Перегляд за автором "Dementiev, S."

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  • Зображення мініатюри
    Публікація
    Design and Optimization of a Planar UWB Antenna
    (EWDTS, 2013) Lim, Eng Gee; Wang, Zhao; Juans, Gerry; Man, Ka Lok; Zhang, Nan; Hahanov, V. I.; Litvinova, E. I.; Chumachenko, S. V.; Mishchenko, A.; Dementiev, S.
    In this paper, we present our design on a simple, low-profile wideband planar antenna with a pure circular radiator fed by a 50 Ω microstrip line. By investigating the feeding position and ground plane dimensions, the antenna is optimized to have a very wide bandwidth that covers the whole FCC-allocated ultra-wideband (UWB) spectrum. Because of the additional patch beneath the radiator, the bandwidth can be further extended towards the lower side of the frequency spectrum. This antenna is finally modified to have a bandwidth from 2 to 12 GHz, which satisfies system requirements for S-DMB, WiBro, WLAN, CMMB and the entire UWB with S11 < -10dB. Since the Federal Communications Commission (FCC) of United States allocated the unlicensed frequency spectrum from 3.1 GHz to 10.6 GHz for commercial applications of ultra-wideband (UWB) technology in 2002 [1], ultra-wideband (UWB) technology has gained great popularity in research and industrial areas because of its high data rate wireless communication capability for various applications. As a crucial part of the UWB system, UWB antennas have been investigated extensively by researchers and numerous proposals for UWB antenna designs have been reported [2-5]. In [2], a new ultra-wideband antenna consisting of two steps, a single slotted patch and a partial ground plane is designed to operate from 3.2 to 12 GHz. In J. N. Lee’s work [3], an ultrawideband antenna composed of a modified trapezoidal radiating patch, a PI-shaped matching stub, CPW feeding, and two steps for impedance matching has been proposed for UWB applications. In [4], an ultrawideband microstrip-fed monopole antenna with a narrow slit and a modified inverted U-slot on the patch is presented. Recently, a small planar antenna fed by a microstrip line has been investigated and designed to exhibit dualband operation for Bluetooth (2.4 - 2.484 GHz) and UWB (3.1 - 10.6 GHz) bands [5]. However, many of the proposed designs employed slots or other complicated modifications in the antenna radiator and/or ground plane. These designs may pose complications during fabrication of the antenna since the tolerance of the increased special features/variables could be problematic when it goes to mass production, and instability due to the fact that complicated antenna structures may also occur in practice. Therefore, we are motivated to design a low complexity, low cost and compact antenna with wide frequency coverage supporting various applications such as Satellite Digital Multimedia Broadcasting (S-DMB), Wireless Broadband (WiBro), Wireless Local Area Network (WLAN), China Multimedia Mobile Broadcasting (CMMB) and UWB. In this paper, we present a very simple circular planar antenna with operating bandwidth ranging from 2 GHz to 12 GHz by integrating several techniques into one compact antenna. The design approach is very similar to our previously reported paper [6]. We start with a simple circular planar antenna fed by a 50Ω microstrip line with a truncated ground plane. Next, based on the study of the size of the radiator and current distribution, the antenna is designed to have an operating bandwidth covering the entire UWB band, i.e. 3.1 - 10.6 GHz. Then, the study on the size of the partial ground plane is conducted to increase the bandwidth towards the lower side of the frequency spectrum, to cover the bands for WLAN (2.4 - 2.484 GHz) and CMMB (2.635 – 2.66 GHz). With an extra patch printed on the back side of the substrate, underneath the circular radiator, the bandwidth can be further increased to cover Wibro (2.3 - 2.4 GHz) and S-DBM (2.17 -2.2 GHz) without significantly influencing other frequency bands. Thus the proposed antenna can be used for various applications such as SDMB, Wibro, WLAN, CMMB and the operating bands are evaluated using with the criterion of having return loss S11 less than 10 dB. Simulated radiation patterns over the whole frequency bands are acceptable.
  • Зображення мініатюри
    Публікація
    Quantum Modeling and Repairing Digital Systems
    (EWDTS, 2013) Baghdadi, Ammar Awni Abbas; Hahanov, V. I.; Palanichamy, Manikandan; Litvinova, E. I.; Dementiev, S.
    The results of studies concerning the models and methods of quantum diagnosis of digital systems, qubit fault simulation and analysis of fault-free behavior, as well as repair of faulty primitives, are presented.A fault is defined as each individual discrepancy of a product to specification, but fault model should never lead out the product beyond the functionality limits. Therefore fault (fault model – failure) is time fixed part of the functionality that is tied to a physical component. The constant line fault is fixed transition 0- 0 at two adjacent cycles. It makes no sense to consider it as a further extension to other cycles, because according to the automaton model they are all described by means of two adjacent time frames. By extending this two-frame concept to automaton variables we can introduce the full set of fault transitions: 00, 01, 10, 11. Indeed, if we consider the automatic variables, for instance for the register, it is necessary to generate test patterns for verifying the above transitions. Based on the concept of the fault, it follows that the total number of states of functionality also forms a complete set of faults, with the only difference being that the specific fault is always a complement to test signal that detects a fault.