Electromagnetic (EM) waves are indispensable in modern telecommunications. Despite their essential role in modern technology, EM waves are considered to be an abstract concept by many students. In this activity, an inexpensive two-coil system was constructed in a teaching laboratory and used to demonstrate information transfer by non-sinusoidal EM waves. Twenty secondary school students were invited to try out a hands-on activity developed based on this system. The participants were divided into teams, with some members in each team encoding and transmitting a message using EM signals followed by other members receiving the signal and decoding the message. The message was encoded using different frequencies and amplitudes of the sinusoidal components in the EM signal. In this outreach activity, a significant number of participants was found to hold the misconception that all EM waves are sinusoidal. After this hands-on activity, the number of participants holding this misconception decreased.