Kyoungkeun Kim

Compact chip monopole antenna with parasitic patch for GPS applications

A chip monopole antenna with a parasitic patch is proposed for GPS applications. To reduce the dimensions of the antenna, the chip monopole antenna is composed of stacked meander, helix structures, and a parasitic patch. The impedance and radiation characteristics of the antenna are investigated. The measured results show that the proposed antenna, having compact dimensions of 3.6 × 5 × 1.3 mm, has a bandwidth of 60 MHz (1.53–1.59 GHz) and a maximum radiation gain of 0.53 dBi.

Dual-band filter using half wavelength resonators and dual-mode resonator

In this paper, the design and the fabrication of dual bandpass filter with controllable bandwidth is presented. Two resonators are designed to have different fundamental resonant frequencies, one for the lower passband and the other for the upper passband. A lossless transmission line model is used to determine the resonance properties of the resonator and the external quality factor. In the upper band, a dual-mode resonator was used for adjusting bandwidth. Proposed dual band filter at passband center frequency 2.45/5.25 GHz is designed and fabricated.

Compact dual-mode interdigital-loop resonator and filter application

A novel compact dual-mode resonator is proposed. This proposed dual-mode resonator was composed of the following features: the series capacitance is inserted for miniaturization and its effect was also analyzed, and open stub was applied on symmetric plan for dual-mode behavior. Using this dual-mode resonator, dual-band bandpass filter of 0.2 λg by 0.28 λg (at odd mode resonance) for WLAN application was designed and fabricated providing an excellent verification on the attractive features of the filter, such as compact size and extra transmission zeros without increase order of filter.

A Design of the Dual-Band Bandpass Filter Using a Coupling Controllable Dual-Mode Resonators

In this paper, we designed and fabricated a dual-band bandpass filter which can control upper and lower bandwidth using the transformed E-shaped dual-mode resonator. The filter is made the coupling between even-mode not to affect odd-mode resonant frequency by the transformed resonator to control upper bandwidth effectively. The cross coupling between input and output feed lines was employed to improve stopband characteristic. The bandpass filter has been designed to indicate the same bandwidth at center frequency 2 GHz and 3 GHz to show to control bandwidth.

Compact Dual-Band Bandpass Filter Using Two Dual-Mode Resonators

In this paper, the design and the fabrication of dual-band bandpass filter using two dual-mode resonators is presented. Dual-mode resonator using a short stub is miniaturized by inter-digital capacitor and stepped impedance. Two dual mode resonators are designed to have different resonant frequencies, one for the lower passband and the other for the upper passband. Transmission zero is positioned at low or high rejection bands with a sharp skirt characteristic. Dual-band operation can be achieved using dual feeding structure. For WLAN, the proposed filter at 2.45/5.25 GHz is designed and fabricated. The size of the filter is as compact as 1.

Dual-Band Filter Using Heterogeneous Resonators

In this paper, the design and the fabrication of dual bandpass filter using heterogeneous resonators is presented. Each resonator would not have an effect on each resonant frequency. Two types of resonators are designed to have different fundamental resonant frequencies, one for the lower passband and the other for the upper passband. In the lower band, half and quarter wavelength resonators were used. In the upper band, a dual-mode resonator was used for adjusting bandwidth. In the upper pass band frequency, resonators of lower passband acts as the input and output. For WLAN, Proposed filters with different second passband frequencies at 2.45/5.2 GHz and 2.45/5.8 GHz are designed and fabricated.

Composite Right/Left Handed(CRLH) Transmission Line with Controllable Transmission Zeros

In this paper, a novel CRLH-TL unit cell with controllable transmission zeros was proposed. Proposed composite right/left handed transmission line(CRLH-TL) unit cell is implemented in the form of the metal-insulator-metal(MIM) capacitors, the microstrip stub inductors, and the co-planar waveguide(CPW) inductor. And this proposed CRLH-TL generates two transmission zeros in lower/upper passband by the effort of electromagnetic couplings between each MIM capacitors and microstrip stub inductors. Using this proposed CRLH-TL, broad bandpass filter for UWB system was designed and fabricated. The measured results reveal that the two transmission zeros are observed in lower/upper passband and the overall size of the filter, excluding the feed line is about 8 mm8 mm, less then /4 on electric size.

Stacked lowpass filter using LTCC technology

In this paper, the design and fabrication of stacked lowpass filter in a low temperature co-fired ceramic (LTCC) technology is presented. The equivalent circuit of lowpass filter is evaluated by microwave network analysis. It is shown in this paper that the filter schematic is built on a coupled line and multi-layer electric coupled structure. The proposed LPF passes GSM band and rejects USPCS, IMT2000, WiBro, Bluetooth/WLAN, satellite DMB. The dimensions of fabricated LTCC lowpass filter are 3.5 mm x 4 mm x 0.33 mm. The proposed filter has been implemented in a five-layer ceramic substrate.