It started with a workshop.
Every few months our section at WLD / ON6WL gets together for a hands-on session. Last time, the theme was measuring and analysing our portable setups — antennas, feedlines, connectors, the works. Everyone brought their gear. Someone brought a RigExpert. Someone else had a NanoVNA. Readings appeared on screens. Numbers got written down.
And then came the question that always comes up at some point:
“Wait — what does −3 dB actually mean?”
Why dB Trips People Up
The decibel is one of those concepts that feels mysterious until the moment it clicks — and once it clicks, you wonder why it ever seemed complicated. The problem is that most explanations either skip the basics entirely (“just remember that 3 dB is double the power”) or go straight into logarithm theory that loses half the room in the first paragraph.
What I noticed at the workshop: it was not that people did not understand the physics. It was that they had never seen the maths laid out step by step, at the right pace, with room to practise.
So I built a course.
What the Course Covers
Built for Beginners — But Not Dumbed Down
The course starts with the assumption that you know basic arithmetic and nothing else. By the end, you will be comfortable doing RF chain calculations in your head — the kind that actually come up at a portable setup or during an antenna measurement session.
Each section has exercises with worked answers, so you can check your understanding before moving on. A progress tracker at the top of each page shows you exactly where you are and what is left.
Newly licensed operators who keep seeing dB in specs and want to understand what they are looking at. Experienced operators who learned by doing but never got the theory. Anyone who sat in a workshop, saw a number like
−18.4 dBm, and nodded along when they probably should have asked.
The Cheat Sheet
A taste of what is inside — the four relationships you will use most often:
Available in Three Languages
The course is available in English, Dutch (Nederlands), and French (Français) — switch freely between them at any time. It is completely free, no account required, no strings attached.
73, Kristof — ON3VZ