Ikmo Park

Ikmo Park
Ajou University · Department of Electrical and Computer Engineering

Doctor of Philosophy

About

187
Publications
92,056
Reads
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3,225
Citations
Additional affiliations
September 1987 - January 1994
University of Illinois, Urbana-Champaign
Position
  • Research Assistant

Publications

Publications (187)
Article
Full-text available
The design and performance of low-profile, multiple-feed metasurface antennas with different numbers of patch cells and different substrate thicknesses at a terahertz frequency are presented in this paper. The utilized antenna designs consist of a periodic array (N × M) metallic square-patch metasurface and a planar feeding structure, which are bot...
Conference Paper
Full-text available
This paper presents the design of a planar, low-profile, high-gain, wide-gain-bandwidth metasurface antenna with a multiple feeding structure. The antenna structure consists of a 5×5 array of square patch metasurface and a planar feeding structure, both of which are patterned on a high-permittivity, electrically thin, GaAs substrate. The metasurfac...
Article
We designed various photoconductive antennas applicable to efficient terahertz (THz) receivers and experimentally investigated their detection characteristics. Three different antennas based on Grischkowsky (H-), I-, and bowtie shapes were fabricated on a 1.2-μm-thick low-temperature GaAs layer that was grown on a semi-insulating GaAs substrate and...
Conference Paper
Full-text available
A planar, low-profile wide-gain-bandwidth metasurface antenna at terahertz frequency is presented in this paper. The proposed antenna consists of a metasurface and a planar feeding structure, both of which are patterned on a thin, high permittivity substrate. The metasurface, printed on the top side of the substrate consists of a periodic array of...
Article
Full-text available
Two compact planar crossed-dipole antennas loaded with near-field resonant parasitic (NFRP) elements are reported. The NFRP and crossed-dipole elements are designed for the desired CP radiation. By placing the NFRP element over the driven element at angles of 0° and 45°, respectively, dual-band and broadband CP antennas are realized. All radiating...
Conference Paper
Full-text available
In this paper, we optimized the small lens for a slit dipole antenna to behave as a leaky-wave antenna. An extended hemispherical silicon lens was attached at the back side of a slit dipole antenna and the antenna gain and radiation pattern characteristics were investigated over a frequency range from 200 to 400 GHz. The numerical results show that...
Article
Full-text available
We designed a slit dipole antenna backed by an extended hemispherical silicon lens and investigated the minimum lens size in which the slit dipole antenna works as a leaky-wave antenna. The slit dipole antenna consists of a planar feeding structure, which is a center-fed and open-ended slot line. A slit dipole antenna backed by an extended hemisphe...
Conference Paper
This paper presents a wideband circularly polarized (CP) beam-steering antenna with the capability of generating several steerable beams. A single radiator is first constructed with two triangular-shaped dipoles, and four parasitic elements for wide CP operation bandwidth. The array antenna is implemented in a 2 × 2 arrangement and fed by a four-in...
Article
Full-text available
This paper presents a planar circularly polarized (CP) antenna array with a high-gain and wideband operation. The array is based on a sequentially rotated feeding network for a set of 2 × 2 CP metasurface-based antennas. The single element is a microstrip-line-fed slot antenna, which is coupled to a metasurface having 4 × 4 truncated corner square...
Article
Full-text available
A compact wideband resonant cavity antenna is presented. A single layer of an approximately half-effective-wavelength-thick partially reflecting surface, which has a very wide transmission band and the positive slope of a reflection phase against frequency, is employed to achieve very wide half power gain bandwidth. The experiment results demonstra...
Article
Full-text available
A cavity-backed angled-dipole antenna is proposed for millimeter-wave wireless applications. The angled-dipole radiator is built on both sides of an RT/Duroid 5880 substrate ( ε r = 2.2 ) and fed by a parallel-plate transmission line. The cavity-backed reflector is utilized to improve the radiation characteristics of the angled dipole, such as...
Article
Full-text available
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 bandw...
Conference Paper
Full-text available
In this paper, we investigate and compare the radiation characteristics of a planar substrate-integrated Fabry-Perot cavity antenna designed with different unit-cell geometries. The antenna consists of a frequency selective surface (FSS) and a planar feeding structure, which are both lithographically patterned on a high-permittivity substrate. The...
Article
Full-text available
A wideband circularly polarized (CP) antenna with an artificial magnetic conductor (AMC) reflector is presented. Its primary radiation elements are composed of two bowtie dipoles which are arranged orthogonally through double-printed rings to allow easy impedance matching and produce good CP radiation. Planar periodic square metallic plates, which...
Conference Paper
Full-text available
Department of Electrical and Computer Engineering, Ajou University, Suwon, Republic of Korea A cavity-backed angled-dipole antenna is proposed for low millimeter-wave band wireless applications. A cavity-backed reflector was utilized to improve the radiation characteristics of the angled dipole, such as gain, back-radiation, and 3-dB beamwidths in...
Article
Full-text available
This paper presents dual-band operation of a single-feed composite cavity-backed four-arm curl antenna. Dual-band operation is achieved with the presence of the asymmetrical arm structure. A pair of vacant-quarter printed rings is used in the feed structure to produce a good circular polarization (CP) at both bands. The cavity-backed reflector is e...
Article
Full-text available
A circularly polarized (CP) switched-beam antenna array with the capability of generating nine steerable beams in the hemispherical space is presented in this letter. A single radiator is first constructed with two triangular-shaped dipoles crossing through printed rings, and four parasitic elements are introduced to enhance the CP operation bandwi...
Article
Full-text available
This letter presents a compact wideband sequential-phase (SP) feed for use in sequentially rotated antenna arrays. The SP network is designed to match a 50-Ω coaxial line. The phase difference (out-of-phase) between the outer and inner conductors of the coaxial line is utilized as a 180° phase shifter; consequently, the desired phases at the output...
Article
Full-text available
A low-profile single-feed circularly polarized (CP) patch antenna using metasurface is proposed for broadband operation. The antenna is comprised of a truncated corner square patch sandwiched between a lattice of 4 × 4 periodic metal plates and the ground plane. Surface waves propagating on the metasurface are excited in the proposed structure. Thi...
Article
Full-text available
Crossed dipole antennas have been widely developed for current and future wireless communication systems. They can generate isotropic, omnidirectional, dual-polarized (DP), and circularly polarized (CP) radiation. Moreover, by incorporating a variety of primary radiation elements, they are suitable for single-band, multiband, and wideband operation...
Article
Full-text available
This paper presents the design of a planar, low-profile, high-gain, substrate-integrated Fabry-Pérot cavity antenna for K -band applications. The antenna consists of a frequency selective surface (FSS) and a planar feeding structure, which are both lithographically patterned on a high-permittivity substrate. The FSS is made of a circular hole array...
Article
This paper presents an optimum design of a substrate-integrated cavity-type antenna for use in the terahertz frequency range. The antenna was designed with a frequency-selective surface (FSS) and a planar feeding structure that are both patterned on a high-permittivity gallium-arsenide substrate. The FSS, printed on the bottom side of the substrate...
Conference Paper
In this paper, we propose a planar and highly directive cavity type of antenna in the terahertz frequency range. The antenna consists of a frequency selective surface (FSS) and an open-ended narrow slotline dipole, which are both lithographically patterned on a high-permittivity gallium-arsenide substrate. The FSS in conjunction with the ground pla...
Conference Paper
Full-text available
This paper presents a single-feed dual-band circularly polarized composite cavity-backed four-arm curl antenna. A pair of vacant-quarter printed rings is utilized in the feeding structure to produce good impedance matching and circular polarization (CP). A cavity-backed reflector is employed to improve the CP radiation characteristics, such as 3-dB...
Conference Paper
A single layer and single feed high gain Fabry-Perot cavity type antenna is presented in this paper. The antenna is designed to operate at around 22 GHz so that it can be used for K-band applications. An open-ended leaky-wave slit dipole fed by a coplanar waveguide is printed on one side of the substrate whereas a frequency selective surface made o...
Research
Korea Patent (10-2013-0073198)
Research
Korea Patent (10-2013-0073198)
Article
Full-text available
A circularly polarized single-feed four-arm curl antenna is presented in this paper. We demonstrate that a four-arm curl antenna can be fed by a single 50-H source without a matching network and can produce good circularly polarized (CP) radiation at the desired frequency. A curl antenna normally exhibits as a resonant antenna and its input impedan...
Conference Paper
We designed a single-feed microstrip antenna in a Fabry-Perot resonator cavity used for Ku-band (12–18 GHz) applications. A cavity was formed by a ground plane and a frequency selective surface made of a circular hole array and was excited by a single-feed microstrip patch located inside the cavity. The antenna with low-profile and reduced thicknes...
Conference Paper
Full-text available
This paper introduces a single-feed dual-band antenna for an anti-jam global positioning system array. The antenna is composed of a circularly polarized (CP) crossed scythe-shaped dipole over a finite artificial magnetic conductor (AMC) reflector. The dual-band operation is obtained by utilizing the original band generated by the radiator and an ad...
Article
Full-text available
This paper presents single-feed circularly polarized (CP) crossed dipole antennas on finite-sized artificial magnetic conductor (AMC) surfaces that show profile miniaturization and bandwidth enhancement. The antennas include a singleband radiator on a single-band AMC, a tri-band radiator on a single-band AMC, and a dual-band radiator on a dual-band...
Article
Full-text available
A circularly polarized (CP) antenna with a wideband characteristic is proposed for use in the Global Navigation Satellite System. Its primary radiation element is crossed bowtie dipoles, which are incorporated with double-printed vacant-quarter rings to allow the antenna to be matched directly to a single 50-Ω coaxial line and produce wideband CP r...
Article
Full-text available
A single-feed dual-band antenna with wide-beam circularly polarized (CP) radiation is introduced for application in the global positioning system (GPS). The primary radiating element is a planar multiarm curl antenna. The dual-band operation is achieved by dividing the arms of the antenna into two branches of different lengths. To generate CP radia...
Article
Full-text available
A crossed dipole that is loaded with a magneto-electric dipole to produce the wideband and wide-beam circularly polarized radiation characteristics is proposed. The crossed dipole is incorporated with double-printed vacant-quarter rings to feed the antenna. The antenna is backed by a metallic cavity to provide a unidirectional radiation pattern wit...
Article
Full-text available
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...
Article
Full-text available
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 empl...
Article
Full-text available
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...
Article
Full-text available
A single-feed composite cavity-backed four-arm curl antenna is presented for use in global positioning systems (GPS). Its primary radiating element is fed by a vacant-quarter printed ring, which helps the antenna directly match to a 50-{\Omega} coaxial line and produce a good circular polarization (CP). The cavity-backed reflector is employed to im...
Conference Paper
In this paper, the influence of a substrate lens made of high-permittivity material on the overall performance of a traveling-wave stripline dipole antenna is presented. Input impedance and radiation characteristics of the antenna are fully investigated over a broad frequency range up to 5.0 THz. The results show that the lens shape represented by...
Article
Full-text available
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-{\Omega} coaxial line and to prod...
Conference Paper
Full-text available
A crossed dipole antenna is incorporated with an AMC surface to achieve low-profile and broadband characteristics. Interactions between the crossed dipole and the AMC surface are meticulously considered for optimum design. The antenna yields an impedance bandwidth of 18.8% for |S11| < -10 dB and a 3-dB AR bandwidth of 10.9%.
Conference Paper
This paper presents the design of a leaky-wave slit antenna incorporated with a frequency selective surface (FSS) in a high-permittivity gallium arsenide (GaAs) substrate for terahertz applications at around 300 GHz. The narrow slit on the top side of the substrate is excited by a delta-gap voltage source at the center and acts as a perfect mirror,...
Article
This paper proposes the design of small CRPA arrays for dual-band Global Positioning System (GPS) applications. The array consists of five elements and is mounted on a circular ground platform with a diameter of 15-cm. Each antenna element has a coupled feed structure and consists of a feed patch and two radiating patches for dual-band operation. A...
Article
In this paper, a study of a stripline dipole antenna on a substrate lens used as a photoconductive detector in a terahertz system is presented. The traveling-wave behavior of the stripline dipole and the influence of the substrate lens are investigated over a broad frequency range up to 5.0 THz. The numerical results show that the lens shape repres...
Article
We propose a bandwidth-enhanced four-leaf-clover-shaped photomixer antenna for use in terahertz wireless communication systems. The antenna was designed with a highly resonant radiation element, a stable DC feed element with photonic bandgap structure, and two symmetrical parasitic elements electromagnetically coupled with the main radiator for ban...
Article
We report on the effect of dielectric substrate on the resonance shift of metallic metamaterials operating in the terahertz frequency region. The resonance frequencies for various metamaterials obtained by time-domain spectroscopy agree well with calculations based on the finite-difference time-domain method. The dependencies of the resonance frequ...
Conference Paper
The input impedance and radiation characteristics of a stripline dipole antenna on different substrate schemes are presented. Two radiation environments, a semi-infinite galliumarsenide substrate (hereafter called a 'semi-infinite substrate') and a thin gallium-arsenide substrate backed by a silicon lens (hereafter a 'lens substrate'), were examine...
Article
Full-text available
An ultra-wideband (UWB) circular monopole antenna with a multiband-notched characteristic is proposed. The multiband-notched filter consists of three different sized folded slots, which are distinctly assigned for the notched band at the 3.5-GHz WiMAX, 5-GHz WLAN, and 8-GHz ITU bands. The proposed antenna results in a measured < -10 dB, which compl...
Conference Paper
Full-text available
Circularly polarized crossed dipole antennas are presented in this paper. A compact crossed dipole is realized with the use of a meander line and a barbed end in each dipole arm. A vacant-quarter printed ring is used as a 90° phase delay line to achieve circularly polarized radiation. For multi-band applications, each dipole arm is divided into mul...
Article
Full-text available
A dual-band, low-profile, circularly polarized antenna on an artificial magnetic conductor (AMC) is introduced in this letter. The antenna employs a single feed and two crossed asymmetric dipoles as the primary radiating elements. In order to achieve a low profile and broadband characteristics in terms of impedance matching and 3-dB axial-ratio (AR...
Article
Full-text available
This paper describes composite cavity-backed crossed scythe-shaped dipoles with wide-beam circularly polarized (CP) radiation for use in Global Navigation Satellite Systems. Each branch of the dipole arm contains a meander line, with the end shaped like a scythe to achieve a significant reduction in the size of the radiator. For dual-band operation...
Article
Full-text available
This communication presents a multi-band, circularly polarized (CP), wide beamwidth, highly efficient antenna for use in global positioning systems (GPS). The primary radiating elements are two crossed printed dipoles, which incorporate a 90° phase delay line realized with a vacant-quarter printed ring to produce the CP radiation and broadband impe...
Conference Paper
Full-text available
In this paper, a wide-beam circularly polarized (CP) composite cavity-backed crossed scythe-shaped dipole is proposed. Each dipole arm contains a meander line whose end is shaped like a scythe chine to accomplish a significant reduction in the radiator size. The scythe-shaped dipoles are crossed through a 90° phase delay line of a vacant-quarter pr...
Article
Full-text available
This paper introduces a high-efficiency, high-gain, broadband quasi-Yagi antenna, and its four-element array for use in 60-GHz wireless communications. The antenna was fed by a microstrip-to-slotline transition consisting of a curved microstripline and a circular slot to allow broadband characteristics. A corrugated ground plane was employed as a r...
Conference Paper
We experimentally investigated the terahertz (THz) photoresponse of vertically-aligned single-walled carbon nanotube (SWCNT) films by using optical pumping method. The SWCNT film was grown on the fused quartz substrate by using the alcohol catalytic CVD process. We observed that the strong THz radiation is emitted from the photoexcited SWCNT film....
Conference Paper
Full-text available
This paper presents a circularly polarized (CP) dual-band crossed dipole antenna incorporated with an artificial magnetic conductor (AMC) surface that serves as a reflector. Here, two crossed asymmetric dipoles are utilized as the primary radiation elements for a CP dual-band operation. Further, a novel AMC is designed with four T-shaped slits in a...
Book
Recent technological breakthrough in the field of Terahertz radiation has triggered new applications in biology and biomedicine. Particularly, biological applications are based on the specific spectroscopic fingerprints of biological matter in this spectral region. Historically with the discovery of new electromagnetic wave spectrum, we have always...
Article
We investigated the dependence of the input impedance and radiation characteristics on the connection angle between the DC bias stripline and the center dipole of a terahertz coplanar stripline dipole antenna in a semi-infinite substrate. Three connection angles, namely 0° (typical horizontal connection), 45° (diagonal connection), and 90° (vertica...
Article
Full-text available
A planar, lightweight, crossed dipole antenna with circularly polarized (CP) radiation is introduced for application in a radiofrequency identification handheld reader at ultrahigh frequency bands. The dipoles cross through a 90 phase-delay line of a vacant- quarter printed ring that enables broadband characteristic in terms of impedance matching...
Article
Full-text available
A novel miniaturized artificial magnetic conductor (AMC) is proposed for dual-band operation. An AMC unit cell that employs four slots in the metallic patch is used to achieve miniaturization as well as easy control of the second/first resonant frequency ratio, which can be varied from 1.5 to 3.26 by simply changing the slot shape for a given metal...
Article
Full-text available
This paper describes a wideband double dipole quasi-Yagi antenna fed by a microstrip-to-slotline transition. The transition feed consists of a microstrip radial stub and a slot radial stub, each with the same angle of but with different radii, to achieve wideband impedance matching. Double dipoles with different lengths are utilized as primary radi...
Article
Full-text available
In this paper, we present a circularly polarized (CP) composite cavity-backed crossed dipole antenna for global positioning system (GPS) applications. We produce the CP radiation by crossing two dipoles through a phase delay line of a vacant-quarter printed ring, which also has a broadband impedance matching characteristic. Two techniques, insertio...
Conference Paper
Full-text available
A dual-band printed dipole antenna with wide-beamwidth radiation patterns is introduced for 2.4/5 GHz bands wireless local area network access points. A printed dipole is designed at the center of circular ground plane and fed by a novel integrated balun consisting of a curved microstrip-line and a circular slot to allow broadband operation. An ang...
Conference Paper
Full-text available
This paper presents a closely spaced two-element folded-dipole-driven quasi-Yagi array with low mutual coupling between adjacent elements. The antenna utilizes a T-junction power divider as the feeding network with an input impedance of 50 Ω. A microstrip stub is added to the ground plane in the middle of the two elements to improve the mutual coup...
Conference Paper
An antenna design to increase the directivity of a terahertz (THz) photomixer used as a THz source is presented. The antenna is consisted of a full-wavelength dipole on a GaAs membrane substrate and covered by a frequency-selective surface (FSS). The perfect mirror of ground plane and the partially reflective mirror of FSS form a resonator which pr...
Article
The aim of this study was to investigate the effects of a 1.8 GHz continuous electromagnetic fields (EMF) on human nasal mucociliary transport, and to determine the pathophysiology of ciliary beat frequency (CBF) during an EMF-induced change. Human nasal mucosa cells were exposed to a 1.8 GHz EMF (SAR=1.0 W/kg), and CBF was analyzed using an optica...
Article
This paper presents the antenna design parameter dependency on the impedance and radiation characteristics of a terahertz coplanar stripline dipole antenna. The antenna response is numerically investigated by applying a semi-infinite substrate and by generating a constant voltage source to drive a signal on the antenna. In this way, we can analyze...
Article
Full-text available
A triband circularly polarized (CP) crossed-dipole antenna is introduced for 2.4/5.2/5.8-GHz wireless local area network (WLAN) applications. It employs a single feed and only two crossed trident-shaped dipoles as the primary radiating elements. To achieve a compact radiator size, two techniques are utilized, namely, insertion of a meander-line seg...
Article
Full-text available
This paper presents a closely spaced two-element folded-dipole-driven quasi-Yagi array with low mutual coupling between adjacent elements. The antenna utilizes a T-junction power divider as the feeding network, with an input impedance of 50 Ω. A microstrip-stub is added to the ground plane in the middle of the two elements to improve the mutual cou...
Article
Full-text available
A dual-band, wide-beam, circularly-polarised crossed asymmetric dipole antenna is presented for global positioning system (GPS) applications. Each dipole arm has an asymmetrically barbed arrowhead and contains two different-sized printed-inductors to reduce the length of the primary radiating element and to achieve dual-band operation. At 1.575 GHz...