In this paper, a low complexity microwave based direction finding (DF) system is presented. The proposed system consists of single six-port (SP) circuit integrated with a reconfigurable multiple-input-multiple-output (MIMO) antenna system. The SP circuit covers a wide frequency band (1.68∼2.25 GHz). The SP circuit is also characterized for phase error compensation caused by the slight asymmetry of SP and power detectors. The reconfigurable MIMO antenna system used is compact design, covered several well-known wireless standards between frequency bands from 0.7 GHz to 3 GHz. The SP circuit is integrated with reconfigurable MIMO antenna system to form complete beam forming mode for second generation cognitive radio (CR) platforms. The proposed design is a complete integrated solution with DF capabilities for CR platforms. The design is suitable to be used in compact wireless handheld and mobile communication devices. The fabricated integrated system achieves ±16o accuracy in its direction of arrival estimates.
Key words: Microwave DF, Six-Port circuit, Beamforming mode, Reconfigurable MIMO Antenna, Cognitive Radio Platforms
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