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Interactive lesson · Wi-Fi in Every Room

Wi-Fi bands, channels and dead zones

Find the dead zone in a 3D house, watch a live Wi-Fi heat map change as you move the router, pick 2.4, 5 or 6 GHz for each device, add a wired access point and plan clean channels. Free, about 9 minutes.

Pickitech Lab · Wi-Fi in every room · Lesson 1
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Measuring the house…

What you will learn

  • How to read Wi-Fi signal in dBm, and why −67 dBm is the number to aim for.
  • What walls, doors, glass, a refrigerator or an aquarium cost your signal, and where a router should (and shouldn’t) live.
  • When to use 2.4 GHz, 5 GHz or 6 GHz, and why a microwave oven slows 2.4 GHz Wi-Fi.
  • How to add a wired access point: Ethernet run, PoE power, access point mode, one network name, and how roaming really works.
  • How to plan channels: 1, 6 and 11 at 20 MHz on 2.4 GHz, non-overlapping 80 MHz channels on 5 GHz, DFS, and 6 GHz Preferred Scanning Channels.

Key terms

dBm measures signal power. Wi-Fi readings are negative: −50 dBm is excellent, −67 dBm is the usual design target for smooth calls and video, and below about −80 dBm the connection barely works. Every 3 dB lost halves the power.

Dead zone is a spot where the signal is too weak to use, usually because of distance plus walls, metal or water in the way.

2.4 GHz reaches furthest but has only three non-overlapping channels and shares the air with neighbors, Bluetooth and microwave ovens. 5 GHz is faster with many more channels and shorter reach. 6 GHz (Wi-Fi 6E and Wi-Fi 7) adds 1,200 MHz of clean spectrum in the U.S. with the shortest reach.

Access point is a Wi-Fi radio connected to your router by Ethernet. Set to access point mode, it leaves DHCP to the router and broadcasts the same network name and password.

PoE (Power over Ethernet) carries power on the network cable: up to 15.4 W per port with 802.3af, 30 W with 802.3at (PoE+), and 60 or 90 W with 802.3bt.

Roaming is your device moving from one access point to another. The device decides: an iPhone starts looking when its signal drops past −70 dBm.

DFS channels (52 to 144 on 5 GHz) are shared with radar, so an access point must listen before using them and move away if it detects radar.

Quick checks at home

  • Get your router out of closets and cabinets, off the floor and away from the microwave, the refrigerator and big aquariums. Central and a little high is best.
  • Use one network name and password for every band, and 20 MHz channel width on 2.4 GHz.
  • Rooms still weak? A wired access point (or a mesh with Ethernet backhaul) beats a plug-in extender.
  • Several access points? Give neighbors different channels: 1, 6 and 11 on 2.4 GHz, and blocks that don’t overlap on 5 GHz.

The heat map in this lesson is a simulation using typical wall losses and a standard indoor path-loss model. Real homes vary, so measure yours with a Wi-Fi scanner app.

Sources

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