Time-domain receiving properties of a multimode cylindrical waveguide antenna

The time-domain receiving properties of a multi-mode cylindrical waveguide antenna are investigated. The configurational properties of the antenna are characterized by the time-domain scattering matrix that interrelates the time-domain amplitudes of the axial modal constituents traveling towards and away from the radiating aperture of the waveguide, which is taken as their reference plane. The excitation of the system by an incident field is expressed as an excitation integral over the aperture that results from the application of the pertaining time-domain Lorentz reciprocity relation of the time-convolution type. Numerical results illustrate the complexity of the changes in pulse shape (with the associated loss of signal integrity) that occur upon the coupling of the incident wave to the different modal constituents.