In this paper we proceed with our investigation of Terahertz emission from beam moving in waveguide structures with dielectric layer [1]. Recently we have considered an open-ended waveguide (with uniform dielectric filling) placed inside regular vacuum waveguide of a larger radius and excited by a single incident waveguide mode [2]. Here we present analytical results for the case where the structure is excited by a moving charge. We also perform simulations using CST® PS code and compare results.