# [TECH] Radio & Wireless Communication
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**Radio** is the technology of transmitting and receiving information via electromagnetic waves, enabling broadcasting, wireless telephony, navigation, and radar.
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## Overview
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Guglielmo Marconi (1894–1901) demonstrated long-range radio telegraphy, culminating in the first transatlantic signal (1901). Reginald Fessenden broadcast voice (1906). Edwin Armstrong invented FM radio (1933). The post-WWII wireless revolution expanded from AM/FM broadcasting to cellular phones, WiFi, Bluetooth, and 5G — all electromagnetic wave technologies.
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Radio also underpins GPS, radar, satellite communications, and radio astronomy. The cellular networks of the late 20th century became the substrate for smartphones and the mobile internet.
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## Key Actors
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- **Companies**: Marconi Wireless (1897), RCA (1919), AT&T/Bell Labs, Motorola (1928), Nokia, Qualcomm (1985)
- **Inventors**: Guglielmo Marconi (1874–1937), Nikola Tesla (contested), Edwin Armstrong (1890–1954)
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## Key Patents
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- Marconi, G. UK Patent 12,039 (1896) — wireless telegraphy
- Armstrong, E. US Patent 1,342,885 (1920) — superheterodyne receiver
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## Economic Value
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Global wireless communications market: **$1.5 trillion/year** (2023, GSMA). This includes cellular, WiFi, satellite, and broadcasting. The 5G infrastructure investment alone is projected at $900B globally through 2025.
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## Notes
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GSMA Intelligence *State of Mobile* 2023. 5G investment: Ericsson Mobility Report 2023.
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# Parents
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* [SCI] Electromagnetic Wave Theory⏎