band of 9.50 to 14.0 GHz and the imaginary part is close to zero.
Since, the calculated input impedance of the TEM horn antenna is
about 40 Ω, the TEM double-ridged waveguide is designed for a 40 Ω
characteristic impedance to obtain low levels of VSWR throughout
the transformation from the TEM-mode in the coaxial section to the
TEM-mode in the parallel plate waveguide.