Seong-Sik Jeon

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A wireless sensor server is developed based on a reconfigurable active smart-antenna/retrodirective array. The system can serve as both a retrodirective array transponder and a smart-antenna receiver simply by changing the frequency of the local oscillator applied to the mixers, enabling it to best utilize its hardware to suit its communication environment.(More)
In this paper, a novel design of smart antenna system based on hybrid analog-digital beamforming is proposed. The goal of the design is to construct smart antenna beamforming systems with high data rate throughput. The speed bottleneck in DSP I/O congestion is relieved using analog beamforming at the IF frequency, while the advanced signal processing(More)
This letter presents a high isolation dual-frequency orthogonally polarized rectangular patch antenna utilizing microstrip feed line integrated with a defected ground structure (DGS). The demonstrated approach results in a significant improvement in port isolation in comparison to a conventional dual-polarized antenna fed by simple microstrip lines.(More)
A compact integrated antenna with direct quadrature conversion circuitry for broad-band millimeter-wave communications is proposed. The conversion circuits include two even-harmonic mixers based on antiparallel diode pairs (APDPs). The equivalent circuit of the APDP derived here provides good agreement with the measured data from 17 to 23 GHz. Overall phase(More)
In this paper, a broadband beamforming system for millimeter-wave systems is proposed. DOA is estimated by sampling only part of signal spectrum, thus the beamformer system does not require high speed sampling rate of A/Ds. In addition, I/Q vector attenuation scheme was used for IF weighting process. For the weighting process, a balanced structure of(More)
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