Active integration ring antenna/phase shifter for direct conversions

A compact active ring antenna integrated with diodes for direct conversion, or zero-IF detection, is presented. The circular aperture ring antenna exhibits a wide bandwidth and a high gain performance. The ring can act as a phase shifter to provide the necessary 90° characteristics to operate with I/Q signals for direct conversions. Two Schottky diodes can be connected to the ring structure and are used as a mixer. The authors focus on the case at 2.44 GHz, which is of particular interest for home networking communication systems.