Yong-Seek Chung

Compact UWB Antenna With I-Shaped Band-Notch Parasitic Element for Laptop Applications

A compact ultrawideband (UWB) antenna with a band-notch function is proposed for laptop applications. The band-notch function is realized by a half-wavelength parasitic element printed on the rear side of the substrate. The impedance bandwidth (VSWR < 2) of the antenna is 3.1 ~ 11.4 GHz (114%) with a notched frequency from 5.05 to 5.90 GHz. The antenna has a fairly good omnidirectional pattern, and the average gain is -3.0 ~ -1.2 dBi over the UWB frequency band except for the notched frequency band. The performance of the proposed antenna is confirmed by simulation and measurement results.

Internal dual-band WLAN antenna for laptop applications

This paper presents a dual-band (2.4 GHz, 5.2/5.8 GHz) WLAN antenna for laptop applications. The proposed antenna consists of the folded-dipole structure operated at higher band and two arms operated at lower band. The radiation pattern of a proposed antenna is orthogonal to that of a conventional monopole at all operating frequency bands.

Multi-band diversity antenna for mobile handset applications

A diversity antenna for a tri-band application is proposed and designed. The proposed diversity antenna consists of two wideband planar inverted-F antennas (PIFAs) and a suspended line between two PIFAs. The measured results show that the proposed antenna has a wide impedance bandwidth (37%) enough to serve a triple band (PCS, UMTS and WiMAX), a high radiation efficiency (> 50%), and a low correlation coefficient (< 0.2).

Enhanced isolation between donor antenna and coverage antenna for indoor WCDMA repeater systems

This paper presents a structure of the Frequency Selective Surface (FSS) to improve the isolation between donor antenna and coverage antenna for indoor WCDMA repeater systems. The repeater system has two linearly polarized antennas backed with the reflectors. The proposed FSS is embedded into reflectors aligned with the cross-polarization of each antenna. The isolation with the FSS is enhanced overall more than 6 dB at WCDMA band, compared to that without the FSS.

Electrically small loop antenna for UHF band RFID tag

UHF band RFID tag antenna which has a similar radiation pattern of the electrically small loop antenna is presented. The structure of the proposed tag antenna is a small circular dipole array on the xy-plane, and the antenna is fed by inductively coupled loop to flow a uniform amplitude and in phased current along its circumference. Since its radiation pattern has an omnidirectional pattern in the xy-plane, the proposed tag antenna can reduce the interference among adjacent tag antennas arranged parallel to xy-plane.

Investigation of Electromagnetic Field Coupling with Twisted Conducting Line by Expanded Chain Matrix

In the current paper, we propose a new modeling algorithm to analyze the coupling between an incident electromagnetic field (EMF) and a twisted conducting line, which is a kind of non-uniform line. Typically, analysis of external field coupling to a uniform transmission line (TL) is implemented by the Baum-Liu-Tesche (BLT) equation so that the induced load responses can be obtained. However, it is difficult to apply this method to the analysis of a twisted conducting line. To overcome this limitation, we used a chain matrix composed of ABCD parameters. The proposed algorithm expands the dimension of the previous chain matrix to consider the EMF coupling effectiveness of each twisted pair, which is then applied to multi-conductor transmission line (MTL) theory. In addition, we included a comparative study that involves the results of each method applied in the conventional BLT equation and new proposed algorithm in the uniform two-wire TL case to verify the proposed method.

Compact PIFA / slot antenna for quad-band mobile handset applications

An internal PIFA/slot antenna for quad-band mobile handset applications is presented. The quad-band operation for the bar-type mobile handset is obtained by the resonant modes of the slot antenna in conjunction with those of the PIFA. The proposed antenna has a compact size of 42×10×4 mm³. The quad-band operation includes GSM850 (824–894 MHz), GSM900 (880–960 MHz), DCS1800 (1710–1880 MHz), and PCS1900 (1850–1990 MHz).

Internal antenna for UHF-band mobile RFID system

UHF-band radio frequency identification (RFID) antenna for mobile handset applications is presented. The proposed antenna consists of a radiating element and a parasitic element connected to the ground plane. The radiation pattern of proposed antenna is orthogonal to that of a monopole antenna. The impedance bandwidth (902 MHz ~ 923 MHz) covers a Korea mobile RFID service (908.55 MHz ~ 913.95 MHz). The measured antenna peak gain is -0.37 dBi at 911 MHz.

Covariance matrix synthesis using maximum ratio combining in coherent mimo radar with frequency diversity

Reliable detection and parameter estimation of a radar cross section(RCS) fluctuating target have been known as a difficult task. To reduce the effect of RCS fluctuation, various diversity techniques have been considered. This paper presents a new method for synthesizing a covariance matrix applicable to a coherent multi-input multi-output(MIMO) radar with frequency diversity. It is achieved by efficiently combining covariance matrices corresponding to different carrier frequencies such that the signal-to-noise ratio(SNR) in the combined covariance matrix is maximized. The value of a synthesized covariance matrix is assessed by examining the phase curves of its entries and the improvement on direction of arrival(DOA) estimation.

Analysis of Bistatic Clutter Structure through Simulation

Generally, bistatic clutter, contrary to the monostatic clutter, has nonlinear structure in Angle-Doppler domain due to the noncooperative motion of the transmitter and the receiver. In this paper, we first simulate the bistatic clutter structure resulting from the relative motion of the transmitter and the receiver and then analyze their relations through the bistatic clutter structure in Angle-Doppler domain. Also, we show the operation condition of the transmitter and the receiver leading to low rank of a covariance matrix of the bistatic clutter.