This document describes the design of a low-cost 60 GHz switched-beam smart antenna receiver subsystem based on substrate integrated waveguide (SIW) technology. Key elements of the design include:
1) An integrated antenna array, Butler matrix, and bandpass filter fabricated on a single substrate to overcome interconnection challenges at millimeter-wave frequencies.
2) A sub-harmonically pumped mixer that downconverts 60 GHz signals to an intermediate frequency of 1.5 GHz using a lower-cost 30 GHz local oscillator instead of a 60 GHz LO.
3) A digital signal processing system that compares the four intermediate frequency signals to determine the maximum power and switch the antenna beam accordingly to track the incoming