Why does USB 3.0 interfere with 2.4GHz devices?

I have read in several product reviews that USB 3.0 ports and hubs can interfere with 2.4GHz devices, including the common Logitech wireless keyboards and pointing devices (mice, trackballs, etc.).

Why does USB 3.0 interfere with 2.4GHz devices?

Where is the real point of interference? Is it from the cables, from the ports, or from the devices?

It boils down to basic shielding and radio interference issues since USB 3.0 creates “noise” in the 2.4–2.5GHz spectrum.

From a white paper titled “USB 3.0* Radio Frequency Interference on 2.4 GHz Devices” written by Intel on the subject:

As previously shown in Figure 2-2, the noise from USB 3.0 data spectrum can be high (in the 2.4–2.5 GHz range). This noise can radiate from the USB 3.0 connector on a PC platform, the USB 3.0 connector on the peripheral device or the USB 3.0 cable. If the antenna of a wireless device operating in this band is placed close to any of the above USB 3.0 radiation channels, it can pick up the broadband noise. The broadband noise emitted from a USB 3.0 device can affect the SNR and limit the sensitivity of any wireless receiver whose antenna is physically located close to the USB 3.0 device. This may result in a drop in throughput on the wireless link.

It basically all comes down to shielding. If the cables and connectors are not properly shielded and a 2.4GHz device is placed nearby, the USB 3.0 signaling can leak and—as a result—interfere with the device.

Here is an illustration from that white paper titled, “Figure 3-1. Radiation from USB 3.0* Channels”; the caption reads, “As an example, an external USB 3.0 hard disk drive (HDD) was used to assess the level of noise that can be radiated from a USB 3.0 device.”