Automotive radar systems typically operate at frequencies around 77 GHz. This frequency range is chosen for several reasons. First, 77 GHz is in the millimeter wave band, which offers advantages such as high resolution and precision in detecting objects at relatively short distances. This is crucial for applications such as adaptive cruise control, collision avoidance and automated braking systems in vehicles, where precise detection and tracking of nearby objects is essential to ensure safety and reliability. Additionally, the 77 GHz band is allocated to automotive radar by regulatory authorities, ensuring compatibility and minimizing interference with other radar systems and communications devices operating in neighboring frequency bands.
In radar systems, frequency is usually expressed in Hertz (Hz), which represents the number of cycles per second. For example, a radar sensor operating at 77 GHz corresponds to a frequency of 77 billion Hertz (77 GHz = 77 × 10^9 Hz). This high frequency allows radar signals to achieve fine resolution in measuring target distances and speeds, making it suitable for applications requiring precise object detection and tracking, such as automotive radar systems.
Radar systems use a range of frequencies depending on their specific application and operational requirements. Common radar frequencies include microwave frequencies ranging from a few gigahertz (GHz) to tens of gigahertz (GHz). The choice of frequency depends on factors such as desired range, resolution, penetration into atmospheric conditions and regulatory constraints. Lower frequencies, such as those around 5 to 10 GHz, are often used in weather radar and marine navigation systems for their ability to penetrate rain, fog, and other atmospheric disturbances. Higher frequencies, such as 24 GHz or 77 GHz, are preferred for applications requiring high resolution and precision in detecting small objects or precise measurement of target speeds, such as automotive radar and surveillance radar systems .
The choice of 77 GHz for automotive radar systems is primarily due to regulatory and technical considerations. Regulatory bodies, such as the Federal Communications Commission (FCC) in the United States and the European Telecommunications Standards Institute (ETSI) in Europe, have allocated the 76-77 GHz band specifically for automotive radar applications. This allocation ensures that automotive radar systems can operate without interference from other radar systems or communications devices operating in adjacent frequency bands. Technically, the 77 GHz radar offers high resolution, precision and reliability in detecting and tracking objects at point-blank range, making it ideal for advanced driver assistance systems (ADAS) and driving technologies autonomous vehicles that rely on precise sensor data for safe and efficient vehicle operation.