CiteULike: dcastros Cui

A novel metamaterial-inspired electrically small antenna fed by CPW

Meng Li — 2008-07-24T12:21:02-00:00

Microwave and Millimeter Wave Technology, 2008. ICMMT 2008. International Conference on, Vol. 4 (2008), pp. 1613-1616.

This article presents the design of an inexpensive, efficient, and electrically small antenna based on metamaterial- inspired structure fed by the coplanar waveguide (CPW). The size of the proposed antenna is 12 mm x 12 mm with the resonant frequency of 1.47 GHz. Details of the proposed antenna are presented, with full-wave simulation results to support the design.

Power delay profile and noise variance estimation for OFDM

T Cui — 2008-05-22T19:46:18-00:00

Communications Letters, IEEE, Vol. 10, No. 1. (2006), pp. 25-27.

In this letter, we present cyclic-prefix (CP) based noise-variance and power-delay-profile estimators for Orthogonal Frequency Division Multiplexing (OFDM) systems. Signal correlation due to the use of the CP is exploited without requiring additional pilot symbols. A heuristic estimator and a class of approximate maximum likelihood (ML) estimators are proposed. The proposed algorithms can be applied to both unitary and non-unitary constellations. These algorithms can be readily used for applications such as minimum mean-square error (MMSE) channel estimation.

Arbitrarily dual-band components using simplified structures of conventional CRLH TLs

Xian Lin — 2007-11-05T20:33:09-00:00

Microwave Theory and Techniques, IEEE Transactions on, Vol. 54, No. 7. (2006), pp. 2902-2909.

Microwave components with nonlinear phase responses are developed using a simplified composite right/left-handed (CRLH) transmission-line (TL) structure without the series capacitance or the shunt inductance. Using such a simplified CRLH structure, arbitrarily dual-band microstrip components have been realized in compact sizes such as a quarter-wavelength short-circuited stub and dual- band branch-line couplers. Simulation and measurement results are given to demonstrate the efficiency and good performance of the proposed components. For the quarter- wavelength short-circuited stub based on the simplified CRLH-TL structure without the series capacitance, it has been shown that the insertion loss is less than -0.1dB. For the arbitrarily dual-band branch-line coupler, experiment results exhibit that S/sub 21/ and S/sub 31/ are larger than -3.6dB, the isolations are smaller than -30dB, the return losses are smaller than -20dB, and the phase differences are within 90/spl deg//spl plusmn/1.8/spl deg/.

Compact Resonator Filters and Power Dividers Designed with Simplified Meta-Structures

Lin — 2007-09-16T04:23:41-00:00

Journal of Electromagnetic Waves and Applications, Vol. 21, No. 12. (2007), pp. 1663-1672.

Realization of arbitrary dual-band components using an improved CRLH transmission-line model

Xian Lin — 2007-11-02T17:41:40-00:00

Microwave Conference Proceedings, 2005. APMC 2005. Asia-Pacific Conference Proceedings, Vol. 1 (2005), 4 pp..

In this paper, new structures with nonlinear phase responses are proposed based on the composite right /left-handed (CRLH) transmission lines. Using such improved CRLH structure, arbitrary dual-band microstrip components have been realized, such as a quarter-wavelength open/short-circuited stub, and a dual-band branch-line coupler, etc. This has been demonstrated by both simulated and measured results. Compared to the conventional CRLH structures, the novel components are more compact and are easier to be realized.

A New Metamaterial Structure to Amplify Evanescent Waves and Its Applications in Microwave Components

Tie Cui — 2007-10-24T10:20:52-00:00

Antenna Technology: Small and Smart Antennas Metamaterials and Applications, 2007. IWAT '07. International Workshop on (2007), pp. 527-527.

Summary form only given. In this talk, we present a new structure to amplify the evanescent waves. The structure is composed of two layers. The first layer is realized by a periodic structure with unit cell of series inductor and shunt capacitor (LC), and the second layer is realized by a periodic structure with unit cell of series capacitor and shunt inductor (CL). We show that both the LC and CL structures are equivalent to the crystal bandgap metamaterials, whose equivalent permittivity and permeability have been derived. Under certain frequency bands, evanescent waves are supported in both LC and CL structures. When such two structures are cascaded together to form a bilayer, we show that evanescent waves existing in two single layers can be amplified exponentially if the resonant conditions are satisfied. Such resonant conditions are equivalent to the anti-matching conditions for the permittivity and permeability of the crystal bandgap metamaterials. We present circuit-simulation results of the LC and CL structures arid theoretical predictions of the equivalent crystal bandgap materials, which have excellent agreements. From the simulation results, we clearly observe the exponentially increasing and decreasing distribution of electric field. We further propose an experiment using lumped capacitors and inductors mounted on a printed circuit board to verify the EWA phenomena. The EWA feature in the LC-LC structure can find important applications in the new-concept microwave components, for example, the extremely-narrow band filters.