Aspects of the subject disclosure may include, generating, by a first hollow waveguide coupled to a first dielectric coupler, a first electromagnetic wave that couples onto a transmission medium, generating, by a second hollow waveguide coupled to a second dielectric coupler, a second electromagnetic wave that couples onto the transmission medium, combining the first electromagnetic wave and the second electromagnetic wave combine to form a combined electromagnetic wave that propagates along the transmission medium without requiring an electrical return path, and adjusting a first phase of the first electromagnetic wave, a second phase of the second electromagnetic wave, or both to adjust a wave mode of the combined electromagnetic wave. Other embodiments are disclosed.