STEM与日常科技·英语30篇（3）

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毫米波雷达与亚毫米级速度分辨率

Millimeter-wave radar uses frequencies between 30–300 GHz, allowing extremely fine resolution of object motion and position.
Its short wavelength enables detection of velocity differences as small as 0.1 mm/s—finer than most laser Doppler systems.
Automotive radars apply this to distinguish a cyclist’s arm movement from a stationary pole at 70 km/h.
The radar calculates speed by measuring phase shifts in reflected waves across successive pulses.
Advanced signal processing separates overlapping echoes, even when objects are less than 5 cm apart.
Unlike optical sensors, mmWave radar works reliably in fog, rain, smoke, or total darkness.
Medical versions monitor subtle chest movements to estimate respiration and heart rate without skin contact.
Resolution improves with bandwidth: modern chips offer 4 GHz bandwidth, enabling sub-millimeter accuracy.
This capability powers gesture recognition in smart home devices and fall detection for elderly care.
Understanding it reveals why autonomous vehicles rely on radar—not just cameras—for safe decision-making.