Dong Hyuk Choi

Bio: Dong Hyuk Choi is an academic researcher from Samsung. The author has contributed to research in topics: Bistatic radar & Dipole antenna. The author has an hindex of 2, co-authored 2 publications receiving 436 citations. Previous affiliations of Dong Hyuk Choi include Information and Communications University.

A miniature UWB planar monopole antenna with 5-GHz band-rejection filter and the time-domain characteristics

Abstract: A planar monopole antenna with a staircase shape and small volume (25times26times1 mm3) is proposed in this paper. With the use of a half-bowtie radiating element, the staircase-shape, and a modified ground plane structure, the proposed antenna has a very wide impedance bandwidth measured at about 11.6 GHz (2.9-14.5 GHz, bandwidth ratio about 1:5) below VSWR 2 including the WLAN band notched in the vicinity of 5 GHz. An omnidirectional radiation pattern is obtained. The group delay which is an indication of linearity between two proposed antennas is less than 1 ns. The electrical characteristics in terms of frequency and time domains and physical ones of the proposed antenna make it attractive for use in ultrawideband (UWB) systems

Noninvasive Biosignal Detection Radar System Using Circular Polarization

Abstract: This paper proposes an integrated hypersensitive Doppler radar system through a circular polarization characteristic. Through the idea of a reverse sense of rotation when the reflecting surface is perfectly conducting, it is shown that the detecting property of the system can be effectively improved by using antennas that have a reverse polarization. This bistatic radar system can be used in noninvasively sensing biosignals such as respiration and heart rates with the periodic movement of skin and muscle near the heart. The operating frequency of the system is in the X-band and the radar size is 95 times 50 times 13 mm3.

A Compact Ultrawideband Antenna With 3.4/5.5 GHz Dual Band-Notched Characteristics

Abstract: We propose a compact planar ultrawideband (UWB) antenna with 3.4/5.5 GHz dual band-notched characteristics. The antenna consists of a beveled rectangular metal patch and a 50 Omega coplanar waveguide (CPW) transmission line. By etching two nested C-shaped slots in the patch, band-rejected filtering properties in the WiMAX/WLAN bands are achieved. The proposed antenna is successfully simulated, designed, and measured showing broadband matched impedance, stable radiation patterns and constant gain. An equivalent circuit model of the proposed antenna is presented to discuss the mechanism of the dual band-notched UWB antenna. A UWB antenna and a single band-notched one are also provided for references.

Compact Printed UWB Diversity Slot Antenna With 5.5-GHz Band-Notched Characteristics

Abstract: A novel compact printed ultrawideband (UWB) slot antenna for MIMO/diversity applications is presented in this letter. The antenna consists of two modified coplanar waveguides (CPWs) feeding staircase-shaped radiating elements for orthogonal radiation patterns, where a rectangle stub is placed at 45° between the CPW to ensure high isolations. By etching two split-ring resonator (SRR) slots on the radiators respectively, the band-notched property is achieved. Results show that this antenna meets a 10-dB impedance bandwidth and 15 dB isolation from 2.5 to 12 GHz, with a notched band at 5.5 GHz. The measurements of the radiation patterns and envelope correlation coefficient (ECC) denote that the antenna is suitable for multiple-input-multiple-output (MIMO)/diversity systems. Furthermore, it has a compact size of 48 × 48 mm2, which has been significantly reduced, and it is a good candidate for portable devices.

UWB Elliptical Monopoles With a Reconfigurable Band Notch Using MEMS Switches Actuated Without Bias Lines

Abstract: Two CPW-fed elliptical monopoles were fabricated on liquid crystal polymer (LCP) with reconfigurable rejection band (band-notch) characteristics in the frequency range between 5 and 6 GHz. The first antenna uses a lambda/2 long, U-shaped slot and the second antenna uses two symmetrically placed lambda/4 long, inverted L-shaped stubs as resonating elements. Microelectromechanical system (MEMS) switches are used to activate and deactivate the resonating elements without the need of dc bias lines due to a novel design of the switch geometry. Transmission line models and surface current distributions are used to explain the effect of the added resonating elements. Reflection coefficient radiation pattern and gain measurements are presented to verify the design concepts featuring a very satisfactory performance.

A Band-Notched Ultrawideband Printed Monopole Antenna

Abstract: In this letter, a band-notched ultrawideband (UWB) antenna is presented and the notched-band characteristic is realized by a compact coplanar waveguide (CPW) resonant cell (CCRC). The antenna with a total size of 46 mm $,times,$30 mm operates in a band from 2.67 to over 12 GHz, and shows omnidirectional radiation patterns. Measurements indicate that the antenna presents a notched band from 5.10 to 5.94 GHz for $ VSWR ge 3:1$, which covers the wireless local area network (WLAN) band. The time-domain behaviors and the CCRC are discussed and the group delay is given experimentally. Also, parametric studies are performed numerically in the end.