Che-Young Kim

Design of the Ultrawideband Antenna with a Quadruple-Band Rejection Characteristics Using a Combination of the Complementary Split Ring Resonators

In this paper, the design method of a quadruple-band rejection ultra-wideband (UWB) antenna with three co-directional complementary split ring resonators (CSRRs) is proposed. Within the design step, individual antennas corresponding to each rejection band is flrst designed, and then a flnalized structure is determined by assembling these individual antennas altogether. The shape of the flnal antenna achieves both the impedance matching of ultra-wideband and the respective resonances at four rejection bands. Here, the mutual coupling among the band rejection elements is minimized, and the placement of the resonators is optimized. The fabricated antenna is compact enough to be integrated into the UWB system, and also the measured results show the validity of the proposed design strategy.

Design of the Novel Band Notched UWB Antenna with the Spiral Loop Resonators

In this paper, a novel conflguration of circular ultra-wideband (UWB) antenna with band rejection characteristic is presented. In order to obtain this characteristic, the spiral loop resonators resonating at the rejection frequency are located in both sides of the circular radiating patch. This novel structure provides the band-notched characteristic without the degradation of the UWB antenna performance itself. Furthermore, the notched band can be easily tuned by adjustment of resonator dimension because the size of the spiral loop resonators controls the corresponding resonance frequency. This prototype antenna has been fabricated on a substrate, Rogers 4003, with the thickness of 0.8mm and relative permittivity of 3.38. The fabricated UWB antenna covers the frequency band from 3.1 to 11.23GHz (S11 • i10dB), and the band rejection characteristic appears near at 5.8GHz band to which the wireless LAN service is assigned. And the far-fleld radiation patterns of the proposed antenna show omnidirectional and stable over the whole frequency band, which prospects the deployment in the UWB system. The measured results agree well with the simulation by the Microwave Studio of CST. This novel technique utilizing the spiral loop resonators might be useful to the planar antennas requiring the band rejection characteristics.

A Compact Band Notched UWB Antenna for Mobile Applications

In this paper, a compact circular UWB (ultra-wideband) antenna with WLAN 802.11a/n band (5.15»5.825GHz) rejection characteristic is proposed for the mobile applications. The proposed UWB antenna was compact enough to be loaded into a mobile handset. The performance of the suggested antenna is mostly dependent on the gap between circular radiator and the ground plane. In order to have the band notched operation, the CSRR (complementary split ring resonator) is etched inside the circular patch of the UWB antenna. MWS (Microwave Studio) of CST company was utilized in the design stage. The antenna was constructed on a substrate, Rogers 4003, with the thickness of 0.8mm and relative permittivity of 3.38. A size of substrate is 24£37.5mm 2 and a radius of circular radiator is 5mm long. The proposed antenna covers the frequency band from 3.2 to 10.6GHz (S11 • 10dB), and the band rejection occurs about 5.7GHz band. A simulation shows the maximum gain of 5.2dBi, and radiation pattern is nearly omni-directional over the entire i10dB return loss bandwidth. It also represents the group delay below 1nsec over UWB communication band (3.2GHz»10.6GHz) except WLAN band. Based on the experimental results, the proposed antenna could be a good candidate for the handheld mobile handsets.

Flexible Hilbert-Curve Loop Antenna Having a Triple-Band and Omnidirectional Pattern for WLAN/WiMAX Applications

A triple-band flexible loop antenna is proposed for WLAN/WiMAX applications in this paper. The proposed antenna is formed by the third-order Hilbert-curve and bending type structure which provides flexible characteristics. Even though the radius of the curvature for bending antennas is changed, a triple-band feature still remains in the proposed antenna. Moreover, the antenna exhibits the characteristics of omnidirectional radiation pattern and circular polarization. To verify the receiving performance of antenna, a simulation on the antenna factor was conducted by an EM simulator. Based on these results, the suggested antenna makes a noteworthy performance over typical loop antennas.

A NUMERICAL SOLUTION FOR THE ROUND DISK CAPACITOR BY USING ANNULAR PATCH SUBDOMAINS

A numerical method is presented for determining the static charge distribution and capacitance of a round disk capacitor. Based on equivalent surface charge distributions, an integral equation subject to the boundary conditions is transformed into an algebraic equation by using the method of moments. In the proposed scheme to eliminate the discretizing errors often encountered in other techniques, annular patch subdomains are introduced, not only to improve the accuracy of solutions, but also to reduce the matrix size of the resultant equation. By solving the transformed algebraic equation, the charges per unit area on the interfaces are numerically determined. With use of the free charge on plates obtained by using annular patches, the capacitance is more accurately calculated. The equipotential lines around a round disk capacitor are also calculated. In order to show the usefulness of this method, the employed scheme is applied to a single circular disk with an exact solution, and to the dielectric filled capacitor partially covered by plates. Those results are examined and discussions are also made to support the validity of the presented scheme.

Compact Ultra-Wideband Antenna with Quadruple-Band Rejection Characteristics Using SRR/CSRR Structure

Abstract This article presents a compact ultra-wideband (UWB) antenna with quadruple-band rejection characteristics. Fundamentally, small antennas possess many weaknesses such as spatial limitations and coupling problems. To overcome the spatial constraints of the compact antenna, the split ring resonator (SRR) and complementary split ring resonator (CSRR), which function as band-rejection elements are inserted into the antenna. Applying two-ring gaps of the SRR and CSRR in an intelligent way allows us to circumvent coupling limitations of the classical UWB antenna, while the antenna covers the frequency band from 3.1 to 10.6GHz but nullifies the quadruple bands. Experimental results show that the proposed antenna can serve in UWB systems.

Design and Fabrication of UWB Antenna Using the SRR for WLAN Band Rejection

In this paper, a novel UWB(Ultra Wide-band) antenna with suppressed band of IEEE 802.11a() WLAN was designed and fabricated by using SRR(Split Ring Resonator) with band rejection property. MWS(Micro-wave Studio) of CST company was utilized in the design stage. The antenna was fabricated on a substrate, Rogers 4003, with the thickness of 0.8 mm and relative permittivity of 3.38. The measured result shows that the proposed antenna has a good return loss below -10 dB and group delay below 1nsec over UWB communication band() except WLAN band. It also shows the omni-directional radiation pattern.

Modified cavity-backed 4-arm spiral antenna for GPS

In this paper, a modified cavity-backed spiral GPS antenna is proposed. The presented antenna consists of a modified four-arm Archimedean spiral, an absorber and a cavity which is fed by ut-47 cables. In order to confirm the broadband characteristic, S-parameter result at 1-2GHz is calculated. The gain for mode 1 and mode 2 of the antenna at 1.575GHz, is 0.9dB and -8.7dB respectively. The axial ratio is below 1.25dB between the range of ±45o, which validates circular polarization characteristic. Moreover, the performance of the proposed antenna is verified through the current distribution also.

Design of Dual Band-Notched UWB Antenna with the Hilbert-Curve Slots

In this letter, a planar monopole UWB antenna with dual band-notched characteristics is proposed. The band-stop characteristics is realized by embedding the 1st/3rd order Hilbert-curve slots on the patch. With the dimension adjustment of each Hilbert-curve slots, the band rejection from 3.3 to 3.7 GHz and from 5.3 to 6 GHz can be accomplished easily. The VSWR and radiation pattern of the fabricated antenna are measured, and the proposed antenna would be adequate to a UWB applications.

Regulatory radiation limit of intermodulation interference between AMPS receiver and low power radio devices

In recent years, the use of the low power radio devices has been arisen in various fields. The emergence of several radio devices may lead to signal interference and result in system performance degradation when these devices share the same environment, including co- channel and adjacent channel. Thus it is essential to develop the anticipation model and to quantify the level of interference against the interferer to reduce the degradation. In this paper, we predicted the level of electric field strength radiated from the low power radio devices and analyzed interference mechanism by using the intermodulation interference. As a target device, AMPS receiver was considered because it is known as a generic module radio. Thereby, the outcome of paper may be applicable to any other radio devices possessing a similar circuit with that of AMPS receiver.