Basic Wireless Switch/transmitter help

Hello I'm new to the site and I’m looking for some help to build a wireless switch. I have a basic understanding of electronics and I’m looking to build a transmitter to send a signal to a receiver to turn on and off a small circuit. It only has to go about 3 feet however it may not always have line of sight. If anyone knows of any schematics or books to help that would be great. The more basic the better I’m more or less trying to understand how it works, however any diagrams of circuits to start with would be much appreciated.

Thanks

Here's an infrared version:

**broken link removed**

This site has a slew of remotely switched circuits Remote Control Circuits, Page 1 #'s-H