• ETRI Journal
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• v.31 no.1
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• pp.71-73
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• 2009

In this letter, novel antennas with two spiral elements are presented for ultra-wideband application. The original antenna consists of a T-shaped microstrip feed line, two spiral radiating elements, and a ground plane with two circular slots. It measures 30 mm ${\times}$ 40 mm ${\times}$ 1.6 mm. Spiral elements are used to increase the lower bandwidth limit. To further reduce the size of the antenna, the original antenna is cut in half by using the symmetry of the surface current distributions. The proposed antennas feature omnidirectional radiation patterns and good gain flatness.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.2325-2331
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• 2012

Planar square-spiral antenna using a strip conductor is proposed and analyzed for RFID system in UHF band operating from 860MHz to 960MHz. By varying the length of common line, detached distance, strip line-space, strip line-width and the number of spiral turn, the optimized antenna are designed and fabricated in compact size without a matching-stub between the input port of the proposed antenna and RFID tag chip. From the optimized results, the frequency bandwidth in VSWR<2 has covered 100MHz in the RFID UHF band. The antenna gain has obtained 3.5dBi at the center frequency of 910MHz and the desired beam pattern has shown directional pattern on elevation and azimuth angle. Therefore, the proposed antenna is suitable for practical RFID applications requiring various tag chips with the specific input impedance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.5
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• pp.468-474
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• 2002

In this paper a novel two-arm microstrip spiral antenna with a circular slot on the ground plane is presented. The proposed antenna structure is constructed in a planar form without a balun circuit and the radiation characteristics of conventional and eccentric spiral antennas are obtained simultaneously. The main beam direction is normal to the plane of the spiral for characteristic frequency band and the direction of the main beam moves linearly into $\theta$ and $\phi$ direction as the frequency increases.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.12
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• pp.1370-1382
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• 2007

In this paper, the spiral planar monopole antenna mounted on a Cellular/WCDMA handset is designed. Frequency characteristics is optimized with various design parameters. The two spiral lines are adopted in order to implement Cellular frequency bandwidth and WCDMA frequency bandwidth. The bandwidth of the realized antenna is $0.805{\sim}0.892$ GHz(10 %) and $1.867{\sim}2.302$ GHz(21 %) for VSWR${\leq}2$ which contain the proposed frequency bandwidth. In human head, the simulated value on 1 g and 10 g averaged SAR caused by electromagnetic wave radiated in the designed antenna is compared with the measured value. As a result, the measured values of 1 g and 10 g averaged SAR were similar to the simulated values, which were lower than the SAR guidelines.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.2
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• pp.135-140
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• 2008

In this paper, the spiral antenna with the center frequencies of 315MHz, 433MHz, and 447MHz for RKE system of a vehicle is designed on PCB. The antenna is microstrip line-fed, and applied PIFA concept near the feeding part to easily tune center frequency and input impedance. The PIFA-type spiral antenna with the size of $30mm{\times}20mm$ is designed on printed PCB by considering the effect of circuits and components on PCB, ECU case and vehicle body. Also chip inductor inserted dual-band spiral antenna of 315MHz and 447MHz is designed. We found that the antenna designed on PCB satisfied the antenna specifications through measurement and field test.

• Journal of IKEEE
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• v.23 no.3
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• pp.762-767
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• 2019

The plane-wave shielding effectiveness is typically measured for horizontal and vertical polarizations using a linearly polarized antenna. However, this typical measurement method results in big evaluation fees due to very long measurement time as well as huge idle space for maintenance, these problems is more severe especially in large shielded enclosures such as EMP protection facilities to be built in indoor buildings and underground. This paper describes the design and fabrication process and results of a planar log-spiral antenna applicable to the evaluation of the electromagnetic shielding effectiveness of a large EMP protection facility. Since the proposed antenna has a circular polarization, there is no need to separately measure the horizontal and vertical polarizations. Therefore, the measurement time can be shortened by more than 1/2, and further, its small volume with a planar structure can reduce greatly idle space required for the maintenance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.208-214
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• 2009

A design and its experimental result of a wideband self-complementary spiral antenna for UWB USPR(Ultrashort-Pulse Radar) system applications is presented. By utilizing the planar-type ultra-wideband microstrip-to-CPS balun, ultra-wideband characteristics of the inherent spiral antenna are retrieved. Also, the design procedure of the spiral antenna is simplified by performing simple impedance matching between separately designed balun and antenna. The proposed spiral antenna is equiangular self-complementary spiral antenna. The implemented antenna demonstrates widebaad performance for frequency ranges from 2.9 to 12 GHz with the relatively flat antenna gain of 2.7 to 5.3 dB and broad beamwidth of more than $70^{\circ}$. From these result, the possibility of a spiral antenna using a ultra-wideband microstrip-CPS balun is verified.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.6 s.97
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• pp.563-570
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• 2005

In this paper, a small-sized planar square-spiral monopole antenna is proposed by using parasitic elements. The Parasitic element is composed of a crossed strip and additional right-angle folded(L-type) stirps. And these parasitic elements are printed on a substrate which is the opposite side of a radiation element . When the parasitic elements are used, the size of the square-spiral monopole antenna is reduced by $32\%$ for the same operating frequency compared to the antenna without parasitic elements. The radiation pattern of the proposed antenna is nearly omni-directional in azimuth. The designed antenna can be used in the application of channel 12 digital mulimedia broadcasting(DMB) handset.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.753-760
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• 2009

In this paper, a novel planar spiral antenna of multi-tabs is proposed for wireless power transmission system based on low frequency magnetic inductive coupling. The proposed antenna has higher transmission efficiency than conventional antennas such a rectangular spiral antenna and a spiral antenna. Also, it has a useful property of uniform power transmission in the region of the antenna aperture. For verification, a transmitting antenna and a receiving one for a wireless power transmission system using magnetic inductive coupling of 132 kHz low frequency are designed and tested. The transmitting antenna has three-tabs spiral of unequal-space for higher uniform magnetic coupling in the antenna aperture. For reducing the receiving antenna size, two receiving antennas of unequal space two-tabs on one-side and series double sides as well are designed, respectively. From measurement, transmission efficiency of the proposed antennas is improved up to $3{\sim}10$ dB compared to conventional antennas.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.5
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• pp.16-22
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• 2001

A novel microstrip circular slot antenna fed by a spiral line is presented in this paper. This antenna is a planar equivalent structure of an eccentric spiral antenna generates a circularly-polarized wave. We have investigated the input impedance and radiation characteristics of this antenna by using an EM (electromagnetic) simulator, and obtained a design method [or optimum structure. The main characteristic of the antenna is that the main beam direction is off-normal to the antenna plane and moves linearly into ${\theta }$ and ${\phi }$ direction as the frequency increases. This feature allows one to predict the main beam direction easily for a given operating frequency. This antenna has axial ratio lower than 3 dB in the direction of main beam over one octave bandwidth.