Spacetime triangle diagram technique for sectoral horn waveguides

Extension of the STTD (spacetime triangle diagram) technique - a powerful method of solving problems related to generation and propagation of acoustic and electromagnetic signals (finite pulses) - to the case of wave motion within a sectorial waveguide is discussed. The paper shows how a general modal solution, which describes the wave-pulse generation by a source arbitrarily distributed within a sectoral horn, can be constructed for the Dirichlet or Neumann boundary conditions imposed on the horn walls. Providing an exact solution, readily implementable for particular sources using general software packages for scientific computing, the obtained integral formulas represent a powerful tool for analysis of pulsed wave propagation in the sectorial horn waveguides.