Fumiki Onoma

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We report simultaneous observations of atmospheric gravity waves (AGW) in OI (557.7 nm) and OH air-glow images and VHF radar backscatter from field-aligned irregularities (FAI) in the E-region during the SEEK-2 (Sporadic-E Experiment over Kyushu 2) campaign period from 29 July to 9 August 2002. An all-sky imager was operated at Nishino-Omote (30.5 • N,(More)
A 0.4-5.8 GHz high linearity SiGe-MMIC quadrature-modulator (Q-MOD) having a novel self mixer current control circuit is described. This control circuit, which consists of an output power detector and an envelope current feedback circuit, is applied to unit mixers, and it automatically controls the mixer current according to the output power level. As a(More)
A low spurious SiGe-MMIC direct conversion transceiver using 2f<sub>LO</sub> LO switching configuration for cognitive radio is described. In the proposed configuration, LO signals for Tx and Rx blocks are generated by frequency divider behind switching circuits. By applying this configuration to the transceiver, the offset frequency of maximum Tx spurious(More)
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