Radio

The invisible architecture of electromagnetic waves.

Core Areas

Area Topics

Amateur Radio

Licensing, bands, modes, digital, emergency comms

RF Theory

EM waves, antennas, transmission lines, propagation, modulation

Ionospheric Science

Layers, HF propagation, solar activity, space weather

Equipment

Transceivers, antennas, SDR, test equipment

Operating

DX, contesting, satellites, EME

Projects

Antenna builds, homebrew equipment

Why Amateur Radio?

Amateur radio combines:

  • Science — RF theory, propagation, ionospheric physics

  • Engineering — antenna design, equipment building

  • Service — emergency communications, public service

  • Adventure — DX contacts, rare stations, propagation hunting

  • Community — global fellowship of operators

The Ionosphere

HF radio depends on the ionosphere — layers of ionized atmosphere that refract radio waves back to Earth:

                    ┌─────────────────────────────────────┐
  300+ km ────────►│           F2 Layer                  │ ← Primary HF reflection
                    ├─────────────────────────────────────┤
  200 km ─────────►│           F1 Layer                  │ ← Daytime only
                    ├─────────────────────────────────────┤
  100 km ─────────►│           E Layer                   │ ← Sporadic E
                    ├─────────────────────────────────────┤
   60 km ─────────►│           D Layer                   │ ← Absorbs, daytime only
                    └─────────────────────────────────────┘
                                    │
                    ┌───────────────▼───────────────┐
                    │         Earth Surface          │
                    │     TX ═══════════════ RX      │
                    └────────────────────────────────┘

Bands & Propagation

Band Frequency Propagation Characteristics

160m

1.8 MHz

Ground wave, night skywave

80m

3.5 MHz

Regional night, some DX

40m

7 MHz

Reliable day/night, excellent DX

20m

14 MHz

Primary DX band, daytime

15m

21 MHz

Daytime, solar cycle dependent

10m

28 MHz

Sporadic E, F2 at solar max

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