There are two well established icons or symbols that are used when we're talking wireless networks. There is a difference between the two. One is the transmitter of a wireless network, the other is a hot-spot of a wireless network.
I've only recently gotten to know databases. How they work, SQL and the different scripts you can use. I love it. I think it's so much fun going into different databases when testing, viewing, comparing, joining and editing them. Even though the amount of trouble you can cause in there is immense.
When drawing and explaining at the same time, it doesn't have to be pretty. It has to be clear. What's important is to capture the essence of the thing you're trying to draw. The essence of a tree isn't it's beautiful and detailed leaves. It's a trunk with two branches. No need to use time on drawing anything else, if people get that what you've drawn is a tree.