Dipole field penetration and coupling to a load terminating a coax-fed body of revolution

A method is presented for computing, and an experimental procedure for verifying, the coupling of a signal, to a load impedance terminating a coaxial waveguide whose center conductor protrudes into an open-ended body of revolution (BOR). The excitation is an elementary nearby dipole, which resides on, and oriented normal to the interior BOR surface. To perform this computation directly is very difficult so we resort to an indirect method, which takes the advantage of reciprocity. This allows one to determine the received signal at the coax terminal load from knowledge of the field radiated by a thin-wire monopole mounted on the symmetry axis of the BOR under the condition that the excitation results from TEM wave at the coax aperture. This scheme necessitates the formulation and solution of a simple integral equation. In principle, the approach developed is exact and rigorous, and its validity is demonstrated numerically and experimentally.