• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1176-1179
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• 2011

In this paper, design of series-fed microstrip antennas with sum and difference patterns is presented for millimeter-wave applications. The antenna was designed to exhibit high-gain and low side-lobe level(SLL) below -20 dB. A conventional transmission-line model, Taylor and Bayliss distributions were employed to determine current distribution for sum and difference patterns. Moreover, connecting lines between microstrip patches were tuned to achieve an optimized design. The measurement was also performed to validate the designed antennas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.3
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• pp.379-387
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• 2000

In this paper, to transmit and receive the differently polarized wideband signals simultaneously with a single antenna system, the wideband, dual-frequency and dual-polarized(WDFDP) microstrip array antenna is proposed and designed. This antenna operates simultaneously at 14.25 GHz and 12.50 GHz. To extend to two dimensional array, microstrip feed line and coaxial probe through via-hole are used. The experimental results show that the proposed WDFDP microstrip antenna can be used in the compact portable terminals with a single antenna system and the characteristic of the resonators in this antenna produces a greatly enhanced bandwidth.

• Journal of the Korean Society for Railway
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• v.17 no.3
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• pp.171-177
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• 2014

PWM converter trains exhibit excellent load characteristics in comparison with conventional phase-controlled trains with low power factors, as they can be operated at power factors which are close to unity by means of a voltage vector control method. However, in the case of a high track density or extended feeding, significant line losses and voltage drops can occur. Instead of operating these trains at a fixed unity power factor, this paper suggests a continuous optimal power factor control scheme for each train in an effort to minimize line losses and improve voltage drops according to varying load conditions. The proposed method utilizes the steepest descent algorithm targeting each car in the same feeding section to establish the optimized reactive power compensation levels that can minimize the reactive power loss of the feeder. The results from a simulation of a sample system show that voltage drops can be improved and line losses decreased.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.9
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• pp.13-19
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• 1998

It was shown that the bandwidth of T-shaped microstripline fed slot antenna is wider than many of the conventional feeding structures. In this paper, we proposed a new method of enhancing the bandwidth of T-shaped microstripline fed slot antenna with a shunt open stub, and analyzed this antenna by using the FDTD method. We have computed waves and electric field distribution in the time domain, and VSWR, input impedance and radiation pattern in the frequency domaim by Fourier transforming the time domain results. It was found that the bandwidth of this antenna depend on the position(L$_1$) and length(L$_2$) of a shunt open stub. When these parameters are L$_1$=30 mm and L$_2$=33mm, we obtained the maximum bandwidth at the center frequency of 2.3 GHz. From the computed results, the optimum antenna is designed and fabricated. The fractional bandwidth of this antenna was 53.9 %. The measured results were in relatively good accordance with computed values.

• Journal of the Korea Society of Computer and Information
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• v.18 no.3
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• pp.27-34
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• 2013

A wideband patch antenna fed by an L-strip feeder is studied. The objective of this paper is to design small wideband antenna for 3G and 4G wireless mobile communication service. The enhanced features were confirmed and proved by comparing the proposed antenna with the antennae that have been reported in the relevant literatures. Measurement results confirm that an impedance bandwidth($VSWR{\leq}2$) of 636MHz(32.5%, fo=1,960MHz) is achieved at 3G and 4G frequency band for L-strip-fed triangular patch antenna. In general, probe feed has only the parasitic reactance caused by the probe, which reduces the bandwidth performance of the antenna. The experimental results proved that the effects of improvement could be achieved because the proposed antenna is capable of compensating the parasitic reactance from the feeding mechanism. The studied antenna can be designed easily for extension of array because it has simple structure.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.795-801
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• 2001

A method of miniaturizing branch line coupler is presented. The method utilizes the microstrip line with overlay(or superstrate). The frequency dependent characteristics, dispersion and characteristic impedance, of this line are obtained by Immitance method in spectral domain and Method of Line. The relevant spectral domain Green's function is given and used to obtain numerical results. The branch line couplers with overlays are designed and fabricated at 2 GHz. The experimental results show that the size of coupler with overlay(${epsilon}_r$=10.2) is 31.4 precent smaller than conventional coupler. This minimized coupler is suitable for Butler Matrix as feeder for mobile communication beam forming antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.3
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• pp.425-431
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• 2001

In this paper, on aperture-coupled microstrip cylindrical dielectric resonant antenna(DRA) consisting of dielectric material with permittivity ${\epsilon}_{r}$ = 36 is designed and fabricated fir wireless LAN. First of all, the feedline length, width, slot length and width of the feeding element were calculated using the theory of microstrip transmission line. Radiation element is designed using the theory of cylindrical dielectric cavity, Resonant frequency of the fabricated cylindrical DRA is 2.449 GHz and VSWR, return loss and bandwidth is 1.009, -47 dB and 70 MHz, respectively. Front-to-back radiation ratio is about 12 dB and 3 dB beamwidth of E-plane and H-plane is 110$^{\circ}$ and 90$^{\circ}$ , respectively.

• Advanced Industrial SCIence
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• v.3 no.2
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• pp.31-37
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• 2024

This paper presents a single and 2-patch microstrip array antenna operated on a frequency of 10.3GHz(x-band). It outlines the process of designing a microstrip patch array antenna using CST MWS. Initially, a single microstrip antenna was designed, followed by optimization using CST MWS to attain optimal return losses and gain. Subsequently, the design was expanded to create a 2×1 microstrip inset-fed array antenna for the X-band applications. The construction material is Roger RO4350B, with specific dimensions (h=0.79mm, 𝜖_r = 3.54). The achieved results include an S11 of -18dB at the resonant frequency (10.3GHz), a gain of 9.82dBi, a bandwidth of 0.165GHz, and a 3-dB beamwidth of 30°, 121° in Az(𝜑=0) and El(𝜑=90) plane, respectively. The future plan involves the fabrication of this array antenna and further expansion to a 4×4 array of microstrip antennas. It is then incorporated on the X-band applications for practical uses.

• Journal of Satellite, Information and Communications
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• v.10 no.2
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• pp.80-85
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• 2015

In this paper, we present, an indstrial RFID layered microstrip patch antenna is designed using an inset feed method in order to improve recognition rates in a long distance as tags are attached to metal object by improving a problem of feeding power in fabricating metal tags and reducing effects of metallic object. The inset feed shows a distinctive characteristic that has no separation between emitters and feed lines differing from a structure with the conventional inductive coupling feed. This structure makes possible to produce a type that presents a low antenna height and enables impedance coupling for tag chips. Although it shows a difficulty in the impedance coupling due to increases in the parasite capacitance between a ground plane and an emitter in an antenna according to decreases in the height of a tag antenna, it may become a merit in designing the tag antenna because the antenna impedance can be determined as an inductive manner if a shorted structure is used for feeding power. Therefore, in this paper the microstrip patch antenna is designed as a modified type and applies the inset feed in order to reduce effects of metallic objects where the antenna is be attached. Also, the antenna uses a multi-layer structure that includes a metal plate between radiator and ground instead of using a single layer.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.5
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• pp.413-420
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• 2009

We propose a novel feed network for a $2{\times}2$ array antenna to form a sectoral conical beam. The proposed feed network, which is a symmetrical structure, consists of four $90^{\circ}$ hybrids, a crossover, and four $90^{\circ}$ delay lines. To verify the performance of the feed network a $2{\times}2$ array antenna and the feed network are fabricated on a microstrip structure, and the radiation patterns are measured at the center frequency of 2.57 GHz. The maximum radiation is measured at the $45^{\circ}$ elevation angle and at the $45^{\circ}$, $135^{\circ}$, $225^{\circ}$, and $315^{\circ}$ azimuth angles depending on the choice of the input port of the feed network.