Yohan Lim

Multiband Folded Slot Antenna With Reduced Hand Effect for Handsets

In this letter, a multiband handset antenna using folded slots is proposed to support the five wireless communication bands of GSM850 (824-894 MHz), GSM900 (880-960 MHz), DCS1800 (1710-1880 MHz), PCS1900 (1850-1990 MHz), and UMTS (1920-2170 MHz). Since the proposed antenna has balanced resonating characteristics, resonant frequency shifting due to the hand effect is reduced while allowing a small size of 40 × 18 × 7 mm3 (W × L × H). As a result, the improved matching characteristic at the operating frequency band reduces the degeneration of the radiation efficiency due to the hand effect.

UWB wide slot antenna with band-notch function

A novel UWB wide slot antenna that has both enhanced impedance bandwidth enough to cover UWB systems and band-notch function of 5 GHz WLAN band limited by IEEE 802.11a and HIPERLAN/2 is proposed. To achieve these two characteristics of wide bandwidth and partial band-notch, a fork-shaped and tapered microstrip feed line and conductor lines in the slot are used, respectively. From the results, it is observed that wide bandwidth from 3.1 to 10.6 GHz for the VSWR<2 is achieved, while 5.15 ~ 5.825 GHz is band-notched

Parasitic-Element-Loaded UWB Antenna with Band-Stop Function for Mobile Handset Wireless USB

A UWB antenna loaded by parasitic elements for wireless USB of mobile handsets is proposed for UWB service in which a band-stop function of 5.725–5.825 GHz WLAN band is required. Two kinds of parasitic elements are incorporated into a rectangular radiator to obtain enhanced impedance bandwidth and band-stop function. The proposed antenna is very compact in size. Wide bandwidths of 3.15–4.75 GHz and 7.2–10.2 GHz are achieved while 5.725–5.825 GHz is notched. Three different shapes of conventional mobile terminals are also considered for measurement.

RCS Characteristic of Electromagnetic Gradient Surface Due to Incident Angle and Polarization

In this paper, reflection and RCS characteristic of the EGS(Electromagnetic Gradient Surface) due to incident angle and polarization is analyzed. Incident angle, , is rotated from to with steps and perpendicular and parallel polarization of incident wave are also considered each incident angle. Reflection and RCS characteristic is not much affected by variation of polarization for normal incidence(

Multi element planar inverted-F antenna for enhanced gain

{\theta}_i

A Study on the Intenna Based on PIFA with Multi Element

In this paper, we proposed the multi element PIFA with an enhanced gain characteristic. It is 35 times 15 times 5 mm3 in size so that it can be put in the A-model handset case of the S-company. The radiator of the antenna is divided into 4 elements to obtain the antenna with high gain characteristic. The divided antenna can obtain enhanced gain characteristic as currents are uniformly distributed to each element. Then, the feeding point of the antenna is modified in order to obtain a more uniform current distribution and remove opposite current as the current is directly distributed to the each element.

The design of planar and rolled fat monopole antenna for UWB radio system

In this thesis, the Multi element antenna with wideband and enhanced gain characteristic is proposed to operate at both frequency range from 824 MHz to 896 11Hz for the CDMA and frequency range from 908.5 MHz to 914 MHz for the RFID band. The proposed antenna has tile size of in order to put it in the A model of S company and each element of the proposed antenna is folded to obtain the minimum size. To obtain the antenna with wideband and high gain characteristic, the radiator of the antenna is divided into 4 elements. As a result, bandwidth of the proposed antenna become broader and lower center frequency is appeared due to increased and lengthened current path. Moreover, the enhanced gain characteristic is verified because divided element structure that induct uniform current distribution can get increased antenna efficiency. To attain more uniform current distribution, modified structure of the feeding point that can deliver currents directly is designed. The antenna that alters the feeding structure has higher gain value. Each element is folded to increase the current paths considering the current directions to attain the miniaturization of the antenna. To measure the handset antenna, the handset case must be considered. Even though antenna is designed for predicted characteristic, the resonance frequency is shifted and antenna gain is deteriorated at predicted frequency while antenna is set in the handset case. 1.08 GHz of the resonant frequency is determined after frequency shift from 150 MHz to 200 MHz is confirmed and the maximum gain is measured as 3.1 dBi while antenna is not set in the handset. In case handset case is considered, the experimental results show that the impedance bandwidth for VSWR

Improving phase continuity in electromagnetic gradient surface for large reflecting structures

In this paper, we proposed two types of antennas, planar fat monopole antenna and rolled fat monopole antenna for UWB system. The rolled fat monopole antenna is designed to reduce the size of the planar fat monopole antenna and two antennas are compared. The proposed antennas have the omni-directional pattern in azimuth. They satisfy 3.1 GHz/spl sim/7.8 band GHz for VSWR <2, using the tapered radiator and partial ground plane.

Analysis of obliquely launched plane wave steering using electromagnetic band gap (EBG)

In this paper, the method of inserting the PEC between conventional EGSs is proposed for a large reflecting structure applications. This method was designed to compensate the unrealizable reflection phase due to limitation of phase range roughly and easily. In the 2 periods EGSs using that method, reflection angle is most similar to intended value of conventional EGS which is designed to have a reflection angle of 30° for a normal incident plane wave. The design is verified in a simulation.

A Sutdy on the UWB Intenna with Band-Stop Function for Mobile Handsets

By arranging electrical gradient surface of which reflection phase is dependent on surface impedance Zs of EBG, beam steering has been realized. But because this surface impedance (Zs) strongly depends on the angle of incidence (θi) of a plane wave, furthermore, the angular dependence of the surface impedance (Zs) is different for TE and TM polarized waves, the angle of reflection cannot be calculated acutely in EGS surface when plane wave is excited obliquely. By considering the reflection phase corresponding incident angle & polarization, reflection angle can be controlled by adjusting the gradient of reflection phase across the surfaces. Using theoretical calculations and FEM simulations, it was shown that even though source wave are launched obliquely, the reflected angle was accurately calculated.