Characteristic impedance of a TEM transmission line with non standard inner conductor

The characteristic impedance of a TEM air-dielectric transmission line has been found for non-standard inner conductor situated inside an outer rectangular conductor or between two parallel plane outer conductors. Examples of diagrams of electric field distributions for cross-sections of the line for different parameters of the inner conductor and a graph of the characteristic impedance of the line versus these parameters are given. They are obtained using numerical techniques to solve the boundary value problem for this line. The line has good properties in comparison to other TEM type transmission lines.