Ji-Chyun Liu

CPW-Fed Dual-Mode Double-Square-Ring Resonators for Quad-Band Filters

We propose the improved CPW-fed configurations with dual-mode double-square-ring resonators (DMDSRR) for quad-band applications. The resonant frequency equations of DMDSRR are introduced for simply designing quad-band bandpass filter (BPF). Resonant frequencies can be controlled by tuning the perimeter ratio of the square rings. To obtain lower insertion loss, higher out-of-band rejection level and wider bandwidth of quad-band, the improved CPW-fed and dual-mode perturbations are designed. The proposed filter is successfully simulated and measured. It can be applied to 0.95, 1.26, 1.89 and 2.29 GHz systems.

CPW-Fed Circular Fractal Slot Antenna Design for Dual-Band Applications

Using configuration synthesis and design map, the CPW-fed circular fractal slot antennas are proposed for dual-band applications. In practice, the experimental results with broadband and dual-band responses (47.4% and 13.5% bandwidth) and available radiation gains (peak gain 3.58 and 7.28 dBi) at 0.98 and 1.84 GHz respectively for half-wavelength design are achieved firstly. Then, the other broadband and dual-band responses (75.9% and 16.1% bandwidth) and available radiation gains (peak gain 3.16 and 6.62 dBi) at 2.38 and 5.35 GHz for quarter-wavelength design are described herein. Contour distribution patterns are applied to figure out the omni-directional patterns. The demonstration among the design map and the EM characteristics of the antenna is presented by current distributions.

Single-Feed Circularly Polarized Aperture-Coupled Stack Antenna With Dual-Mode Square Loop Radiator

The authors propose a compact single-feed stack antenna consisting of a square loop radiator with perturbation, an aperture-coupled structure, and a straight-strip feed line for circular polarization (CP) and unidirectional radiation applications. This perturbation applies both dual-mode and orthogonal-mode effects simultaneously in the square loop resonator to present bandwidth and CP characteristics. The stack antenna presents the desired axial ratio (AR) bands of 2.42 GHz with 3-dB bandwidth (BW) = 62 MHz (2.5%). The circular polarization is demonstrated with AR spectrum and orthogonal modes distributions. The proposed antenna is successfully simulated and measured with frequency responses, radiation patterns, and current distributions.

MINIATURIZED DUAL-MODE RESONATORS WITH MINKOWSKI-ISLAND-BASED FRACTAL PATCH FOR WLAN DUAL-BAND SYSTEMS

The miniaturized dual-mode dual-band band-pass fllters (BPF) using Minkowski-island-based (MIB) fractal patch resonators are proposed in this paper. The BPF is mainly formed by a square patch resonator in which a MIB fractal conflguration with 2nd order iteration is embedded in the patch. By perturbation and inter- digital coupling, the wide-band and dual-band responses are obtained respectively. For miniaturized wide-band design, at 2.41GHz central frequency it has good measured characteristics including the wide bandwidth of 2.26{2.56GHz (3-dB fractional bandwidth of 12.4%), low insertion loss of 0.72dB, high rejection level (i52:5/i44:9dB), and a patch size reduction with 60.6%. For compact dual-band design, the proposed fllter covers the required bandwidths for WLAN bands (2.20{2.96GHz and 4.74{5.85GHz). The patch size reduction of 78.1% is obtained. Two transmission zeros are placed between the two pass- bands and resulted in good isolation.

An Improved Equivalent Circuit Model for CSRR-Based Bandpass Filter Design With Even and Odd Modes

We present a new equivalent circuit model that incorporates the resonances and transmission zeros in terms of even and odd modes for CSRR-based bandpass filter (BPF) design. The circuit model and three resonance characteristics are consistent with the geometry of the CSRR-based BPF. The variations of distance ratio, related gap and loop number are investigated. The good performance of lower insertion loss (0.87 dB), deeper and symmetric transmission zero level (- 53.20 dB) , wider bandwidth (fractional BW 89.4%) and wider stopband (extended to 2.9 f0 below - 28.5 dB rejection level) at the central frequency f0 = 1.88 GHz are achieved by this methodology.

A DUAL-MODE APERATURE-COUPLED STACK ANTENNA FOR WLAN DUAL-BAND AND CIRCULAR POLARIZATION APPLICATIONS

A compact stack antenna consisting of square loop resonators, aperture couples, feed line and the perturbation for dual- band and circular polarization (CP) applications is proposed in this paper. This perturbation applies both dual-mode and orthogonal mode efiects existing in the square loop resonator to present wide-band and CP characteristics simultaneously. The stack antenna presents the desired bands of 2.46GHz with bandwidth (BW) = 160MHz (6.58%) and 5.28GHz with BW = 450MHz (8.52%). The circular polarizations for dual-band are demonstrated with axial ratio (AR) spectrum and orthogonal modes. The proposed antenna is successfully simulated and measured with frequency responses, radiation patterns and current distributions.

AN INDUCTIVE SELF-COMPLEMENTARY HILBERT-CURVE ANTENN FOR UHF RFID BROADBAND AND CIRCULAR POLARIZATION TAGS

A novel fractal tag antenna constructed with Hilbertcurve and self-complementary configuration is proposed for UHF RFID applications. The main aim of this paper is to merge the meander line and meandered-slot structure of the RFID tag antenna in order to obtain a good performance of compact, broadband, circular polarization and conjugate impedance matching. The tunable inductive and broadband (−10 dB BW = 115 MHz) characteristics Corresponding author: J. C. Liu (jichyun@cyu.edu.tw).

DMSLR-Based Bandpass Filter With Hilbert-Curve Perturbation for Multiple Resonances and Wideband Applications

The dual-mode square loop resonator with Hilbert-curve perturbation is introduced for multiple resonances and wideband filters in this letter. To obtain low insertion loss (0.5 dB), high out-of-band rejection level (-49.51 dB) and wider band (BW 65%) filters, iterative Hilbert-curve perturbation and space-filling technique are proposed. Multiple resonances that included dual modes, third, fourth, and fifth order resonances are presented with resonance splitting plots. Surface current distributions with multiple resonances and transmission zeros are presented and discussed.

Analysis of Interactions Among Two Tropical Depressions and Typhoons Tembin and Bolaven (2012) in Pacific Ocean by Using Satellite Cloud Images

This paper presents a framework for using remote sensing imagery and image processing techniques to analyze the interactions among tropical depressions (TDs) and typhoons. The purpose is to properly understand and predict this phenomenon, in order to reduce their influence on the regions where they pass by. Improvements on the understanding of the interactions among TDs and typhoons are obtained and presented. They carry the potential to improve forecast of severe weather system. In this paper, we analyzed the physical responses of TDs on two typhoons Tembin and Bolaven (2012), including TDs appearance, development, interaction, and mergence. According to the Central Weather Bureau of Taiwan, Tembin and Bolaven were formed about 1550 km apart. In general, the Fujiwhara effect happens when two storms are within a distance of 1400 km. Does the TD have impacts on the typhoons, and could we also call this impact as Fujiwhara effect? The 3-D profiles of the weather systems are reconstructed using the multifunctional transport satellite (MTSAT) infrared cloud images by the image reconstruction technique (IRT). The 3-D profiles of typhoons were implemented for investigating the in-depth distribution of the cloud top from a surface cloud image. The main parameters, which have been analyzed in this paper, are distance, height difference, rotation, and sizes of the two TDs and the two typhoons. The results showed that two TDs occurred between typhoons Tembin and Bolaven, which interacted with each other through upward convection and attraction between two typhoons and the TDs, respectively. The mergence of the two TDs caused the typhoons to start rotating and generate strengthened power. The findings of the TD effects on two typhoons represent a new aspect of the interaction between TD and typhoon.

Comments, with reply, on "Optimum noise measure terminations for microwave transistor amplifiers" by C.R. Poole and D.K. Paul

The commenters point out typographical errors in equations (5) and (6) of the above-titled paper by C.R. Poole and D.K. Paul (ibid., vol. MTT-33, no.11, pp.1254-1257, Nov. 1985). They also purport to show that some calculations for the design of an experimental amplifier in Section III of the paper are incorrect. In their reply, Poole and Paul, together with P. Gardner, defend their results. >