Radio Frequency Band

What RF bands are
Wi-Fi’s main frequency bands (2.4, 5, 6 GHz)
UNII sub-bands in 5 GHz and 6 GHz
Channel numbering & widths
Range vs. speed trade-offs
Regulatory aspects (DFS, TPC, etc.)
Summary chart

Table of Contents

1. What RF Bands Are

An RF band is just a range of electromagnetic frequencies (measured in Hertz) used for wireless communication.
For Wi-Fi, these are unlicensed ISM (Industrial, Scientific, Medical) and UNII (Unlicensed National Information Infrastructure) bands, meaning you don’t need a government-issued spectrum license to use them, but you must comply with rules like power limits and interference avoidance.

2. Wi-Fi’s Main Frequency Bands

Band	Typical Wi-Fi Use	Advantages	Disadvantages
2.4 GHz	802.11b/g/n/ax	Long range, better wall penetration	Crowded (Bluetooth, microwaves), only 3 non-overlapping 20 MHz channels
5 GHz	802.11a/n/ac/ax	More channels, higher speed	Shorter range, more DFS restrictions
6 GHz	802.11ax (6E), 802.11be	Huge capacity, low interference	Very short range, new device requirement

2.4 GHz Band

Frequency range: 2.400 – 2.4835 GHz (in most countries)
Channels: 1–14 (14 only in Japan)
Channel spacing: 5 MHz
Non-overlapping 20 MHz channels: 1, 6, 11 (U.S.)
Used since 802.11b in 1999 — very mature but congested.
Interference sources: Bluetooth, cordless phones, microwave ovens.

5 GHz Band

Frequency range: 5.150 – 5.825 GHz (varies by country)
Divided into UNII sub-bands (explained in section 3)
Supports wider channels: 20, 40, 80, 160 MHz
Less crowded than 2.4 GHz, but range is ~30% shorter
Some channels require DFS (Dynamic Frequency Selection) to avoid radar interference.

6 GHz Band (Wi-Fi 6E / Wi-Fi 7)

Frequency range: 5.925 – 7.125 GHz
No legacy devices → clean spectrum
Allows up to 59 channels at 20 MHz each in the U.S.
Ideal for high-throughput, short-range applications (VR, AR, high-capacity APs)
Shortest range due to high frequency and low penetration.

3. UNII Sub-Bands in 5 GHz and 6 GHz

5 GHz UNII Bands

UNII Band	Frequency Range (GHz)	Typical Channels	Notes
UNII-1	5.150–5.250	36, 40, 44, 48	Indoor use, lower power
UNII-2	5.250–5.350	52, 56, 60, 64	DFS required
UNII-2e	5.470–5.725	100–144	DFS required, outdoor allowed in some regions
UNII-3	5.725–5.825	149, 153, 157, 161, 165	Higher power, outdoor allowed

6 GHz UNII Bands (U.S.)

UNII Band	Frequency Range (GHz)	Notes
UNII-5	5.925–6.425	Indoor standard power / low power
UNII-6	6.425–6.525	Indoor low power
UNII-7	6.525–6.875	Indoor standard power / low power
UNII-8	6.875–7.125	Indoor low power

4. Channel Numbering & Widths

20 MHz: Standard width; most channels are defined in 20 MHz increments.
40 MHz: Combines two adjacent 20 MHz channels; doubles throughput.
80 MHz: Common in 802.11ac/ax for high performance.
160 MHz: Very high throughput; fewer non-DFS options in 5 GHz, plentiful in 6 GHz.

Example:

Channel 36 = center frequency 5.180 GHz
Channel 149 = center frequency 5.745 GHz

5. Range vs. Speed Trade-Offs

Lower frequency (2.4 GHz): Travels farther, penetrates walls better, but slower due to narrow channels and more interference.
Higher frequency (5/6 GHz): Higher data rates, more channels, but attenuates faster and has shorter coverage.

6. Regulatory Aspects

DFS (Dynamic Frequency Selection): AP must detect radar signals and move channels if radar is present.
TPC (Transmit Power Control): Limits power output to reduce interference.
Regional differences: FCC (U.S.), ETSI (Europe), MIC (Japan) have different allowed channels and power limits.

7. Summary Table

Band	Freq. Range	Channels (20 MHz)	Pros	Cons
2.4 GHz	2.400–2.4835	1–14	Long range, wall penetration	Crowded, slow
5 GHz	5.150–5.825	36–165	More channels, high speed	Shorter range, DFS needed
6 GHz	5.925–7.125	1–59 (20 MHz)	Huge capacity, low interference	Very short range, new hardware only