Formula collection for radio and RF engineering
All key equations for exam and practice in one place – and a calculator for each that shows the result with worked steps. From voltage and current to decibels and resonant circuits, antennas and propagation.
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What the page does
- Basics: Ohm's law, power, series and parallel circuits
- Wavelength, frequency and decibels
- Resonant circuit, Q factor, filters
- Antennas, transmission lines, matching
- Propagation: radio horizon, Fresnel zone, free-space loss
Background
The resonant frequency of an LC circuit follows from Thomson's formula f = 1 / (2π √(L C)). Power ratios are given in decibels: 10 log₁₀(P₂/P₁) dB; 3 dB is about double the power, 10 dB ten times. dBm refers to 1 mW: 0 dBm = 1 mW, 30 dBm = 1 W.
In practice
How it works: find the formula, enter values and read the result with worked steps. Units are carried along so kilo, mega and micro errors do not creep in. Many formulas have an exercise and an animation. If you are studying for the exam, still work the key equations by hand at least once.
Frequently asked questions
Are the formulas exam-relevant?
The collection covers the usual technical exam topics; the official question catalogue is authoritative.
Can I print the formulas?
Yes, the page can be printed from the browser.