• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.2
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• pp.224-227
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• 2016

This paper proposes a design of W-band mm-wave wideband monopulse comparator using waveguide structure for applications. The main idea of proposed design is to combine a self-compensating phase shifter on $90^{\circ}$ hybrid for wideband $180^{\circ}$ hybrid. Using multiple conventional phase shifters, because of their narrow-band characteristics, tends to restrict working bandwidth of system including antennas. Proposed comparator could relieve the problem since it applies the self-compensating phase shifter. The comparator has waveguide structure so it shows excellent characteristic in loss. It also show wideband characteristic in amplitude and phase response between ports.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1098-1106
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• 2007

This paper presents active antenna diplexers implemented into an ultra-wideband CPW(Coplanar Waveguide) fed monopole antennas. The proposed active antenna diplexer is designed to direct interconnect the output port of a wideband antenna to the input port of two active(HEMT) devices, where the impedance matching conditions of the proposed active integrated antenna are optimized by adjusting CPW(Coplanar Waveguide) feed line to be the length of 1/20 $\lambda_0$(@5.8 GHz) in planar type wideband antenna. The measured bandwidth of the active integrated antenna shows the range from 2.0 GHz to 3.1 GHz and from 5.25 GHz to 5.9 GHz. The measured peak gains are 17.0 dB at 2.4 GHz and 15.0 dB at 5.5 GHz.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.4
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• pp.347-351
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• 2008

In this paper, a new co-planar waveguide ultra-wideband aperture is designed as wireless application in ships. The designed antenna consists of a rectangular aperture on a determined ground plane and a mushroom shaped stub. The mushroom-shaped stub, which is simple, convenient to analyze and optimise, has less parameters. This antenna has compact aperture size $21.1{\times}8.1mm^2$, designed on FR-4 substrate with dielectric constant of 4.3, thickness of 1.5mm. CPW fed planar antenna has the advantages of wide-bandwidth, low-cost and easy interaction with the radio frequency front end circuitry.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.2
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• pp.147-156
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• 1996

In this paper we proposed a beam steering equation for the planar slotted waveguide array antenna. The tilt angle measured from the rotating axis and the aperture distribution of the antenna were the most important factors for the beam steering. From the equation, we calculated the frequency and phase distribution of the aperture for any desired beam direction. And we developed a high speed control algorithm delivering the phase data to the phase shifters of a one-dimensional phased array antenna. To reduce complexity of the control circuit and the phase delivery time, we proposed the serial phase repeating method. Because of its simplicity, we expect it can be useful for a large 2- dimensional fully phased array antenna.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.4
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• pp.25-33
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• 1999

Leaky wave radiation and surface wave launching problems in a dielectrically covered and periodically slitted parallel-plate waveguide(PPW) are considered for the TEM wave incidence case. Both the infinite and finite periodic geometries are analyzed by use of the method of moments. Some numerical results for the reflected and transmitted powers in the PPW, radiation efficiency into the free space, surface wave launching efficiency into the slab, antenna gain, and radiation patterns against dielectric thickness are presented to show the effect of the dielectric cover on the performances of the slitted leaky wave antenna. In addition, the method for improving surface wave launching efficiency using the proposed periodic geometry is described and maximum launching efficiency of 97.5% is obtained theoretically. So this structure is thought to be promising as an efficient feeder of dielectric grating antenna as well as image guide.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.1
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• pp.73-82
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• 1997

This paper discusses the design and implementation of parabola, lens, and $32{\times}8$ rectangular microstrip patch array antennas at 77GHz for vehicular radar applications. The parabola size was $7{\times}10$ cm and the f/D was 0.263. Open waveguide(WR-12) was utilized as the feed antenna. Two types of lens antennas with f/D=0.5 were investigated ; one was a plano-convex and the other was a double-convex. A patch array antenna was designed using a transmission line model and experimented. Comparing the theoretical values with the measured ones for four antennas, the results were agreed well in 3 dB BW and radiation patterns, while the gain of the patch array antenna was degraded as much as -25 dB due to the feed network and microstrip-to-coax-to-waveguide transition losses.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.4
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• pp.539-544
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• 2017

In this paper, the broadband patch antenna for human counting systems is designed and fabricated using by the air dielectric substrate. Proposed antenna has a patch structure of the square structure with a 5 mm air layer and the vertical connection between the patch antenna and CPW feeding line is realized the stepped impedance structure. Optimized antenna through a 3D EM simulator is fabricated on a jig by manufacturing an antenna jig using a 3D printer with a size of 16.6 * 16.6 * 5 mm3. Proposed antenna is measured with the maximum gain of 5.71 dBi and the VSWR of below 2:1 at a frequency of 7.2 to 9.8 GHz. Also, a half power beam width characteristic of the antenna is measured $70^{\circ}$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.19-25
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• 2015

In this paper, a design method for a CPW-fed slot antenna for harmonic suppression is studied. The structure of the proposed slot antenna is a rectangular slot antenna appended with stepped impedance resonators (SIRs) at both ends of the slot symmetrically. Optimal design parameters are obtained by analyzing the effects of the length and width of the SIRs on the input reflection coefficient. The optimized harmonic-suppressed slot antenna operating at 2.45 GHz WLAN band is fabricated on an FR4 substrate with a dimension of 42 mm by 30 mm. The slot length of the proposed harmonic-suppressed slot antenna is reduced to 33.3% compared to that of a conventional rectangular slot antenna owing to the appended SIRs. Experiment results show that the antenna has a desired impedance characteristic with a frequency band of 2.39-2.49 GHz for a VSWR < 2, and a measured gain of 2.5 dBi at 2.45 GHz.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.2
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• pp.92-100
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• 2002

The 16-port feed waveguide array with inductive walls analyzed by Galerkin's method of moments are proposed for the DBS reception system mounted on vehicle. First of all, in order to verify the validity of electromagnetic analysis and design for a $\pi$-junction feed waveguide, it is designed and fabricated at DBS band. The measurement results of a $\pi$-junction feed waveguide agree well with the theoretical ones. Based on this design method, an array design for WR-90 standard waveguide is conducted. Since the width of a $\pi$-junction feed WR-90 standard waveguide is larger than a guided wave length in an array design, the difference of amplitude and phase of 8-port array are calculated 2.3 dB and 62 degrees, respectively. The bandwidth with return loss of -20 dB below is about 220 MHz and it doesn't satisfy DBS band. To solve this problem, we propose a novel design that the width of a $\pi$-junction feed waveguide equals to a guided wave length. By the proposed novel design for 8-port feed waveguide array, the difference of amplitude and phase are decreased 1 dB and 13 degrees, respectively. The broad bandwidth of 700 MHz is also realized. The size of 16-port waveguide away compared with WR-90 array is reduced about 10 cm. The measured antenna gain for the fabricated 16-port feed waveguide array is observed 24 dBi above at DBS band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.7 s.98
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• pp.732-739
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• 2005

In this paper, the design and implementation of the Ka-band(20/30 GHz) waveguide diplexer with an E-plane T-junction are described. The waveguide diplexer consists of a transmit filter and a receive filter combined to the antenna port via an E-plane T-junction. The reason why the E-plane T-junction structure was selected is to reduce PIM(Passive Intermodulation) level as the split-plane is located in the low electrical current zone. The optimization was performed using the equivalent circuit so that the computation time might reduce. The structure of the diplexer was designed to handle high power and the multipaction analysis was performed. The multipaction margin was greater than 12 dB and satisfied with ESA/ESTEC recommendation. The manufactured diplexer shows minimum return loss of 22 dB, maximum insertion loss of 0.20 dB and maximum isolation of -40 dB for both transmitted receive bands. Those mean the analysis results of the waveguide diplexer were well agreed with the electrical performance test.