Design of a Radio-Frequency Multiplexer, Used in Radiolocation of 802.11 Wireless Sources

This is the second in a series of articles describing the prototype of an 802.11b radiolocator. This device can determine the spatial direction from which every individual data packet has arrived, at a speed equal to the rate of wireless network traffic. The radiolocation method is based on rapid sampling of signal strengths from an array of stationary antennas, during the preamble of a wireless packet. Central to the apparatus is a 16-fold multiplexer, which operates at the passband 2.4-2.5 GHz and the sampling rate of 120 KHz. We describe the design details and the characteristics of the multiplexer at length, with a view towards making this radiolocation technology available in commercial wireless equipment, allowing it to become a standard part of wireless infrastructure.