Hong-Kyun Ryu

A Compact Ultrawideband MIMO Antenna With WLAN Band-Rejected Operation for Mobile Devices

This letter presents an ultrawideband multiple-input-multiple-output (MIMO) antenna that covers the WCDMA (1.92-2.17 GHz), WiMAX (2.3, 2.5 GHz), WLAN (2.4 GHz), and UWB (3.1-10.6 GHz) bands for wireless device applications. The proposed antenna consists of a printed folded monopole antenna coupled with a parasitic inverted-L element, with an open stub inserted in the antenna to reject the WLAN (5.15-5.85 GHz) band that interferes with the UWB band. These two antennas are symmetrically arranged on a mobile device substrate. The -10-dB bandwidth of the designed antenna is 1.85-11.9 GHz without the WLAN band 5.15-5.85 GHz. S21 and the envelope correlation coefficient are lower than -17.2 dB and 0.18 in the operating bands, respectively. The size of the antenna is 55 ×13.5 × mm2.

Compact Multiband Microstrip Antenna Using Inverted-L- and T-Shaped Parasitic Elements

By placing inverted-L- and T-shaped parasitic elements at both the radiating apertures of a microstrip patch antenna, a low-profile, compact single-layer multiband microstrip antenna operable in various bands has been developed. These bands include LTE TDD No. 34 (2.0175 GHz), WLAN (2.45 GHz), and WiMAX (3.5 GHz) bands. The antenna has dimensions of 0.26 λ_L ×0.25 λ_L ×0.03 λ_L, where λ_L is the free-space wavelength at 2.0175 GHz, and resonance in the parasitic elements occurs through coupling and perturbations to the microstrip patch. In each band, the measured -10-dB bandwidths cover the required bandwidths at 28 MHz (1.39%), 91 MHz (3.71%), and 255 MHz (7.29%). Within each of the designed bands, a broadside radiation pattern is observed.

An Electrically Small Spherical UHF RFID Tag Antenna With Quasi-Isotropic Patterns for Wireless Sensor Networks

An electrically small spherical UHF (911.25 MHz) radio frequency identification (RFID) tag antenna is proposed. A dipole-typed RFID tag antenna is wound into a spherical shape to achieve small size and quasi-isotropic pattern. The overall diameter of the antenna is 25 mm (0.076¿), and the resulting electrical size is a kr of 0.24. A short stub is employed for good conjugate impedance matching with a RFID chip (Zchip = 14 - j145 ¿). The designed antenna has a -10-dB bandwidth of 7 MHz (0.77%) and the maximum readable distance of 132 cm at 5.2 W EIRP.

Size Reduction in UHF Band RFID Tag Antenna Based on Circular Loop Antenna

In this paper, small-sized RFID tag antenna is designed and fabricated based on the circular loop antenna used in UHF band (860-960 MHz). The tag antenna with its center frequency at 911.25 MHz (wave length lambda: 329 mm) adopts a parallel transmission line feed method to match the impedance and reduces its size using a stub. As a result, the antenna (diameter lambda: 54 mm) with 15 stubs reduces its size up to 69.6% compared with the one without any stub. The measured return loss is -9.942 dB, -3 dB bandwidth is 84.35 MHz(9.26%) and the gain in z-x plane is -0.37 dBd. The radiation pattern shows a magnetic dipole antenna characteristic and omnidirectional pattern in horizontal plane

Small-sized square loop antenna using meander line for RFID tag applications

In this paper, a small-sized square loop antenna (SLA) for a RFID tag antenna is designed and fabricated at the UHF band. As the structure of a meander line in a general SLA is applied, the SLA is miniaturized. The small meander line SLA is reduced to 85.4% compared with a general SLA. The radiation patterns shows omnidirectional in z-y plane (horizontal pol.). Also the gain of the meander line SLA is -2.47dBd. Through these results, we can confirm that miniaturized type SLA using meander lines are suitable for miniaturized RFID tag antennas with the UHF band. We apply the small-sized SLA to the RFID chip.

Miniaturization of log-periodic dipole array antenna using triangular meander structure

This paper has been designed the miniaturized LPDA antenna applying the triangular meander structure. To reduce the basic LPDA antenna, four dipole elements for low frequency band of the basic LPDA antenna were changed into triangular meander structure except for the other elements to keep the performance of high frequency band. The proposed antenna was miniaturized up to 60 % compared with the basic LPDA antenna. The average gain was measured as 6.69 dBi.

Helmet installed antenna using a half-wavelength circular loop antenna

Recently, in a field of a construction work, the use of wireless communication network is increased for easy communication among workers. They use mostly radio handsets when using wireless communication network. At this time, safety and work efficiency could be not good by holding them with a one-hand. A radio handset within a helmet is effective in order to reduce this dangerous situation. If one of the important components which are antenna for a helmet with a radio handset is disclosed, it has damage according to the environment. Therefore, the antenna has to be inside of a helmet and easy to attach on it with a flat shape. Also a good communication condition has to be maintained by a proper position. Attaching a miniaturized planar antenna on the underside of a visor is proposed. It is a half wavelength circular loop antenna (CLA) with a voluntary frequency at 449MHz. And it is manufactured by printed type for mass production. The diameter, 200mm, has to be miniaturized for attaching it on a visor. Therefore, the antenna is miniaturized with a double meander line inside of a loop. And then characteristics of installing on a visor and human body are studied. We would like to explain the characteristics of the designed antennas.

Ultrawideband Planar Dipole Antenna With a Modified Taegeuk Structure

This letter presents an ultrawideband (UWB) planar dipole antenna. The initial design of the proposed antenna is patterned after the “taegeuk” structure, which has two curves and a 180° rotational symmetry structure. To achieve UWB impedance matching, the curve of the structure was modified into a tapered curve, and the feed gap was controlled. The measured -10-dB S₁₁ bandwidth was more than 50:1 (over 0.2-10 GHz). The antenna size was 450 mm ( 0.3λ_L) × 540 mm ( 0.36λ_L), where λ_L is the free-space wavelength at 0.2 GHz. The length of the designed antenna was miniaturized by 22.8% compared to that of a half-wave dipole antenna at 0.2 GHz.

A Printed, Wideband Folded Monopole Antenna Coupling with a Parasitic Inverted-L Element for Bluetooth, WiMAX and UWB Systems

This paper presents a printed, wideband folded monopole antenna for laptop and tablet computer applications. The proposed antenna is designed to cover bandwidth(2.3~10.6 GHz) of Bluetooth, WiMAX, and UWB system by using the printed folded monopole antenna having asymmetrical line width coupling with a parasitic inverted- L element. Also, wireless LAN band(5.15~5.85 GHz) which interferes with UWB system is rejected by inserting half-wavelength open stub in the folded monopole antenna. -10 dB bandwidth of the fabricated wideband antenna is 2.27~10.6 GHz (4.7:1) and -10 dB band-rejected bandwidth is measured as 700 MHz(5.15~5.85 GHz, 12.72 %). The gain and efficiency of the antenna except for the rejected band are higher than 3.93 dBi and 91.89 % and are measured as -2 dBi and 14.65 % at 5.5 GHz which is band-rejected frequency. The size of the antenna is suitable to install for small space of tablet and laptop computers as 12.75(1 /10)12(1 /11) ( is free space wavelength at 2.3 GHz). Therefore, we verified that the designed antenna is appropriate for wideband antenna of tablet and laptop PC applications.

A small quarter wavelength microstrip antenna for HF and VHF band applications

This paper presents a small quarter wavelength microstrip antenna for HF and VHF band applications. The designed antenna is based on a quarter wavelength microstrip antenna whose the patch size is the same as the ground plane. The antenna is miniaturized by inserting four zigzag plates at the end of the microtrip antenna. The size of the miniaturized antenna is 60 × 60 × 30 cm3 which is correspondent with electrical sizes kr of 0.61. The size reduction rate is 76.5%. The two omnidirectional radiation patterns are observed in the zy plane Eθ and the xy plane Eθ.