• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.12
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• pp.1316-1324
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• 2009

In this paper, cross-aperture coupled microstrip circular polarization antenna is proposed for 5.8 GHz WLAN(Wireless Local Area Network). A single antenna consists of square patch and slots are located in series feed line with $\lambda_g$/4 phase different which make current direction maximum and minimum repeatedly to generate RHCP(Right Handed Circularly Polarization). We are proposed new structure that removed the section which intersected at a right angle and were composed to four separated slots. The proposed cross slots reduce back lobe of radiation pattern and improve antenna gain. Impedance bandwidth of the manufactured $2\times2$ array antenna is from 5.67 to 5.95 GHz and the maximum radiation gain is 10.59 dBi.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.4
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• pp.257-262
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• 2015

In this paper, the split-ring DGS resonator is proposed and its equivalent circuit are analyzed to design the low pass filter. Compared with the conventional dumbell DGS cell, this structure has a flat fluctuation in low frequency range and a sharp slop at edge frequency. The out-band suppression of the SRR-DGS cell can be improved by placing the open stubs on the conductor line which operates as parallel capacitances. Making use of equivalent circuit analytical method, the characteristics of the improved SRR DGS cell are investigated and applied to design compact low pass filter, which has a low in-band loss, sharp slop and high suppression of more than 35dB within a wide out-band frequency range. The dependence of the transmission characteristic on the dimension of a split ring, such as side-length and split-gap, is analyzed in detail. In addition, an improved SRR DGS cell model with open stubs loaded on the conductor line is then presented to improve the out-band suppression. By using the equivalent-circuit analytical method, an S-band microstrip low-pass filter with perfect low-pass characteristic and high out-band suppression is designed and fabricated.

• Journal of Advanced Navigation Technology
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• v.17 no.2
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• pp.171-176
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• 2013

A microstrip-fed miniaturized folded-slot antenna that is cut at the finite ground plane edge for the size reduction is proposed as a ZigBee module operating in the 2.4 GHz frequency band, as specified by the IEEE standard 802.15.4. The antenna is fabricated within space limited to $35mm{\times}9mm$ on a $35mm{\times}35mm$ substrate, which is about the PCB size of a typical wireless ZigBee module. The measured impedance bandwidth and antenna gain are 2.37~2.49 GHz and 2.4 dBi respectively. The measured radiation patterns are similar to conventional folded-slot antennas and are also stable across the pass band. These properties and its compact structure help in making the antenna suitable for ZigBee module.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.8
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• pp.1292-1296
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• 2002

In this paper, a 3-coupled microstrip line tunable bandpass filter has been designed on the basis of a tonductoriFerroelectricfDielectric (CFD) structure. This tunable filter basically exploits the fact that the increase in the bias voltage leads to the reduction of the effective dielectric constant (eon). This reduced $\varepsilon$eff shifts the center frequency (fc) to the higher value. The characteristics of designed filter are as follows; Return loss (RL) is larger than 10 dB; Insertion loss (IL) is les.i than 3.5 dB: 3-dB bandwidth (BW) is less than 1.18 GHz fc can be tuned from 25.4 GHz to 28.8 GHz over the variation of $\varepsilon$eff, from 10 to 13. Therefore, the tunability comes up to 3.4 GHz. The dimension of the filter designed is 7.0 mm ${\times}$ 5.0 nm ${\times}$ 0.5 mm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.1
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• pp.91-97
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• 2005

In the mobile antenna systems for satellite multimedia communications, the active way antenna having a low sidelobe antenna pattern is described in this paper. This designed and fabricated array antenna is satisfied with international beam pattern regulation on moving states. The subarray of the proposed mobile antenna system is arranged with a stair-planar structure and non-periodic array spacing. This subarray is designed with three-layered microstrip patch as both receiving and transmitting radiator of which are improved with antenna gain and bandwidth. Also, the optimum subarray spacing is designed to make the lowest sidelobe pattern by genetic algorithm. In addition, the characteristics of a GA-perturbed array are investigated from simulated and measured beam pattern results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.12 s.91
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• pp.1178-1183
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• 2004

In this paper, a novel microstrip patch antenna with switchable polarization is proposed. The proposed antenna has a simple structure, consisting of a square radiating patch, a pair of L-type spur-lines, and a microstrip line feed. It can produce either linear polarization or circular polarization by setting the diode on or off From the measured results, low cross polarization levels when operated in the linear polarization, and good axial ratios in the circular state have been observed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.250-256
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• 2008

In this paper, an X-band oscillator is presented using a new miniaturized microstrip hairpin resonator. The newly designed hairpin resonator on the microstrip line employs the spiral structure, which shows a higher loaded quality factor and the 50 % reduced circuit area compared to the conventional one at 9.2 GHz. The oscillator using proposed resonator shows the output power of 10.87 dBm, the second harmonic suppression of 41.99 dBc, and the phase noise performance of -101.49 dBc/Hz at 100 kHz offset, which is better than the conventional resonator oscillator by 6.17 dB.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.1
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• pp.157-165
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• 2012

In this study, a short-wavelength transmission line employing periodically arrayed capacitive devices (PACD) was studied for application to miniaturized on-chip passive component on monolithic microwave integrated circuit (MMIC). The transmission line employing PACD showed shorter wavelength and lower characteristic impedance than conventional microstrip transmission line. The wavelength transmission line employing PACD structure was 8% of the conventional microstrip transmission line on GaAs substrate. Using the theoretical analysis, basic characteristic of the transmission line employing PACD (e.g., loss, effective dielectric constant, effective propagation constant, bandwidth ) were also investigated in order to evaluate its suitability for application to a development of miniaturized passive on-chip components on MMIC. Above results indicate that the transmission line employing PACD is a promising candidate for a development of miniaturized passive components on MMIC.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.2
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• pp.69-74
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• 2000

The bandwidth of microstrip slot antenna with T-shaped feed line was a wider than one of the conventional feeding structure. When the slot antenna with bi-directional radiator wants to radiate only one direction, the reflector must be set up seperately. But this antenna doesn't need set up reflector. And then we proposed to a new method of a directional slot radiator with a cross-shaped feedline including the reflector using 2-layers dielectric materials. It is calculated waves and electric field distribution in the time domain by using FDTD method. We also are calculated return loss, VSWR, input impedance, and radiation pattern in the frequency domain by Fourier transforming the time domain results, respectively. It was found that the bandwidth of this antenna changes as length($\I_s$) and width($\W_s$) of slot, length of the horizontal feedline($\I_d$), length of the vertical feedline($\I_u$) and offset sensitively. After optimizing the parameters of design, the maximum bandwidth was measured as 1,850MHz at the center frequency 2.5 GHz.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.30-36
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• 2009

Various types of ultra-wideband components with 10's of GHz bandwidth have been developed utilizing a uniplanar ultra-wideband balun, which is a simple microstrip-to-coplanar stripline (CPS) transition structure with the operating frequency range from near DC to over 40 GHz. Developed ultra-wideband components include antennas, mixers, doublers, and detectors in a carrier type and in a surface mountable type. One of surface mountable components, for example, single balanced doubler has output frequency 8 ~ 28 GHz. These high-Performance, low-cost ultra-wideband components may replace expensive conventional components, and also can be used to develop new multi-GHz OWE application areas.