• International Journal of Contents
• /
• v.8 no.3
• /
• pp.100-104
• /
• 2012

In this paper, a unit cell for low pass filter design by using composite right and left-handed transmission line in conductor-backed coplanar waveguide is proposed. The characteristics of the unit cell are analyzed in order to design a low pass filter in small sizes. By changing the sizes of the unit cell, the parameters of right-handed and left-handed immittance components are changed and the desired characteristics of the unit cell are achieved. The equivalent circuit of the unit cell is extracted and analyzed either. As a result, the simulation results of the unit cell and the equivalent circuit are almost identified. The movement and energy distributions of electromagnetic field are shown to confirm the property of the unit cell. In the end, a low pass filter is demonstrated by cascading three proposed unit cells, which shows cutoff frequency of 1.53GHz and deep attenuation from 2.23GHz to 4.49GHz lower than -50dB.

• Journal of electromagnetic engineering and science
• /
• v.14 no.4
• /
• pp.387-392
• /
• 2014

In this paper, a size-reduced Wilkinson balun with wide harmonic-suppressed band is presented. An accurate analysis of the parallel coupled line with an open stub (PCL-OS) is carried out. The PCL-OS structure shows excellent low pass filter and harmonic-suppression characteristics, which is useful for designing a low pass filter unit cell (LUC) with a reduced size. The designed Wilkinson balun at a 2.45 GHz center frequency not only shows an excellent harmonic suppression including the 5th harmonics up to 14 GHz over 15 dB, but it also has an area reduced to 48% of the conventional one.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.11
• /
• pp.960-965
• /
• 2015

In this paper, a coupled line directional coupler using an LUC(Low-pass filter Unit Cell) of artificial transmission line is presented. The conventional coupled line coupler is limited in length by the ${\lambda}/4$ transmission line while the proposed coupling structure is implemented smaller than $90^{\circ}$ by inserting the phase delay line between two coupled line, reduced in physical size by configuring a phase delay line with an LUC having the characteristics of a typical transmission line in a particular frequency. A coupler having -10 dB coupling factor at the center frequency of 700 MHz is designed, fabricated. The measured result agrees well with that of conventional one. The length of the fabricated coupled line coupler has about 45 % in length compared to the conventional one.

• Journal of the Optical Society of Korea
• /
• v.19 no.6
• /
• pp.673-678
• /
• 2015

Terahertz dual-band frequency selective surface filters made by perforating two different rectangular holes in molybdenum have been designed, fabricated and measured. Physical mechanisms of the dual-band resonant responses are clarified by three differently configured filters and the electric field distribution diagrams. The design process is straightforward and simple according to the physical concept and some formulas. Due to the weak coupling between the two neighboring rectangle holes with different sizes in the unit cell, good dual-band frequency selectivity performance can be easily achieved both in the lower and higher bands by tuning dimensions of the two rectangular holes. Three samples are fabricated, and their dual-band characteristics have been demonstrated by a THz time-domain spectroscopy system. Different from most commonly used metal-dielectric structure or metal-dielectric-metal sandwiched filters, the designed dual-band filters have advantages of easy fabrication and low cost, the encouraging results afforded by these filters could find their applications in dual-band sensors, THz communication systems and other emerging THz technologies.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.5
• /
• pp.424-429
• /
• 2016

This paper presents dual-mode ring-resonator bandpass filter using LUC of artificial-transmission-lines. The conventional ring-resonator bandpass filter has limitation in miniaturization because the conventional ring-resonator is based on a one wavelength operation, and problem due to undesire harmonics. The ring-resonator bandpass filter is miniaturized and show higher order mode rejection by configuring a ring-resonator with LUC of artificial-transmission-lines. The two-stage bandpass filter is designed and fabricated with a ring-resonator and input/output interdigital coupled line. A fabricated filter shows dual-mode, rejection of whole ultra wide band, sharp skirt characteristics and has ring area reduced by 60 % compared to the conventional ring-resonator bandpass filter.