The paper presents the results of studying the behavior of ultrashort pulses in multiwire structures with inhomogeneous dielectric filling. Five different versions of the structures where the modal phenomena may appear have been investigated. These phenomena may be a reason why the safety devices malfunction, or, on the contrary, can be used as a protection against electromagnetic interference. Several variants of creating the modal antipodes have been studied. This may be achieved by the following: changing the location of the conductors in the middle layer of the multilayer printed circuit board; changing the permittivity of the environment; increasing the dielectric layer thickness; filling the internal cavities with the dielectric; changing the location of the conductors in the cable.