My favorite propane tank.
Intermodulation occurs when two or more signals mix generating a new or modified signal. Launched in 1999, the Intermod Series engages through interference. Methods of propagation include altering the electromagnetic field surrounding the electric-power grid, FM radio and boosted CB radio transmissions, launching rockets in the city to alter the atmosphere, and a spotters’ skywatch network and purging event. Developed to have the potential for interaction, the projects are free and distributed with 1-800 numbers, embroidered patches and stickers, radio monitoring frequencies, or online forums and journals.