• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.5
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• pp.38-43
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• 2015

In this paper, we present novel dual-band microstrip antennas using inverted-L-shaped parasitic elements vertically at radiation apertures for GPS L1(1.575 GHz) and L2(1.227 GHz) bands. For making dual band which has large interval, the inverted-L-shaped parasitic element was loaded at the radiation aperture of a half-wavelength patch antenna(GPS L1) in opposite direction of the feeding point for receiving the low frequency(GPS L2). The low frequency occurs by perturbation and coupling between the patch and parasitic. Next, due to use circular polarizations at the GPS applications, two inverted-L-shaped parasitic elements were loaded at radiation apertures of each polarizations and the feeding point was moved at diagonal part of the patch. The dimensions of the designed circularly polarized antenna were $88.5{\times}79{\times}10.4mm^3$ ($0.36{\lambda}L{\times}0.32{\lambda}L{\times}0.04{\lambda}L$, ${\lambda}L$ is the free-space wavelength at 1.227 GHz). Measured -10 dB bandwidths were 116.3 MHz(7.4%) and 64.3 MHz(5.2%) at GPS L1 and L2 bands, respectively. All of these cover the respective required system bandwidths. The measured 3 dB axial ratio bandwidths were 11.7 MHz(0.74%) and 14 MHz(1.14%), respectively. Within each of the designed bands, broadside radiation patterns were observed.

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.503-507
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• 2007

In this paper, the ultra-widebend, microstrip patch antenna with the bandwidth of 3 GHz was implemented for ultra-wideband(UWB) wireless communication applications. In order to cover the very wide bandwidth of 3 GHz, a multi-resonance antenna was designed, each resonance frequency was separated into five frequency bend, 7.5, 8.1, 8.7, 9.3, and 9.9GHz with the interval of 600MHz BW. And for wideband characteristics of each antenna, U-slot antennas were designed at each center frequency. Designed five U-slot antennas were connected in series for multi-resonance of 3GHz BW and wideband matching was also designed for impedance matching transmission line calculated. The relative dielectric constant, the height, the loss tangent of the PCB substrate were ${\epsilon}_r=4.8,\;h=0.6$ and loss tangent=0.0009 respectively. The implemented antenna's radiation patterns and gain were directivity characteristics and $1.46{\sim}4.08dBi$ at the five separated center frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.5 s.96
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• pp.526-533
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• 2005

In this paper, the miniaturized the linear polarization and the circular polarization microstrip antennas, which are the two ends in the resonance length direction or all the four-ends were folded are designed and fabricated at the resonant frequency of 1.575 GHz(fur GPS system). For the linear polarization microstrip antenna, the antenna was bent. downward so that the visible length(=L) was reduced by $31.7\%(\varepsilon_r=1.06)$. The folded antenna was folded toward the center of the antenna once again. In this case, the visible length reduction rate, gain, -10 dB bandwidth, E-plane and H-plane HPBW were $73.9\%$, 5.12 dBd, $64MHz(4\%),\;151^{\circ}\;and\;79.2^{\circ}$, respectively. For the circular polarization microstrip antenna, the folded structure of the linear polarization antenna was applied to all the few directions. For the most efficiency the folded bottom surfaces were designed in a triangular shape. In this case, the visible area reduction rate, gain, -10 dB bandwidth, and HPBW in horizontal polarization of the z-x plane and the z-y plane were $71.5\%,\;3.96dBd,\;84MHz(5.3\%),\;80.6^{\circ}\;and\;82.1^{\circ}$, respectively. Therefore, we have confirmed that the folded structure is suitable fer the miniaturization of the microstrip antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.8
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• pp.886-892
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• 2010

In this paper, the hybrid antenna utilizing epsilon negative zeroth-order resonance(ENG ZOR) and $TM_{010}$-mode is presented. The antenna has a directional radiation pattern and improved bandwidth. To obtain a ENG ZOR and $TM_{010}$-mode, the hybrid antenna employs the mushroom structure and the microstrip patch, respectively. Two antennas of the mushroom and the patch are coupled by gap and fed by one coaxial feed. The frequencies of ENG ZOR and of $TM_{010}$ resonance are designed to be 4 GHz and 3.9 GHz, respectively. Because two resonant frequencies are set to be close, the dual-resonance can be formed, resulting in the broader bandwidth. Even though the radiation pattern of an ENG ZOR antenna is omnidirectional, the directional radiation of a microstrip patch antenna compensates the null of omnidirectional pattern of an ENG ZOR antenna. Thus, the hybrid antenna has a directional radiation pattern. The antennas having 4, 3, and 2 unit cells of mushroom structure are designed and analyzed. The antennas have fractional bandwidths of 4.29~4.95 %, gains of 3.16~5.57 dBi, and radiation efficiencies of 62.4~94.2 %.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.489-495
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• 2018

In this paper, we designed and fabricated WLAN / UWB communication antennas operating at 3.3 [GHz] and 5 [GHz] bands in order to effectively use the high-speed communication network system that improved antenna miniaturization, gain and radiation pattern. Microstrip patch antennas were chosen to improve the bandwidth. The slot width, length, and transmission line width were calculated using the theoretical formula for each step. Simulation results show that the return loss is -14.053 [dB] at 3.3 [GHz] and -13.118 [dB] at 5 [GHz]. The gain showed a value of 2.479 [dBi] at 3.3 [GHz] and a value of 3.317 [dBi] at 5 [GHz]. After optimizing it with the CST Microwave Studio 2014 program, which can be 3D-designed, Based on these results, we investigated the performance of antennas by measuring their characteristics. In recent years, WLAN, which is a variety of wireless technologies that are continuously developing, and UWB, which is a communication technology which is increasing in frequency band due to an increase in demand of the technology users, is used for a high speed wireless communication system. Communication seems to be possible.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3205-3214
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• 1996

In this paper, the microstrip phased array antennas with coupling-slots for the base station of mobile communication is proposed and anlyzed with accurate analysis method which is based on both reciprocity principle and full-wave analysis. The basis functions used for the numerical analysis are determined depending upon the accuracy, convergence properties of the solution, and the computation time. The patch uses 3 EB mode and the slot uses IPWS mode. The designed phased array antenna has 8 slot-coupled microstrip patch array elements and the beam scanning capability is obtained by using the 4-bit PIN-diode phase shifters as switching devices which are consisted of the loaded line phase shifters for 30.deg. and 60.deg. and the reflection type phase shifters for 90.deg. and 180.deg. repectively. The 4-bits phase shifters which aremade by connecting each phase shifter have about 2.deg.-3.deg. phase errors and their insertion loss are about 3dB for each phase state. The fabricated 8-element phased array antenna with 4-bits phase shifters provides 12.deg.-14.deg. beamwidths depending on the scanning angle and is capable of scanning its beam to .+-.45.deg. with 9.deg. intervals, and the gain 12dBi. The overall results show that the slot-coupled phased array antenna has great advantages of wideband, high gain and reduced spurious radiation. Also, the antenna can be made small and thin. Furthermore, the scanning property of this antenna allows for its application in several areas, such as mobile communication system and PCS.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1248-1258
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• 2010

In this paper, a method for simultaneously realizing the sum and difference patterns which are required in the monopulse radar sensor systems, is presented by using single taper array antenna with rectangular microstrip patches. The widths of patches are first determined by the voltage weights which are synthesized for the fundamental array factor patterns to be applied to the monopulse operation by using the sidelobe levels(SLLs) control technique. As the bi-directionally series-fed technique is applied and the lengths of connecting lines between patches are appropriately adjusted, the single array generates two phase-shifted beams which activates out-of-phase and in-phase ports of a $180^{\circ}$ hybrid coupler to synthesize the sum and difference patterns. The simulated results on the configuration designed at 9.5 GHz are compared with measured results showing the validity of the proposed method.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.4
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• pp.73-79
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• 2015

Enhanced bandwidths of the GPS microstrip patch antennas applied by a Wilkinson power divider and a quadrature hybrid were compared. The square patch was designed, and fed by the two port probes for the circuit application. The Wilkinson power divider and quadrature hybrid circuit were designed, and applied to the patch antenna. The designed patch and two circuits were implemented on the FR4 board, and combined together. The measurement of the bandwidth within a voltage standing wave ratio (VSWR) of 2: 1 were 36.5% (1,200~1,775 MHz) in the case of the Wilkinson power divider and 29.84% (1,230~1,700 MHz) in the case of the quadrature hybrid. Axial ratios (AR) in 3dB were 17.14% bandwidth (1,360~1,630 MHz) and 15.87% bandwidth (1,400~1,650 MHz), respectively. The application of the Wilkinson power divider is wider than that of the quadrature hybrid. The peak gains in the anechoic chamber at the GPS center frequency were measured as 2.84 dBi and 2.75 dBi, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.813-823
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• 1998

This paper analyzed the circularly polarized conformal microstrip patch antennal using the unsplit anisotropic perfectly matched layer(UAPML) method. Also, this paper are treated effectively the edge and corner parts on the 3 dimensional UAPML. Especially, to analyze microstrip patch antennas with the coaxial feeder line, it was applied to mixed the UAPML with Mur's first order absorbing boundary condition. Therefore this paper suggest the new the method to mix the UAPML with Mur's first order absorbing boundary condition. The results show the time responses of electromagnetics $E_z$ and $H\chi'$, input impedances of coaxial cable and radiation patterns of strip parchs on the single and the array patchs with central frequencies 1.575 GHz, 1.778 GHz and 4.8 GHz in L-band and C-band for mobile communication. The results of this paper shows that its results was compared the Mur's first order abc and mixed the second order dispersion boundary condition(SDBC) with the Mur's first order absorbing boundary condition. In accordance with, the validity of the method is confirmed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.6
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• pp.920-928
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• 2000

In this paper, using newly proposed size reduction technique, the aperture coupled microstrip patch antenna for a repeater system in a mobile communication cellular band (824~849 MHz) is developed with a wide bandwidth, small size, light weight, and low cost. The resonant frequency of microstrip antennas is related to the electric field distribution of the radiating patch. The field strength of $TM_{01}$ mode of a rectangular patch antenna is strongest at each of the extremities of the radiating patch, but negligible at center. Therefore, the size of a patch antenna can be effectively minimized by inserting the narrow rectangular dielectric into just under the edges of the resonant Patch. This Paper also proposes the bandwidth improvement technique by using under-coupling technique with a tuning stub. The VSWR is less than 1.5 : 1 for the whole cellular band. The simulation tool was HFSS, Agilent Technologies, Inc.