Which type of building material causes the most attenuation of Wi-Fi signals'?

When conducting a site survey for a possible WLAN redesign, you use two Wi-Fi USB adapters for RSSI data collection and two USB spectrum analysis adapters for RF spectrum data. Since your laptop lacks enough USB ports, you connect them via a 4-port powered USB 3.0 hub. What issue could the use of USB 3.0 cause that might impact your site survey?

Your customer's 802.11n laptops are not able to see the SSID in the 5 GHz band in the conference room.
When doing a walkthrough using one of
these laptops, you confirm that it is unable to see the SSID in the 5 GHz band in the conference room. When using your own 802.11 ac laptop, you're able to see the SSID. What is the most likely cause of this problem?

Why does a frame transmitted at 1 Mbps have a greater usable range than the same frame transmitted at 54 Mbps?

You are on site, planning a network at a freight shipping company on a busy harbor. Since the preliminary WLAN design specifies support for the 5 GHz spectrum, you would like to test for radar pulses to determine if DFS channels should be supported at this facility. As a part of your spectral survey with a laptop-based analyzer, you include DFS testing to identify the presence of radar. This is done by manually observing Real-time FFT, Duty Cycle, and Active Devices charts of the spectrum analyzer software.
What potential drawback is present with this DFS test method?