STEM与日常科技·英语30篇（3）
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Millimeter-Wave Radar and Sub-Millimeter Velocity Resolution
毫米波雷达与亚毫米级速度分辨率
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Millimeter-wave radar uses frequencies between 30–300 GHz, allowing extremely fine resolution of object motion and position.
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Its short wavelength enables detection of velocity differences as small as 0.1 mm/s—finer than most laser Doppler systems.
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Automotive radars apply this to distinguish a cyclist’s arm movement from a stationary pole at 70 km/h.
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The radar calculates speed by measuring phase shifts in reflected waves across successive pulses.
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Advanced signal processing separates overlapping echoes, even when objects are less than 5 cm apart.
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Unlike optical sensors, mmWave radar works reliably in fog, rain, smoke, or total darkness.
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Medical versions monitor subtle chest movements to estimate respiration and heart rate without skin contact.
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Resolution improves with bandwidth: modern chips offer 4 GHz bandwidth, enabling sub-millimeter accuracy.
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This capability powers gesture recognition in smart home devices and fall detection for elderly care.
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Understanding it reveals why autonomous vehicles rely on radar—not just cameras—for safe decision-making.