RF PCB Layout: Rules for WiFi, LoRa and Beyond

Above a few tens of megahertz, PCB traces stop being wires and become transmission lines. RF layout is the discipline of managing that reality: controlled impedance, uninterrupted ground. The shortest possible loop between chip, matching network and antenna.
> At a glance: 9 minute guide · part of the PCB design complete guide track · worked example, quick-reference table and field notes included.

## Transmission lines and impedance

A trace over a ground plane has a characteristic impedance set by its width, height above the plane and dielectric. WiFi and LoRa designs use 50 Ω lines — calculate width with a tool or the fab’s stackup, then keep it consistent from pad to antenna.

## The ground plane is sacred

RF return current flows directly beneath its trace. Slots, cutouts and split planes under the RF path turn the layout into an antenna and a detector simultaneously. Stitch ground layers with vias along RF routing and keep the antenna area free of copper pours beneath it.

## Matching networks and components

Series inductors and shunt capacitors match chip to antenna, per the reference design. Use the exact footprint the datasheet gives — a longer pad adds inductance. Keep the whole network within millimetres of the chip, components in the recommended order. Route anything noisy far away.

| Rule | Why it exists |
| — | — |
| 50 Ω controlled trace | Matched energy transfer |
| Unbroken ground under RF | Return path continuity |
| Via stitching | Plane equality at RF |
| Keep-out under antenna | Unperturbed radiation |
| Follow ref layout | Parasitics already tuned |

## How to apply this in your build

Work through the sequence below. Each step assumes the previous one passed. The numbers that need arithmetic are covered by the linked tools at the end of this guide.
1. Copy the module’s reference layout for the RF section literally
2. Calculate trace width for the actual stackup
3. Stitch ground planes along every RF route
4. Reserve a keep-out under and around the antenna

### Worked example

A LoRa node with 8 dB less range than expected traced to a ground stitch row missing under its feed line — adding six vias restored the link budget to datasheet performance. Cross-check with the PCB Trace Width and the result should agree to within rounding.

> Practical note from the bench. RF layout reviews on our bench zoom to the feed line first: stitching and keep-outs there explain most mystery range losses.

## Who this guide is for

First-time readers get a single focused topic instead of a textbook chapter, with every term defined where it first appears. Returning readers use it as a reference. The table, the worked example and the mistake list answer the questions that come up mid-build. If you teach, the structure (theory, application, example, failure modes) maps cleanly onto a lab session.

## Prerequisites and preparation

Before starting. Copy the module’s reference layout for the rf section literally and calculate trace width for the actual stackup. Keep the [PCB Trace Width](/tools/pcb-trace-width) and [Frequency & Wavelength](/tools/frequency-wavelength) open, every number in the worked example is reproducible. Total time including the bench steps: about 7 to 9 minutes.

## Common mistakes to avoid

Each of these has cost real hardware on someone’s bench, usually ours:
– Routing RF over a plane split “just for one crossing”
– Substituting matching passives with different footprints
– Placing the antenna beside a battery or LCD cable

## Key takeaways

– Transmission lines and impedance — the foundation of this guide; revisit it if any measurement here surprises you.
– The ground plane is sacred — the foundation of this guide. Revisit it if any measurement here surprises you.
– Matching networks and components — the foundation of this guide; revisit it if any measurement here surprises you.

### Quick reference card

| Aspect | Where to find it in this guide |
| — | — |
| Core theory | Transmission lines and impedance |
| Application steps | How to apply this in your build |
| Worked numbers | Worked example |
| Failure modes | Common mistakes to avoid |

## How this fits the PCB design complete guide track

This guide is one stop in a structured path. Start from the [PCB design complete guide](/tutorial/pcb-design-complete-guide) pillar page for the full map, or continue with [trace width sizing](/tutorial/pcb-trace-width-guide) and [antenna fundamentals](/tutorial/antenna-basics-tutorial). For the arithmetic, open the [PCB Trace Width](/tools/pcb-trace-width) or [Frequency & Wavelength](/tools/frequency-wavelength).

## Frequently asked questions

Do I need controlled impedance below 100 MHz?
Usually not for hobby layouts — but disciplined grounding still pays at any frequency.

Can I module my way out of RF layout?
Yes — pre-certified modules move the hard RF onto their shielded PCB. Follow their keep-outs and you inherit their performance.

Is there a calculator for this?
Yes, the [PCB Trace Width](/tools/pcb-trace-width) and [Frequency & Wavelength](/tools/frequency-wavelength) run the formulas from this guide instantly, client-side, no signup.

## Where to go next

– The complete pcb design guide: [PCB Design complete guide](/tutorial/pcb-design-complete-guide)
– Read next: [what is vlsi design? building chips with billions of transistors](/tutorial/what-is-vlsi-design)
– Also in this track: [kicad schematic capture: clean beginnings](/tutorial/kicad-schematic-tutorial)
– Continue with: [pcb footprints: pads, courtyards and the checks that matter](/tutorial/pcb-footprint-design-rules)
– Calculate as you go: [PCB trace width calculator](/tools/pcb-trace-width) · [resistor value decoder](/tools/resistor-color-code) · [SMD code decoder](/tools/smd-resistor-code)
– Bookmark this page against the day a measurement surprises you. Most readers return to the table and the mistake list first, and that is the correct order.

## Bench verification habits

Keep a lab notebook entry for every build in this track. The measured values, the deviations from the guide and the reason for each. Six months from now, those notes are worth more than any tutorial. They describe your bench and your components rather than a general case.

When a result here disagrees with your expectation, write down both numbers before changing anything. The gap between predicted and measured is where the real engineering lives. It is usually a tolerance, a parasitic or an assumption that was never checked.
## Formulas and checks from this guide

Verification checklist for this track: run DRC early and often, verify footprints against the datasheet drawing. Walk the return path of every fast signal before ordering. A five-minute Gerber preview has saved more fab cycles than any other habit.

Bookmark this page against your next build in the track. The checklist above is the same one used across 15 guides in this series.

## From our lab notebook

Run DRC continuously, then once more after every final edit. The last small change breaks the most boards.

Two for hobby density, four the moment ground integrity or impedance matters. The cost gap has collapsed.