• Journal of Advanced Navigation Technology
• /
• v.21 no.1
• /
• pp.84-89
• /
• 2017

This paper presents a dual-wideband bandpass filter (BPF) with high band-to-band isolation and skirt selectivity using distributed composite right/left-handed (CRLH) transmission line (TL) quad-mode resonators (QMRs). The results of the proposed distributed CRLH TL unit cell analysis are used to establish the scattering parameters and the resonance frequencies of the QMR constituting the dual-wideband BPF. A novel dual-wideband bandpass filter is designed and fabricated, using the derived scattering characteristics. The measured results show that the fabricated dual-wideband bandpass filter has an insertion loss of less than 1.08dB in the lower band, and of 2.01dB in the upper band, a bandwidth of 2.8-5.52GHz and 9.68-12.26GHz, and a band-to-band isolation of more than 38dB, from 6.34-8.42GHz.

• Journal of electromagnetic engineering and science
• /
• v.11 no.2
• /
• pp.76-82
• /
• 2011

In this paper, a novel design for a dual-band negative group delay circuit (NGDC) is proposed. Composite right/left-handed (CRLH) ${\lambda}/4$ short stubs are employed as a dual-band resonator. A CRLH ${\lambda}/4$ short stub is composed of a typical transmission line element as the right-handed component and a high-pass lumped element section as the left-handed component. It is possible to simultaneously obtain open impedances at two separate frequencies by the combination of distinctive phase responses of the right/left-handed components. Negative group delay (NGD) can be obtained at two frequencies by using dual-band characteristics of the CRLH stub. In order to achieve a bandwidth extension, the proposed structure consists of a two-stage dual-band NGDC with different center frequencies connected in a cascade. According to the experiment performed, with wide-band code division multiple access (WCDMA) and worldwide interoperability for microwave access (WiMAX), NGDs of $-3.0{\pm}0.4$ ns and $-3.1{\pm}0.5$ ns are obtained at 2.12~2.16 GHz and 3.46~3.54 GHz, respectively.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.1
• /
• pp.314-319
• /
• 2015

The conventional geometry of a plate microstrip resonator is made up of a single metallic patch, which is printed on a monolayer dielectric substrate. Its arrangement is simple and easy to make, but it is limited in its functional abilities. Many searches have been realized to improve the bandwidth and the gain of the microstrip resonators. Among the various configurations proposed in the open literature, the stacked geometry seems to be very promising. By appropriate design, it is able to provide the operation in dual frequency mode, wide bandwidth enough and high gain. The theoretical investigations of structures composed of two stacked anti-reflection coatings, enhanced metallic coatings are available in the literature, however, for the stacked configurations involving three metallic coatings or more, not to exact or approximate analysis was conducted due to the complexity of the structure.

• ETRI Journal
• /
• v.35 no.2
• /
• pp.188-192
• /
• 2013

Previous work proposed combining multipulse pulse position modulation (MPPM) with pulse amplitude modulation to form multipulse amplitude and position modulation (MPAPM), which is a hybrid modulation that results in an improvement in bandwidth efficiency but a degradation in power efficiency. In this paper, to achieve greater power efficiency and a better data rate, we propose multipulse dual amplitude-width modulation, based on MPAPM and pulse width modulation. The proposed scheme shows a remarkable improvement in data rate and a 1.5-dB improvement in power efficiency over MPAPM, while sustaining the bandwidth efficiency. After introducing symbol structure, we present the theoretical expressions of spectral efficiency, the power requirements, and the normalized data rate, as well as the results of comparing the proposed modulation to MPPM and MPAPM.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.40 no.11
• /
• pp.93-98
• /
• 2003

In this paper, we designed a printed square loop antenna for operating of PCS and IMT2000 band. The proposed antenna has omni-directional radiation patterns with broad bandwidth, similar to the conventional antenna, to easy feed on composing single planar. We obtain an ideal impedance matching and increase bandwidth. An antenna bandwidth is about 150MHz(1.74∼l.89〔GHz〕) at 1$^{st}$ resonance frequency and 290MHz(1.95∼2.24GHz) at 2$^{nd}$ resonance frequency on VSWR(equation omitted)1.5, and then we can obtain not only 1.73∼l.87 〔GHz〕 PCS band but also 1.92∼2.17 (GHz) IMT2000 band. band.

• Journal of Korea Multimedia Society
• /
• v.6 no.1
• /
• pp.128-135
• /
• 2003

A fairness control method for Distributed-Queue Dual-Bus(DQDB) has been studied under specific traffic types such as equal probability traffic, symmetric traffic and asymmetric traffic. To distribute DQDB network bandwidth fairly to all stations under general traffic such as a client-server traffic that differs from specific traffic types, we propose an effective fairness control method. Based on an access limit, the proposed mechanism applies two bandwidth control mechanisms to DQDB networks. One is the mechanism that is called APS(Access Protection Scheme) for servers. And another is the mechanism that controls the allocation of bandwidth only using an access limit lot clients. Simulation results show that it outperforms other mechanisms.

• Journal of KIISE:Information Networking
• /
• v.28 no.3
• /
• pp.435-446
• /
• 2001

In this paper, a new fairness control method is proposed to distribute DQDB-SR (Distributed-Queue Dual-Bus with Slot Reuse) network bandwidth fairly to all stations on client-server environments. By using an access limit that follows a characteristic of client-sever load patterns and a bandwidth borrowing and returning mechanism, the proposed mechanism imparts fairness bandwidth control capability to DQDB-SR. To implement the proposed mechanism, we find the optimal placement of erasure nodes that maximizes network capacity for DQDB-SR, and calculate the access limit. At overload conditions, simulation results show that the proposed mechanism does not deteriorate network throughput, and outperforms other fairness control mechanisms in a success rate and an average packet transfer delay.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.12 no.3
• /
• pp.329-338
• /
• 2001

In this paper, we designed microstrip patch antenna to enhance the weak point of general microstrip patch antenna that has narrow bandwidth and analyzed that. To reduce reactance in probe feed antenna, capacitive gap added to the patch. Using single patch and auxiliary wire, makes dual frequency resonant. So bandwidth is improved and gain also becomes higher. To verify with experiment, PCS band antenna is designed, fabricated. For PCS band antenna, bandwidth is 180 MHz in VSWR<1.5 and gain is 8.6 dBi.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.18 no.6
• /
• pp.233-240
• /
• 2019

In this paper, due to the development of 5G communication technology, an antenna capable of covering both LTE and 5G bands is currently needed. In addition, we designed and manufactured a single feed antenna for the integrated public network (LTE) and 5G frequency dual band cover to satisfy the frequency bandwidth of more than 10% in each band. The antenna designed by adopting the dipole of the basic dipole antenna in a planar structure is a form in which the radiating element is vertically extended at all of the 700 MHz antennas and folded into a 'ㄷ' shape. In addition, the radiating element of the 700MHz band serves as a reflector of the 3.5GHz band radiating element. As a result, the 700 MHz band -10 dB bandwidth 104 MHz(14.8%) and 3.5 GHz band -10 dB bandwidth 660 MHz(18.8%) were obtained and the radiation pattern characteristic resulted in gains of 8.46 dBi, beam width E-plane 55°, H-plane 81° and 3.5 GHz bands 6.14 dBi, beamwidth E-plane 79°, H-Plane 49°.

• Proceedings of the Korea Society for Industrial Systems Conference
• /
• 2001.05a
• /
• pp.237-246
• /
• 2001

In this paper we introduce a solution to improve the unfairness problem and to remove the waste of bandwidth in the distributed queue dual bus system. This solution requires only a minor modification of the current protocol and further shows no bandwidth wastes when we try to resolve the unfairness problem occurred in current DQDB protocol. There has been many problem in DQDB system in terms of fairness of sending message in each node. In order to solve this problem, Bandwidth Balancing technic and proportional assignment technic have been introduced. It is, however, to note that the waste of bandwidth problem is still existing in those technics, even though there has been significant improvement as to the fairness problem. In this paper we introduce a new solution to remove the waste of bandwidth problem while we are still obtaining the improved fairness of the network. By following this new solution, the simulation result shows higher throughput and lower message delay than previously proposed technics.