CiteULike: dcastros Huang

Effective electromagnetic parameters of novel distributed left-handed microstrip lines

Shau-Gang Mao — 2008-05-09T23:56:00-00:00

Microwave Theory and Techniques, IEEE Transactions on, Vol. 53, No. 4. (2005), pp. 1515-1521.

The novel one-dimensional left-handed microstrip lines (LHMLs) consisting of the arrays of thin wires and two-layer split-ring resonators are investigated theoretically and experimentally in this paper. Unlike the conventional left-handed metamaterials for waveguides or microstrip lines, which are bulky three-dimensional constructions or require the lumped elements for high-pass configuration, this distributed structure can be directly implemented on a substrate by photolithographic techniques without soldering any chip inductors or capacitors. Moreover, it can also be easily realized at a higher frequency region by scaling the dimensions of the structure, making it highly efficient and flexible in millimeter-wave applications. To characterize the inhomogeneous LHML, the effective medium description is developed for extracting the effective electromagnetic parameters, i.e., the complex effective permittivity and permeability, as well as the refractive index. Results show that not only the simultaneously negative real permittivity and permeability, but also the antiparallel phase and group velocities may be achieved in the design passband region. In contrast to the antenna array using the conventional microstrip delay line, the LHML is incorporated in the series-fed microstrip combline array to exhibit the leading phase between the successive elements.

Curse of dimensionality and particle filters

F Daum — 2008-04-17T05:49:34-00:00

Aerospace Conference, 2003. Proceedings. 2003 IEEE, Vol. 4 (2003), pp. 4_1979-4_1993.

Adaptive OFDM synchronization algorithms based on discrete stochastic approximation

V Krishnamurthy — 2008-02-25T19:19:01-00:00

Signal Processing, IEEE Transactions on [see also Acoustics, Speech, and Signal Processing, IEEE Transactions on], Vol. 53, No. 4. (2005), pp. 1561-1574.

This paper presents discrete stochastic approximation algorithms (DSA) for time synchronization in orthogonal frequency division multiplexing (OFDM) systems. It is shown that the discrete stochastic approximation algorithms can be effectively used to achieve a significant reduction in computational complexity compared to brute force maximum-likelihood (ML) methods for OFDM synchronization. The most important property of the proposed algorithms is their recursive self-learning capability-most of the computational effort is spent at the global or a local optimizer of the objective function. The convergence of the algorithms is analyzed. An adaptive version of the discrete stochastic approximation algorithm is also presented for tracking time-varying time delays and frequency offsets in time-selective fading channels. Detailed numerical examples illustrate the performance gains of these DSA-based synchronization algorithms.

A wave-based wideband MIMO channel modeling technique

H Xu — 2008-02-19T08:19:21-00:00

Personal, Indoor and Mobile Radio Communications, 2002. The 13th IEEE International Symposium on, Vol. 4 (2002), pp. 1626-1630 vol.4.

The paper presents a multiple-input-multiple-output (MIMO) channel modeling technique for link level and system level simulations. The classical approach of wave superposition is adopted to generate MIMO channels that are statistically consistent in delay, frequency and angle domains. The paper proposes an efficient way to generate four dimensional MIMO channel transfer matrices based on standard channel statistics such as power delay profile (PDP) and power azimuth spectrum (PAS).

A miniaturized interdigital microstrip bandpass filter

Kao-Cheng Huang — 2007-11-26T20:31:03-00:00

Applied Superconductivity, IEEE Transactions on, Vol. 9, No. 2. (1999), pp. 3889-3892.

A 2.4 GHz three-stage microstrip bandpass filter was designed using a miniaturized interdigital capacitor structure to reduce the configuration in size. The filter was simulated by a finite element method software and then fabricated using TBCCO superconducting films on 20 mm×20 mm×0.5 mm MgO substrates. It was generated by photolithographic and wet etching process and packaged in a brass box. The bandwidth is 4% and the passband insertion loss of the filter was measured to be -0.4 dB at 77 K. The return loss is better than -8 dB. In particular, this filter has a sharper performance at its edge of fundamental pass band

Superconducting microstrip filters using compact resonators with double-spiral inductors and interdigital capacitors

Jiafeng Zhou — 2007-11-14T17:46:09-00:00

Microwave Symposium Digest, 2003 IEEE MTT-S International, Vol. 3 (2003), pp. 1889-1892 vol.3.

Novel resonators composed of double-spiral inductors and interdigital capacitors are developed, which not only are compact in size but also have no harmonics up to three times of the fundamental frequency. The center frequency is insensitive to the thickness of the substrate. A miniature seven-pole narrow-band HTS bandpass microstrip filter has been designed, fabricated and tested for an astronomy observation application, which requires a center frequency at 610 MHz and 0.82% fractional bandwidth. The computed and measured results are found in excellent agreement.