Jae-Jin Koo

Soonchunhyang University, Asan, South Chungcheong, South Korea

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Publications (5)0 Total impact

  • Source
    Conference Proceeding: An Active Resonator Using Defected Ground Structure with Islands
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    ABSTRACT: A new resonator using active device and defected ground structure with islands (DGSI) is proposed. The active device is used for supplying the negative resistance which is one of key factors of the proposed active resonator. The negative resistance is realized by the series active device. The electrical characteristics of the proposed resonator with DGSI are improved by combining the negative resistance and the microstrip line with DGSI where the electric field is the most strong. It is shown that the measured improvement in S21 and Sll of the proposed active resonator with DGSI are 4.55 dB and 0.32 dB, respectively, at the resonant frequency compared to the previous DGSI resonator without active device.
    Microwave Conference, 2007. APMC 2007. Asia-Pacific; 01/2008
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    Article: A Power Divider with Adjustable Dividing Ratio.
    IEICE Transactions. 01/2008; 91-C:389-391.
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    Conference Proceeding: A new DGS unequal power divider
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    ABSTRACT: An unequal Wilkinson power divider having rectangular-shaped defected ground structure (DGS) is proposed. DGS microstrip line adopted for the divider is composed of double-layer substrate which removes the ground problem of the previous DGS structures in packaging. The first layer includes DGS on the bottom ground plane. The second substrate of which top metal plane has been removed is attached to the bottom plane of the first layer. At first, a conventional DGS unequal Wilkinson power divider is designed according to the previous method on the first layer, and the second substrate is attached. The proposed DGS with double-layer substrate is described in detail and applied to 1:4 unequal dividers as an application example. The measured unequal Wilkinson power divider has an excellent agreement between prediction and measurement.
    Microwave Conference, 2007. European; 11/2007
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    Conference Proceeding: An Unequal Wilkinson Power Divider with Variable Dividing Ratio
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    ABSTRACT: In this paper, an unequal 1:N Wilkinson power divider with variable power dividing ratio is proposed. The proposed unequal power divider is composed of the conventional Wilkinson divider structure, rectangular-shaped defected ground structure (DGS), island in DGS, and varactor diodes of which capacitance is adjustable according to bias voltage. The high impedance value of microstrip line having DGS is going up and down by adjusting the bias voltage for varactor diodes. Output power dividing ratio (N) is adjusted from 2.59 to 10.4 for the unequal power divider with 2 diodes.
    Microwave Symposium, 2007. IEEE/MTT-S International; 07/2007
  • Conference Proceeding: A 800- to 3200-MHz Wideband CPW Balun Using Multistage Wilkinson Structure
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    ABSTRACT: A novel ultra-wide band CPW (coplanar waveguide) balun having the structure of multistage Wilkinson power divider is proposed. It has an 180deg phase inverting structure between signal line and ground planes of CPW transmission line. The 3-stage Wilkinson power divider is transformed directly into the ultra-wide band balun without any cost of the size and performances. The measurement shows the right S-parameters as a power divider and the proper out of phase as a balun. The measured amplitude and phase unbalances at output ports are plusmn 0.5dB and plusmn 6deg, respectively over 800~3200MHz, while the maximum insertion loss is 0.8dB
    Microwave Symposium Digest, 2006. IEEE MTT-S International; 07/2006