• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.979-983
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• 2008

Planar antennas are very efficient for the use of the out-door data transmission applications due to their low-profile characteristics. But the size of the antenna in UHF band blocks the practical usage. In this paper, a miniaturized planar antenna is investigated for the application of AMR system in UHF band. The designed antenna is fabricated in the form of the microstrip patch on the FR-4 substrate. The miniaturization is achieved by slot-loading on the patch. First, effects of simple slots on the size reduction are analyzed, followed by the design using more complex slots resulting in the reduction ratio of 37.9% in 425.6 MHz and bandwidth of 3.8 MHz. The effort of epoxy coating for the protection is also investigated.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.293-296
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• 2005

This paper presents the design of linear and circular polarization baseball- shaped circular microstrip antenna (BCMA) with 3-dimensional structure using perturbation effect to reduce its size, which runs at 1.575GHz frequency bandwidth. As a result, the size of linear polarized antenna could be reduced up to 23.7% in patch diameter and 41.8% in its area. Linear polarized antenna has -26.04dB of return loss, 69MHz(4.38%) of -l0dB bandwidth, 4.51dBd of gain, and its -3dB beamwidth are 99$^{\circ}$ in E-plane, 83$^{\circ}$ in H-plane. Circular polarized antenna has -17.43dB of return loss, 113.7MHz(7.2%) of -l0dB bandwidth, 2dBd of gain, 2dB of axial ratio and its -3dB beamwidth are 87$^{\circ}$, 86$^{\circ}$ x-axis polarized, 80$^{\circ}$, 84$^{\circ}$ y-axis polarized. It has 82mm of diameter, which is 28.5% of linear polarized CMPA. Therefore, in this paper we verified that baseball-shaped 3-dimensional structure of circular microstrip patch antenna applied with perturbation effect is appropriate for miniaturization.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.3
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• pp.321-328
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• 2008

In this paper, a novel log-periodic cantor dipole antenna(LPCDA), which is composed of the cantor-dipole elements instead of the existing dipole elements, is proposed. The proposed antenna makes possible the antenna miniaturization by using the cantor-dipole elements. To investigate the reliability of the proposed antenna, LPCDA is designed and analyzed at $1{\sim}4GHz$ band and compared with LPDA(Log-Periodic Dipole Antenna) characteristics. It is shown that although the elements of LPCDA are 13.3% shorter than LPDA, the gain increases about 2dB and VSWR is less than 2 in at the upper band.

• Journal of electromagnetic engineering and science
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• v.17 no.2
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• pp.108-110
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• 2017

The global positioning system (GPS) is a useful system in civilian and military applications. However, because of the weak signal, GPS receivers are vulnerable to interference caused by unwanted signals or intentional jammers. To alleviate this issue, a controlled reception pattern antenna (CRPA) array can be employed to adaptively place radiation pattern nulls toward the direction of the signal interference. The performance of the CRPA array improves as the number of antenna elements increases. Therefore, antenna miniaturization is highly desirable for CRPA applications. We designed a compact CRPA array based on seven electrically miniaturized microstrip patch antennas (MPAs) on a 5-inch ground platform. We used a non-Foster matching circuit to match efficiently miniaturized MPAs on an FR-4 substrate. Experimental results show that the non-Foster matching circuit significantly improves such elements of antenna performance as return loss and antenna gain. In addition, we confirmed that the mutual coupling of the proposed CRPA array is less than -45 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.6 s.121
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• pp.591-601
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• 2007

In this paper, the miniaturized radio frequency identification(RFID) tag antennas used in UHF band$(908.5{\sim}914MHz)$ are designed and fabricated by using the circular loop antenna(CLA). Miniaturization of CLA was possible to transform the structure of circular loop into the structure of meander line. In the case of double meander line CLA is reduced up to 83% compared with the general type CLA. The $S_{11}$, -10 dB bandwidth, and gain of double meander line CLA were -11.9 dB, 12 MHz(1.3%), and -1.18 dBd. Also, a small half-wavelength CLA using double meander line is designed and fabricated for flat snack bag coated aluminum. The antenna is reduced up to 92.1% except ground. It shows the $S_{11}$ of -16.5 dB, -10 dB bandwidth of 48 MHz(5%) and gain of -0.58 dBd. The radiation pattern shows omni-directional pattern in z-y plane(x-axis pol.). Through this result, we can confirm that miniaturized type CLAs using meander lines are suitable for miniaturized RFIB tag antennas with the UHF band.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.2045-2049
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• 2018

An antenna arrays for a satellite navigation systems require more antenna elements to mitigate multiple jamming signals. In order to maintain the small array size while increasing the number of antenna elements, miniaturization technique is essential for antenna design. In this work, an electrically small circular microstrip patch antenna with a 3 dB hybrid coupler is designed as an element antenna, where the 3 dB hybrid coupler can yield the circularly polarized radiation characteristic. The miniaturized element antenna typically has too large capacitance in GPS L1 and GLONASS G1 bands, making it difficult to match with a single stand-alone non-Foster matching circuit (NFMC) in a stable state. Therefore, we propose a new matching technique, referred to as the hybrid matching method, which consists of a NFMC and a passive circuit. This passive tuning circuit manages reactance of antenna elements at an appropriate capacitance without a pole in the operating frequency range. The antenna array is fabricated, and the measured results show a reflection coefficient of less than -10 dB and an isolation of greater than 50 dB. In addition, peak gain of the proposed antenna is increased by 22.3 dB compared to the antenna without the hybrid matching network.

• ETRI Journal
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• v.35 no.3
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• pp.530-533
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• 2013

In this letter, a simple method for reducing the size of a dual-band planar inverted-F antenna (PIFA) is described. This method is based on a coupling capacitor connected in parallel to the PIFA feed conductor. The proposed antenna occupies a small ground clearance of $10mm{\times}5mm$ and is able to provide -10-dB impedance bandwidths of 120 MHz and 760 MHz for 2.45-GHz and 5.5-GHz wireless local area network applications, respectively. The measured antenna efficiencies are 71.8% and 73.6%, averaged over the 2.45-GHz and 5.5-GHz frequency bands, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.51-52
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• 2013

In this paper, circularly polarized microstrip for the S-band with a center frequency of 3.5GHz have been studied using the meta-structure of the resonator Designed antenna using CST studio, the meta-structure resonator was etched in the ground plane for miniaturization and circulary polarization was implemented with slot in center of the patch.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.1091-1094
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• 2005

This paper presents analysis and design for printed directive antenna using Bluetooth AP system. For the miniaturization of the antennas, dielectric substrate (${\varepsilon}_r$=4.6) and planar line Yagi-Uda antenna structure are used. The proposed Yagj-Uda antennas are simulated using commercial simulator (HFSS). The results of the simulation are presented and compared with characteristics of each array type. Especially, the proposed antennas can be applied to the design of various communication systems for 2.4 GHz band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.9
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• pp.777-782
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• 2015

In this paper, the compact CPW-fed antenna with triple folded patch for dual-band WLAN applications is proposed. As the conventional double inverted-L antenna is changed into the C-shaped patch and double inverted-L antenna, the antenna overcomes the narrow-band characteristics according to the miniaturization of the antenna. The proposed antenna with the size of only $16.5mm{\times}29.5mm{\times}1.0mm$ is designed and fabricated by optimized parameters to be operated at 2.4 GHz band and 5 GHz band. The antenna is fabricated into FR-4 substrate with thickness of 1.0 mm. We confirm that it is operated as antenna for WLAN applications by obtaining the measured return loss level of < -10 dB at dual-band.