Radio frequency (RF) signal is very mercurial by nature. It’s great at traveling long distances like AM/FM or satellite radio, but it’s also highly susceptible to noise and attenuation. Literally, anything under the sun can affect RF hence adversely hampering any radio communication. Let’s take your typical ambulance as an example. In rural areas, you’re dealing with distance from the source whether it’s a cell tower or another radio. In urban areas, it’s vehicle material like metal. And yes, metal has the most adverse effects on RF. Other electronics emit noise which can affect RF signal. But it’s not just the vehicle but its surroundings, too. High structures, concrete, brick, metal, and glass can weaken RF signal.