{"id": "card_n_a7ae37960cae", "kind": "note", "title": "FM broadcast (VHF) — three-meter waves, line of sight", "body": "88–108 MHz; sealed: the 100 MHz wave is 2.99 m, and its quarter-wave whip is 74 cm —\nthe length of a car antenna, derived: https://narrowhighway.com/s/d6211f4efb2518c6de145decf57f27b131a01c24ce7841853f395b7bc986c323 . VHF barely bends around the Earth, so FM is a\nline-of-sight service: you hear it to the horizon and little farther. Frequency modulation\ncarries the signal in the wave's TIMING rather than its height, which is why amplitude noise\n(lightning, ignition) mostly washes out — the static-resistance is structural, not magic.", "source": {"label": "Concordance assay — 2026-07-09", "url": "https://narrowhighway.com/s/d6211f4efb2518c6de145decf57f27b131a01c24ce7841853f395b7bc986c323", "ref": "spectrum_walk", "authority_tier": "engine_derived"}, "shelf": "science", "box": "radio_spectrum", "bands": ["fm broadcast", "vhf", "88 mhz", "108 mhz", "quarter wave", "car antenna", "line of sight", "frequency modulation"], "connections": [], "author": "engine", "created_at": "2026-07-10T01:06:08.948754+00:00", "updated_at": "2026-07-10T01:06:08.948754+00:00", "visibility": "public", "lifecycle_stage": "public", "volatility": "permanent", "surface": "secular", "metrics": {"paperclips_count": 0, "helpful_count": 0, "not_helpful_count": 0, "cite_count": 0, "walks_through_count": 0, "flagged_count": 0}, "source_hash": "9d3ac4e626aaa1dd48f04a664af205718eb22c137bfb4ae39ead4da22a981e0e"}