Figure 6.

Various lengths of bare inner conductor (e) of the coaxial coupling probe were investigated, where the coupling gap was fixed as g = 2 mm in this set of simulations. Inset shows the top view of the assembly for the case when e = 7 mm. The bare inner conductor of the coaxial cable is not radiating as a monopole antenna and it does not contribute to the high transmission coefficient (or reduced losses), thus ensuring that the length of the coaxial cable is less than one wavelength (λ), and the length of the bare inner conductor is less than λ/4.