Jeongpyo Kim

Design of an ultra wide-band printed monopole antenna using FDTD and genetic algorithm

This letter presents an ultra wide-band (UWB) antenna with a printed monopole structure fed by a coplanar waveguide (CPW) line. The antenna is analyzed by using the finite-difference time-domain (FDTD) method and genetic algorithm (GA) to achieve an ultra wide bandwidth characteristic. The measured frequency response shows an impedance bandwidth of 7.25GHz or 104.7% over 3.3 to 10.55GHz for VSWR less than 2.

A Tunable Internal Antenna With an Epsilon Negative Zeroth Order Resonator for DVB-H Service

A tunable internal antenna with an epsilon negative zeroth order resonator (ENG-ZOR) for digital video broadcasting-handheld service is proposed in this paper. The antenna consists of two helical radiators, an ENG ZOR with two inductors and a variable capacitor to adjust the resonant frequency. The resonant frequency of the designed antenna can be swept from 474-702 MHz by adjusting the capacitance of the variable capacitor by controlling the DC bias voltage. The proposed antenna has a very compact size of 40 mm times 5 mm times 5 mm.

A stair-shaped CPW-fed printed UWB antenna for wireless body area network

In this paper, a CPW-fed ultra-wideband antenna for wireless body area network is proposed. The proposed antenna has a stair-shaped structure printed on the top of a substrate with the dielectric constant of 4.4 and occupies a small volume of 36mm × 24 mm × 1 mm. The antenna has an impedance bandwidth of 8 GHz from 3 to 11 GHz. The variation of group delay between the two proposed antennas is less than 1.09 ns and the maximum gain variation is about 6.5 dB. The radiation pattern over the frequency band of interest is changed from near omni-directional to directional pattern when the antenna is placed on the body.

Dual band MIMO antenna using ENG zeroth order resonator for 4G system

We propose a two-element diversity-antenna array using epsilon negative zeroth order resonator (ENG-ZOR) at the long-term evolution (LTE) and Wibro (WiMax in Korea) bands for the multiple-input multiple-output (MIMO) application. Each element is designed by utilizing an ENG ZOR unit cell with size of 10 mm × 6 mm × 6 mm. The lower resonant frequency is fixed by the zeroth order resonance of the ENG ZOR and the higher is selected by the radiator utilizing the first order resonance of the ENG ZOR. An isolator is added between the two elements in order to enhance the isolation characteristic at higher band of the designed MIMO antenna. The MIMO antenna is fabricated on the top side of the ground plane with size of 48 mm × 108 mm × 0.4 mm. The fabricated antenna has the isolation of about 20 dB at the lower band and higher than 13 dB at the higher band.

Design of a new DFT filter bank with modified sampling kernels and its application to arbitrary image scaling

A new M-channel DFT filter bank with its analysis and synthesis parts being modified is proposed for arbitrary image scaling, whereby down/up sampling kernels are newly introduced along with a compactly supported sampling function of degree 2. In particular, while only an even number of channels is allowed in the conventional MDFT FB, arbitrary (even/odd) number of channels can be applied in the proposed approach. Furthermore, it is shown that images of arbitrary size can be obtained from an original image without changing the number of channels. Finally, simulation results demonstrate that high-quality images of arbitrary size can be achieved by the proposed approach.

Tunable Internal Loop Antenna for DVB-H Service

In this paper, we proposed a tunable half loop antenna with two inductors and variable capacitance. To achieve the wide bandwidth required for DVB-H service, a variable capacitor is added between the transmission line and ground. In addition, the antenna gain is improved by using helical radiators. Even though the proposed antenna has very compact size of 40 mm x 5 mm x 5 mm, its gain is about 4 dB higher in average than reference gain. Due to the small size and simple structure properties, it can be a very attractive candidate for DVB-H application.

Arbitrary scaling of images using an M-channel DFT filter bank with optimized adaptive interpolation kernels

A new approach to arbitrary scaling of high quality images is proposed, whereby a 2-D M-channel DFT filter bank is designed along with its synthesis part being modified on the basis of a compactly supported sampling function. For that purpose, the 2-D down/up-sampling formulae in a closed form are derived and utilized. Also, an optimized adaptive interpolation technique is employed to compensate for quality degradation arising in scaled images. Finally, simulation results demonstrate that high quality images of arbitrary size can be obtained from the original image.

Design of a small resonant antenna using metamaterial based on transmission line approach

In modern wireless devices, a compact size antenna is required due to the limited space available for an antenna. Since the experimental verification of metamaterial [1], much studies have been performed on small antenna using metamaterial. Recently, composite right/left-handed (CRLH) resonant antennas have become of particular interest. In this paper, a CRLH resonant antenna using interdigital capacitor (IDC) and complementary split-ring resonator (CSRR) is proposed, and the transmission line (TL) approach is adopted for the analysis.

Design and Fabrication for T-DMB Active Type Antenna

In this paper, An active antenna of T-DMB was developed to equip to handhold gadgets by using LNA and a parasitic element allowing to miniature. The size of the fabricated active antenna is and FR4 is used for the substrate. The size of the proposed antenna is reduced by 38.8% at the operating frequency compared to one without a parasitic element, and a short stub. The proposed antenna shows improved performance at the measurement especially in the ratio of S/N compared with conventional monopole of 300 mm. The proposed antenna is well able to adapt into handhold gadgets for receiving T-DMB.

Circularly Polarized Microstrip Patch Antenna Using Artificial Magneto-Dielectric Substrate with Grid Structure

We propose a circularly polarized microstrip patch antenna that use an artiflcial magneto-dielectric (AMD) substrate. The proposed antenna has a square patch with dual feeding points and uses a Wilkinson power divider in order to achieve a circularly polarized radiation pattern. The AMD substrate is constructed with a two-dimensional array of single split ring resonators. The antenna has an axial ratio of less than 1.7dB, peak gain of 0.55dBic, and exhibits a right handed circular polarized radiation pattern at Korean UHF RFID service band. The size of the antenna is 100mm £ 100mm £ 5:2mm and the radiating patch measures 65mm£65mm (0:199‚0£0:199‚0).