November 4, 2025, 11:13 am | Read time: 4 minutes
Most cars today can be unlocked and locked with a remote key. For this to work, you need to be within a certain distance of the vehicle. However, there is a way to increase the range.
It’s a simple yet ingenious trick demonstrated by retired physics professor Roger Bowley from the University of Nottingham in a video. To increase the range of his car key’s remote signal, he holds it to his head. And indeed, he manages to unlock his car from a considerable distance. But why does this work?
Overview
Car Remote Key Range Sometimes Falls Short
Many are familiar with the situation: You’ve forgotten to lock your car, but you’re now too far away to do so with the key’s remote signal. Typically, you turn around and walk back to the car. Or, you’ve lost track of your car in the parking lot and want to find it by briefly flashing the vehicle’s lights with the remote key. It’s frustrating when you’re also out of the key’s range for this. This is where the trick demonstrated by Roger Bowley comes in handy.
It is based on simple physical principles. Since 1993, car remote keys have been available that send radio waves to a car’s control unit to lock or unlock it. These keys operate on different frequencies, usually depending on the manufacturer and the vehicle’s country of origin. In North America, car keys typically operate at 315 MHz, while in Europe, the standard is 433.92 MHz (ISM band). Exact range specifications for a remote key cannot be made, as they depend on external conditions and sources of interference.
What is certain, however, is that the range of a remote key decreases the farther you are from the car. Bowley demonstrates this in the video. At a distance of about 15 meters, his car can still be unlocked with the remote key without any issues. However, at around 26 meters, it no longer works. Even with an outstretched arm, the remote signal could not reach the car’s control unit.
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Fluid in the Head Acts as an Amplifier
This is where the trick comes into play: Bowley holds the remote key to his head, and the car responds. According to the professor, this is due to the high fluid content in every person’s head. Water extends the range of electromagnetic waves, like those emitted by remote keys when activated. This is possible because radio waves are generated from an energy source consisting of oscillating magnetic and electric fields. Radio waves radiate outward at the speed of light, with their movement resembling waves in a water basin. The fluid in the head carries electromagnetic waves that operate on the same frequency as the remote’s radio waves. This causes them to add up and increase the range of the car key, Bowley explains.
Holding the car’s remote key to your head is just one option. It’s practical because you don’t need any additional equipment–after all, you always have your head on your shoulders. Skin contact can also increase the range of a car remote key, as it also acts as an amplifier. However, the trick works even better with a canister or a large bottle of water.
Car Remote Key on the Head: Dangerous to Health?
Health concerns about electromagnetic radiation have long been a topic of interest. This mainly involves cell phone or microwave radiation. Remote keys in this country, as mentioned, use a frequency around 433.92 MHz, which falls into the high-frequency range. According to the Federal Office for Radiation Protection (BfS), high-frequency fields can theoretically have health effects on humans if the radiation exposure is prolonged and leads to a thermal effect in the body that it can no longer compensate for. However, certain threshold values must be exceeded to disrupt the body’s heat regulation. In cases like the aforementioned trick, this is not the case, and no consequences are to be feared.