• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.2 s.117
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• pp.111-117
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• 2007

In this paper, a new marchand balun using broadside-coupled coplanar waveguide(CPW) on flexible printed circuit (FPC) is proposed. The proposed balun is designed based on the coupled line theory. The fabricated balun shows compact size and improved performance compared to the conventional microstrip line marchand balun. Measured amplitude and phase imbalance between the two balanced output ports are within 0.2 dB and $1^{\circ}$ respectively in a wide frequency range($1.63{\sim}3.44$ GHz). The proposed balun is expected to be used between various antennas and RF front-ends as a functional interconnection.

• ETRI Journal
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• v.32 no.1
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• pp.112-119
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• 2010

We present a useful design for a free access mat which supports two frequency bands of 2.4 GHz and 5 GHz. The free access mat is a sheet-shaped waveguide which consists of a tightly coupled double-layered microstrip resonator array. It provides easy access for devices in short-range wireless communications. Interference is a common problem with conventional applications which use free space transmission. Our proposed wireless access system uses a subsidiary waveguide, the free access mat. Wireless devices are proximately coupled to the free access mat through which the coupled electromagnetic (EM) wave transmits. The arrival domain of the EM wave of an application is therefore limited to an area close to the free access mat. Wireless devices can be coupled to the free access mat at an arbitrary position without contact. We previously presented a free access mat for a single frequency band. This paper presents a free access mat for the two frequency bands of 2.4 GHz and 5 GHz. The free access mat uses a ring patch resonator array which is easily excited by typical antennas and is resistant to interference. These characteristics are demonstrated by numerical simulation and confirmed by experiment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1604-1611
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• 2003

For dual­band operation, it can be done by loading two pair of slits in the equilateral­triangular patch, one embeded close to the side edges of the patch and the other inserted at the bottom edge of the patch. The frequency ratio of the two operating frequencies can be tuned by varing the positions and lengths of the inserted slots at the bottom edge of the patch. While the calculated frequency ratio of the antenna by Ensemble 5.0 is $1.66 ({f_10}=1.928GHz, {f_20}=3.2GHz)$, the measured one is 2.04 $({f_10}=1.6806 GHz, {f_20}=3.435 GHz)$. The error in the frequency ratio is due on the fabrication dimension and feeding position error as well as on the permittivity dispersion effect.

• Journal of Satellite, Information and Communications
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• v.12 no.2
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• pp.83-88
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• 2017

In this paper, we propose a three-element CRPA array with improved low-elevation gain. The proposed antenna consists of a feed patch and a radiating patch, and the feed patch is connected by a coaxial cable. The radiating patch is electromagnetically coupled to the feed patch, which allows to improve the low-elevation gain of the antenna. To demonstrate the suitability of the proposed antenna, the antenna characteristics are measured in a full anechoic chamber. The resulting bore-sight gain is 2.8 dBic with an axial ratio of 2.7 dB, and the average gain at the low-elevation direction of $75^{\circ}$ is -1.4 dBic. The results verify that the proposed antenna is suitable for CRPA arrays with anti-jamming capability.

• Journal of the Semiconductor & Display Technology
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• v.17 no.2
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• pp.20-25
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• 2018

In this paper, we have designed circularly polarized array antenna for 5.8GHz microwave wireless power transmission. To obtain high antenna gain, we studied a single patch antenna, a $2{\times}1$ array antenna, a $2{\times}2$ array antenna, a $2{\times}4$ array antenna, and a $4{\times}4$ array antenna. Commonly, characteristics of each antenna have a frequency of 5.8 GHz and Right Hand Circular Polarization(RHCP) of circular polarization. Also, the results were obtained with the design to each antenna that the return loss was less than -10dB and the axial ratio was less than 3dB. The gain of the antennas was 6.08dBi for a single patch antenna, 9.69dBi for a $2{\times}1$ array antenna, 12.99dBi for a $2{\times}2$ array antenna, 15.72dBi for a $2{\times}4$ array antenna and 18.39dBi for a $4{\times}4$ array antenna. When the elements of the array antenna were increased, it was confirmed that it increased by about 3dBi.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.2
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• pp.192-201
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• 2003

In this paper, to reduce the size of patch, three types of 3-dimensional patch antennas which are one-directionally-corrugaged type, rectangular ring-likely corrugated type, and lattice-likely corrugated type rectangular microstrip patch antennas(MPA) are designed and fabricated at the 1.575 GHz. As the result, one-directionally corrugated rectangular MPA is reduced in the resonant length of patch by 21.4% than that of general plane MPA. -10 dB bandwidth(B.W) is 62 MHz(3.9 %) and this is broader than that(39 MHz, 2.5 %) of plane MPA by 23 MHz(1.5 %). The gain is 5.8 dBd and this is reduced by 0.9 dB than that(6.7 dBd) of plane MPA. Half power beamwidth(HPBW) is broadened by 18$^{\circ}$ than that of plane MPA in the E-plane and this is due to the reduced length of patch. For rectangular ring-likely corrugated retangular MPA, the patch size is miniaturized by 21.6 % than that of plane MPA. For lattice-likely corrugated rectangular MPA, in the linear polarization, the size of patch is miniaturized by 43.3 % than that of plane MPA. -10 dB B.W is 70 MHz(4.4 %) and this is broadened than that of plane MPA by 31 MHz(2 %). Gain is 2.2 dBd and this is smaller than that of plane MPA by 4.5 dB. HPBW is increased in both E-plane and H-plane by 22$^{\circ}$ and 13$^{\circ}$, respectively. For circular polarization, the size of patch is reduced by 41 % than that by 41 %. The axial ratio(AR) is 0.8 dB at the 1.575 GHz and the axial ratio bandwidth(ARBW) within 2 dB is 20 MHz(1.27 %) and this is increased by 10 MHz(0.63 %) than that 10 MHz(0.63 %) of plane MPA. From all the results above, it is conformed that the proposed antenna has merit in size reduction of patch and in the input impedance B.W, and is more profitable in many application than the general plane type MPA.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.442-448
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• 2018

In this paper, a microstrip antenna for LTE / LTE-A is designed and fabricated for a broadband mobile communication system. The proposed antenna is designed to have the characteristics of using FR-4 (er = 4.3), size of $40mm{\times}50mm$, and LTE / LTE-A frequency bands of 2.3 GHz and 2.5 GHz. 2014, and the simulation result shows that the gain is 2.391 dBi at 2.3 GHz and 2.566 dBi at 2.5 GHz. The S-parameter also showed a result of less than -10 dB (WSWR 2: 1) in the desired frequency band. The broadband mobile communication antenna has been miniaturized, high performance, and light weight, and an excellent and low cost system is continuously being developed, and a broadband mobile communication system is used by many people. Since LTE / LTE-A technology has been proposed according to the development of system and demand, it is expected that many users will design and manufacture antennas satisfying the above conditions and apply the applied technology.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.449-455
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• 2018

For the size reduction, we propose a microstrip-fed monopole antenna with half X-slot in the radiation patch and cover WLAN dual band 2.4 GHz band (2.4 ~ 2.484 GHz) and 5 GHz band (5.15 ~ 5.825 GHz). The frequency characteristics such as impedance bandwidth and resonant frequencies were satisfied by optimizing the numerical values of various parameters, while the reflection loss in 5 GHz was improved by using defected ground structure (DGS). The proposed antenna is designed and fabricated on a FR-4 substrate with dielectric constant 4.3, thickness of 1.6 mm, and size of $24{\times}41mm^2$. The measured impedance bandwidths (${\mid}S_{11}{\mid}{\leq}-10dB$) of fabricated antenna are 450 MHz (2.27 ~ 2.72 GHz) in 2.4 GHz band and 1340 MHz (4.79 ~ 6.13 GHz) in 5 GHz band which sufficiently satisfied with the IEEE 802. 11n standard in dual band. In particular, radiation patterns which are stable as well as relatively omni-direction could be obtained, and the gain of antennas in each band was 1.31 and 1.98 dBi respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.522-525
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• 2018

In this paper, we design a UWB / WAS microstrip antenna for wireless local high - speed communication. The substrate of the proposed antenna is FR-4 (er = 4.3) and its size is $30[mm]{\times}30[mm]$. It is designed to have characteristics that can be used in the frequency bands of 3.5 [GHz] and 5.2 [GHz], which are UWB / WAS frequency bands. The simulation was performed using CST Microwave Studio 2014. Simulation results show that the gain is 1.592 [dBi] at 3.5 [GHz] and 2.210 [dBi] at 5.2 [GHz]. The S-parameter also showed a result of less than -10 [dB] (WSWR 2: 1) in the desired frequency band. Microstrip antennas have been miniaturized, high performance, and light weight, and excellent and low cost systems are continuously being developed. In addition, many people use wireless local area network systems used in homes, companies, and public facilities. Since the UWB / WAS technology is proposed according to the development of the system and the demand increase, the antenna that satisfies the above conditions will be designed and the technology applicable to the system will be used more conveniently.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.2
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• pp.157-167
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• 2003

In this paper, to reduce the resonant length of patch, microstrip patch antenna of linear polarization which is suppressed at two radiation edges is designed and fabricated at the frequency of 1.575 GHz. The result is like that the resonant length of patch is 45 mm and the length reduction effect is 43.8 % when it is compared with that(80 mm) of plane type. The gain is 4.4 dBd and -3 dB beamwidths are 112$^{\circ}$ and 66$^{\circ}$ in the E-plane and H-plane, respectively. Also, to reduce the size of patch, microstrip patch antennas those are suppressed at four radiating comers are designed and fabricated at the same frequency in the linear and circular polarization, respectively. For linear polarization, at the 1.2 of width/length(W/L) ratio, the patch area is 53 mm $\times$ 63.6 mm and the size reduction effect is 56.1 % when compared with that(80 mm $\times$ 96 mm) of plane type. The gain is 4.3 dBd and the -3 dB beamwidths are 120$^{\circ}$ and 78$^{\circ}$ in the E-plane and H-plane, respectively. For circular polarization, the patch size(54.2 mm $\times$ 61.5 mm) is reduced by 47.2 % than that(76 mm $\times$ 83 mm) of plane type. -3 dB beamwidth of horizontal polarization in the z-x plane and vortical polarization in the y-z plane are 108$^{\circ}$ and 93$^{\circ}$, respectively and this means the increasement in both planes by 52$^{\circ}$ and 27$^{\circ}$ than those of plane type. The maximum gain is 2.5 dBd in the horizontal polarization in the z-x plane. Axial ratio is 1.5 dB at 1.575 GHz and the 2 dB axial ratio bandwidth(ARBW) is 20 MHz(1.3 %).