Why Wi-Fi Coverage Depends on More Than the Standard – Real RF Measurements

When evaluating Wi-Fi performance, most users focus on the standard: Wi-Fi 5, Wi-Fi 6 or Wi-Fi 7. In practice, however, real coverage and signal quality depend much more on the RF implementation of the device than on the standard itself.

This article presents real transmit power measurements of two ASUS routers across multiple channels. The results clearly show that not all channels – and not all devices – behave the same.

Test Methodology

• Devices under test: ASUS routers, two different models
• Measured parameter: transmit power (dBm)
• Measurement method: RF power measurement using dedicated test equipment
• Frequency range: 5 GHz band, including DFS channels

The measurements were performed in controlled conditions using professional RF measurement equipment. This allows direct comparison between devices and channels.

Measured Results

The table below presents measured transmit power values across multiple channels for both devices.

Figure: Measured transmit power across 5 GHz channels showing differences between devices and the impact of DFS constraints.

Transmit Power Differences Between Devices

The results show significant differences in transmit power between the tested routers. In some cases, the difference reaches several dB.

This is extremely important because even small differences in dB translate into large differences in real signal strength:

• +3 dB ≈ 2× power
• +6 dB ≈ 4× power
• +8 dB ≈ more than 6× power

This means that two routers using the same Wi-Fi standard can provide very different real-world coverage.

Transmit Power is Not Constant Across Channels

Another important observation is that transmit power is not constant across all channels.

Even within the same device, different channels can show noticeably different output power levels.

DFS Channels and Regulatory Constraints

Channels in the DFS (Dynamic Frequency Selection) range behave differently from standard indoor channels.

Some channels may be unavailable or restricted due to regulatory requirements designed to protect radar systems.

As a result, even if a router interface shows that certain channels are available, real RF behavior may be limited.

Router GUI vs Real RF Behavior

The settings visible in the router interface should be treated as preferred, not guaranteed.

Actual behavior depends on multiple factors, including regulations, firmware and RF conditions.

Do Newer Wi-Fi Devices Transmit Less Power?

Long-term observations show that newer Wi-Fi devices do not necessarily transmit with higher power. In many cases, their output is more controlled and optimized.

This means that upgrading to a newer Wi-Fi standard does not automatically guarantee better coverage.

Conclusion

Real Wi-Fi performance depends on RF implementation, not just the standard.

Measured data clearly shows that transmit power varies across devices and channels, and regulatory mechanisms such as DFS have a direct impact on real-world behavior.

For this reason, network design should rely on real measured performance, not only on specifications.