放空间中突然出现的时变电场（位移电流）是脉冲电磁波辐射的根本原因。文中还对局部电阻加载的天线和局部弯曲的天线进行了研究，以进一步说明上述观点。对多种情况下的脉冲辐射过程进行了数值模拟，并给出了电场的等高线和空间波形图，这些图形对理解脉冲电磁波的辐射机理非常有益。