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Wideband Circularly Polarized Cavity-Backed Asymmetric Crossed Bowtie Dipole Antenna
Huy Hung Tran,Ikmo Park IEEE 2016 IEEE antennas and wireless propagation letters Vol.15 No.-
<P>A single-feed, cavity-backed, circularly polarized (CP) antenna is designed for wideband wireless applications. The antenna is made up of asymmetric crossed bowtie dipoles and achieves broadband characteristics in terms of impedance and 3-dB axial-ratio (AR) bandwidths. A double vacant-quarter printed ring with orthogonal asymmetric bowties is employed for CP radiation and then combined with slot-mode radiation to significantly enhance the CP operation bandwidth. Measurements of an optimized antenna prototype with an overall size of 0.88A lambda(0), x 0.88 lambda(0) x 0.23 lambda(0),, at 2.4 GHz show that it can yield an impedance bandwidth of approximately 57% and a 3-dB AR bandwidth of approximately 51%. In addition, a unidirectional CP radiation pattern with a high broadside average gain of 9.6 dBic was achieved across the operating bandwidth.</P>
A Dual-Wideband Circularly Polarized Antenna Using an Artificial Magnetic Conductor
Huy Hung Tran,Ikmo Park IEEE 2016 IEEE antennas and wireless propagation letters Vol.15 No.-
<P>A dual-wideband circularly polarized (CP) antenna was proposed based on the strategy of combining multimode resonances. The primary radiators were two barbed-shape dipoles and two bowtie dipoles printed on the same substrate. They were placed over an artificial magnetic conductor (AMC) for the low-profile antenna design purpose. Properly combining the fundamental mode of the barbed-shape dipole, the bowtie mode, the slot mode, the second mode of a barbed-shape dipole, and extra resonance generated by the AMC surface, a dual-wideband operation can be achieved. The final design with an overall size of 0.6 lambda(o) x 0.64 lambda(o) x 0.16 lambda(o) at 2.4 GHz had measured impedance bandwidth of 40% (2-3 GHz) and 49.5% (3.8-6.3 GHz) for the lower and upper bands, respectively. The measured 3-dB axial-ratio bandwidths were 19.3% (2.25-2.73 GHz) and 33.8% (4.3-6.05 GHz) for the lower and upper bands, respectively. The antenna performed an average gain of about 6.6 dBic across the low CP region and 7.4 dBic across the high CP region.</P>
Tran, Huy Hung,Park, Ikmo,Nguyen, Truong Khang IEEE 2017 IEEE antennas and wireless propagation letters Vol.16 No.-
<P>A method of using a simple single parasitic element to significantly enhance a 3-dB axial-ratio (AR) bandwidth of a crossed dipole antenna is presented. This approach is verified by introducing one bowtie-shaped parasitic element between two arms of crossed bowtie dipoles to generate additional resonance and thereby significantly broadening AR bandwidth. The final design, with an overall size of 0.79 <I>λ<SUB>o</SUB></I> × 0.79 <I> λ<SUB>o</SUB></I> × 0.27 <I>λ<SUB>o</SUB></I> (<I>λ<SUB>o</SUB></I> is the free-space wavelength of circular polarized center frequency), resulted in very large measured –10-dB impedance and 3-dB AR bandwidths ranging from 1.9 to 3.9 GHz (∼68.9%) and from 2.05 to 3.75 GHz (∼58.6%), respectively. In addition, the antenna also yielded a right-hand circular polarization with stable far-field radiation patterns and an average broadside gain of approximately 8.2 dBic.</P>
Compact wideband circularly polarised resonant cavity antenna using a single dielectric superstrate
Hung Tran, Huy,Park, Ikmo IET 2016 IET microwaves, antennas & propagation Vol.10 No.7
<P>A wideband resonant cavity antenna (RCA) with circular polarisation (CP) and high-gain characteristics is presented. A crossed bowtie dipole is used as a primary wideband CP radiator for the RCA. A half-wavelength planar partially reflecting surface is utilised to achieve high-gain broadside radiation and wide axial ratio (AR) as well as gain bandwidths. The final design yields measured -10 dB impedance and 3 dB AR bandwidths ranging from 5.6 to 8.4 GHz and from 6.3 to 8.15 GHz, respectively. Experimental results also showed an average gain of 14.5 dBic over the CP operating bandwidth and a 3 dB gain bandwidth of 42.7% (5.7-8.8 GHz).</P>
A Compact Circularly Polarized Crossed-Dipole Antenna for an RFID Tag
Huy Hung Tran,Son Xuat Ta,Ikmo Park IEEE 2015 IEEE antennas and wireless propagation letters Vol.14 No.-
<P>A compact circularly polarized (CP) crossed-dipole antenna for radio frequency identification in the ultra-high frequency is proposed. The antenna consists of two orthogonal dipoles with an arm composed of a meander line and triangular-shaped ending for achieving a compact size. A modified T-match with a meander line is used for impedance matching between the antenna and the tag chip. In this design, CP excitation is achieved by incorporating two semi-circular curves inserted between the orthogonally arranged dipole arms. The final design, with the dimensions of 35.6 ×35.6 ×0.508 mm<SUP>3</SUP>, yields a -10-dB impedance bandwidth of 37 MHz (892-929 MHz) and a 3-dB axial-ratio bandwidth of 11.4 MHz (905.2-916.6 MHz). The measured results show that the proposed tag antenna can provide a maximum reading distance of approximately 7.6 m with an effective isotropic radiated power of 3.28 W over the CP operational bandwidth.</P>
Huy Hung Nguyen,Minh Thien Tran,Dae Hwan Kim(김대환),Hak Kyeong Kim(김학경),Sang Bong Kim(김상봉) 제어로봇시스템학회 2018 제어·로봇·시스템학회 논문지 Vol.24 No.2
This paper proposes a fault detection algorithm for a velocity controller using MRAC in the belt conveyor system of a fish processing line. In general terms, the fault detection algorithm utilizes an extended Kalman filter (EKF) based on a known mathematical model to estimate the state vector and compare computed residue values with a threshold value to determine fault condition. However, a system that models a belt conveyor system has some uncertain parameters. Thus, a fault detection algorithm based on the mathematical model with uncertain parameters can give false alarms or miss detection events. The following can be done to solve this issue: First, a velocity controller based on an MRAC has been designed to estimate uncertain parameters in the belt conveyor system and control belt conveyor velocity to track a reference input asymptotically. Second, an angular velocity output and a friction coefficient are chosen as the state vector and observation vector elements for the EKF. Third, process and observation vector functions are determined and the EKF is used to compute the residue value, which is then compared to a given threshold value to detect a fault. Finally, the simulation and experimental results are shown to verify the proposed algorithm’s effectiveness.
Ikmo Park,Huy Hung Tran,Son Xuat Ta 한국전자파학회JEES 2014 Journal of Electromagnetic Engineering and Science Vol.14 No.3
A wideband circularly polarized (CP) antenna with a single feed is proposed for use in global navigation satellite systems. Its primary radiation elements are composed of two orthogonal bowtie dipoles, which are equipped with double-printed vacant-quarter rings to allow direct matching of the antenna to a single 50-Ω coaxial line and to produce CP radiation. The crossed bowtie dipole is appropriately incorporated with a planar metallic reflector to produce the desired unidirectional radiation pattern as well as to achieve a wideband characteristic in terms of impedance matching and axial ratio (AR) bandwidths. The designed antenna was fabricated and measured. The prototype antenna with an overall 1.2-GHz frequency size of 0.48 λo×0.48 λo×0.25 λo produced a measured |S11|<-10 dB bandwidth of 1.05-1.79 GHz and a measured 3-dB AR bandwidth of 1.12-1.64 GHz. It also showed right-hand CP radiation with a small gain variation (±0.3 dB) and high radiation efficiency (>93%) over the operational bandwidth.