The signal is the product
In RF work, the board is not just a carrier for components — it is part of the circuit. Traces become transmission lines, vias become inductors, and ground pours become the return path for every signal you route.
That change of mindset is everything. At gigahertz frequencies, a wire is a distributed element, and the rules you learned for digital design stop applying.
Impedance matching
Maximum power transfer happens when source, line, and load all sit at the same impedance — usually 50 ohms. A mismatch reflects energy back down the line, costing you power and, worse, distorting the signal.
Control your stack-up so transmission-line impedance is predictable, keep the length and width of matching networks intentional, and verify with measurement rather than simulation alone.
Shielding and grounding
High-frequency circuits both radiate and receive. Shielding cans, solid ground planes, and careful partitioning between analog and digital sections are what keep a sensitive receiver from listening to its own switching noise.
One continuous, low-impedance ground is usually the right call. Splits look tempting but create return-path discontinuities that show up as emissions and crosstalk.
Test early, test often
RF problems are hard to find by inspection and expensive to find in production. Bring up the signal chain in stages — antenna to LNA to mixer to baseband — and characterise each stage before moving on.
A vector network analyser and a spectrum analyser will tell you more than any amount of guessing. Measure, adjust, and measure again.
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