Radiation from Slot Antennas on Cones Covered by a Plasma Sheath. Volume I. Infinite Cone and Inhomogeneous Plasma

摘要

The radiation from slot antennas on a cone in the presence of an inhomogeneous sheath is treated. The sheath is considered as being made up of a number of conical layers, each of which is homogeneous. The boundary conditions lead to a system of integral equations, which number 4M+4 for a sheath composed of M conical layers. These are reduced to singular integral equations of Cauchy type, which are solved in iterative fashion. For sufficiently fine stratification of the sheath, the first iteration should suffice. In general, fields of both magnetic and electric types are generated in the presence of a sheath, even though only a field of magnetic type may be generated in free space. For a ring slot, however, in which the excitation is azimuthally symmetrical, only a field of magnetic type is generated even in the presence of a sheath. It is shown that the solution for this case forms the basis of the solution for the general case. For thin layers, however, Taylor's series expansions allow all but one of the coefficients to be evaluated in closed form. The far field is found by a multi-dimensional saddle point evaluation. This is illustrated in detail for the free-space case, case, and then the far field patterns in the presence of a sheath are determined. This can be carried out successfully for all components, and to arbitrary orders of iteration. The calculation of input admittance and mutual coupling between transmitting and receiving slots on the cone is formulated and methods of calculation are discussed. (Author)