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Start Here: The Electricity Behind Radio🔗

Beginner

The first page to read on this site. No prior knowledge required.

A radio signal is alternating current: the same current that flows in a flashlight, except that it reverses direction millions of times a second and leaves the antenna as a wave. Every idea in amateur radio, from antennas to propagation to the power limits in the regulations, is built on a handful of facts about electricity.

Those foundations live on this site's sister site, Exploring Electronics, so they're written once and shared rather than repeated here. Read them first, in the order below, and everything on this site will make sense the first time.

The path from electricity to radio, as a transit map A transit map of the path from electricity to radio. The amber Foundations line on Exploring Electronics runs through stops 1 to 9: conductors, prefixes, voltage, current, resistance, Ohm's law, fuses, series and parallel, and batteries. At Ohm's law the purple AC and fields line branches off through stops 10 to 13: AC vs DC, magnetism, capacitors, and inductors. At series and parallel the green Components line branches off through stops 14 to 18: resistor types, diodes and LEDs, transistors, vacuum tubes, and voltage regulators. The purple and green lines meet at the Radio Fundamentals interchange, where the blue Radio line on this site begins, running on to antennas and feedlines, propagation, and on the air. Every written stop is a link to its article. Click any stop to open its article Radio Fundamentals decibels, reactance, resonance 1. Conductors, on Exploring Electronics 1 Conductors 2. Prefixes, on Exploring Electronics 2 Prefixes 3. Voltage, on Exploring Electronics 3 Voltage 4. Current, on Exploring Electronics 4 Current 5. Resistance, on Exploring Electronics 5 Resistance 6. Ohm's Law, on Exploring Electronics 6 Ohm's Law 7. Fuses, on Exploring Electronics 7 Fuses 8. Series & Parallel, on Exploring Electronics 8 Series & Parallel 9. Batteries, on Exploring Electronics 9 Batteries 10. AC vs DC, on Exploring Electronics 10 AC vs DC 11. Magnetism, on Exploring Electronics 11 Magnetism 12. Capacitors, on Exploring Electronics 12 Capacitors 13. Inductors, on Exploring Electronics 13 Inductors 14. Resistor Types, on Exploring Electronics 14 Resistor Types 15. Diodes & LEDs, on Exploring Electronics 15 Diodes & LEDs 16. Transistors, on Exploring Electronics 16 Transistors 17. Vacuum Tubes, on Exploring Electronics 17 Vacuum Tubes 18. Regulators, on Exploring Electronics 18 Regulators Antennas & Feedlines Propagation On the Air, on Exploring Radio On the Air Exploring Electronics Foundations line AC and fields line Components line Exploring Radio open stop: still being written
Three lines on Exploring Electronics meet at Radio Fundamentals, where this site's line begins. Every filled stop is a link, and the numbers match the table below.

The Foundations, in Order🔗

Each article stands on its own, but they're written to be read in this order. The last column gives the Basic Qualification exam topics each one covers, by their question-bank number (the B-005-002 questions, for example, are about conductors, insulators, and current).

# Read Why it matters for radio Exam topics
1 Conductors, Insulators, and Semiconductors why antennas are copper and their insulators are ceramic B-005-002
2 Metric Prefixes and Units every frequency is in kilo-, mega-, or gigahertz; every capacitor in micro- to picofarads B-005-001
3 Voltage the push behind every signal, and what electromotive force (EMF) means B-005-002, B-005-013
4 Current what flows in an antenna, and why current is what hurts B-005-002, B-005-013
5 Resistance and Conductance feedline loss starts here, and the exam asks about conductance B-005-002
6 Ohm's Law and Power transmitter power, dummy loads, and the power-law questions B-005-003, B-005-004, B-005-006
7 Open Circuits, Short Circuits, and Fuses why a radio's power cord is fused, and what a blown fuse is telling you B-005-003, B-003-019
8 Series and Parallel Circuits combining resistors, and how a supply shares out its voltage B-005-005
9 Cells and Batteries powering a handheld or a portable station, and battery safety B-003-016
10 AC vs DC frequency, hertz, sine waves, and RMS: the language of every radio signal B-005-007
11 Magnetism and Electromagnetism coils, transformers, and the fields that become radio waves B-005-011
12 Capacitors stored charge, the RC time constant, and why a capacitor passes AC but blocks DC: half of every tuned circuit B-005-009
13 Inductors coils, what sets their inductance, chokes, and the other half of every tuned circuit B-005-009
14 Resistor Types colour codes, tolerance, temperature coefficient, and non-inductive loads B-004-006
15 Diodes and LEDs reverse-polarity protection on a radio's power lead, rectification, Zeners, and detection B-004-002
16 Transistors bipolar and field-effect transistors as switches and amplifiers: gain, distortion, and oscillation B-004-001, B-004-003, B-004-004
17 Vacuum Tubes cathode, grid, and plate; why a triode resembles a FET, and why high-power amplifiers still use tubes B-004-005
18 Voltage Regulators the four stages of a linear power supply, why the regulator needs a heat sink, and linear versus switching supplies (and their noise) B-003-008, B-003-017

Two more are useful whenever you're ready: How to Read a Schematic, since radio circuits are drawn the same way, and Resistor Color Codes, for the exam's colour-band questions (also B-004-006).

If you'd rather see the whole picture on one page before diving in, What Is Electricity? is a short overview of the first six.

What Comes Next, and What's Still Being Written🔗

The rest of the Basic syllabus's electronics sections are radio-specific, so they live on this site, in the Radio Fundamentals topic, and all four are ready: What Is a Radio Wave? picks up where AC vs DC leaves off, with wavelength, the radio spectrum, phase, and harmonics (B-005-007), Decibels covers gain, loss, and S-meters (B-005-008), and Reactance and Impedance puts numbers on how coils and capacitors treat each frequency (B-005-010), and Resonance and Tuned Circuits shows how a coil and capacitor pick out one frequency (B-005-012). Radio Fundamentals lists them all.

Also ready now:

  • Getting Licensed: every regulation on the Basic exam, in six articles, from getting your certificate to putting up an antenna.
  • The Amateur's Code: the two short codes of conduct every operator is expected to follow.
  • The ISED Basic Qualification Anki deck: all 984 exam questions as flashcards, organized by syllabus section. Drill each section's cards after reading its articles, not before.

Further Reading🔗