Disclosed are various embodiments for transmitting guided surface waves of multiple frequencies along the surface of a lossy conducting medium such as a terrestrial medium. Guided surface waveguide probes excite electric fields that substantially mode-match to a guided surface wave mode on the surface of the lossy conducting medium to launch guided surface waves simultaneously or selectively across different operational frequencies. A system and method for guided surface wave transmission comprising a guided surface waveguide probe configured to generate guided surface waves along a surface of a lossy conducting medium at a plurality of distinct operating frequencies; a feed network comprising one or more coils coupled to an elevated charge terminal and one or more compensation terminals; and a plurality of excitation sources configured to energize the feed network at individual operating frequencies. The present disclosure relates to guided surface wave transmission across a lossy conducting medium (e.g., the Earth). Radio frequency (RF) and power transmission via radiating antennas propagate electromagnetic fields that spread geometrically into space and are unrecoverable unless intercepted. In contrast, guided electromagnetic waves are bound to a waveguide structure and propagate as transmission line modes without geometric spreading losses. The guided surface waveguide probe utilizes charge terminals positioned along a vertical axis and an adjustable feed network to synthesize an electric field having a wave tilt angle that corresponds to a complex Brewster angle at a Hankel crossover distance, launching a guided surface traveling wave at one or more selectable or concurrent frequencies.