As always, it's wise to get a complex project going one step at a time. Here is a WiFi RSSI indicator, the basis of a project for the future relating to RF exposure.
What was to be a simple horizontal bar-graph with one bar allocated for each channel, became complicated when I found there were several networks broadcasting on the same channel. Accordingly, the design was revised to list each unique network's RSSI bar in order down the page.
Code, but no detailed instruction for this project, is available at www.excelworks.info