Stepped Impedance Resonator Structure Research Articles

Flexible Wearable Composite Antennas for Global Wireless Communication Systems.

Although wearable antennas have made great progress in recent years, how to design high-performance antennas suitable for most wireless communication systems has always been the direction of RF workers. In this paper, a new approach for the design and manufacture of a compact, low-profile, broadband, omni-directional and conformal antenna is presented, including the use of a customized flexible dielectric substrate with high permittivity and low loss tangent to realize the compact sensing antenna. Poly-di-methyl-siloxane (PDMS) is doped a certain proportion of aluminum trioxide (Al2O3) and Poly-tetra-fluoro-ethylene (PTFE) to investigate the effect of dielectric constant and loss tangent. Through a large number of comparative experiments, data on different doping ratios show that the new doped materials are flexible enough to increase dielectric constant, reduce loss tangent and significantly improve the load resistance capacity. The antenna is configured with a multisection microstrip stepped impedance resonator structure (SIR) to expand the bandwidth. The measured reflection return loss (S11) showed an operating frequency band from 0.99 to 9.41 GHz, with a band ratio of 146%. The antenna covers two important frequency bands, 1.71–2.484 GHz (personal communication system and wireless body area network (WBAN) systems) and 5.15–5.825 GHz (wireless local area network-WLAN)]. It also passed the SAR test for human safety. Therefore, the proposed antenna offers a good chance for full coverage of WLAN and large-scale development of wearable products. It also has potential applications in communication systems, wireless energy acquisition systems and other wireless systems.

3-D Absorptive Energy-Selective Structures

In this article, an absorptive energy-selective structure (ESS) based on a 3-D structure mounted with p-i-n limiter diodes is proposed for achieving high-power electromagnetic protection and low reflection at the same time. Two separate transmission and absorption paths are constructed by the 3-D structure. They are activated and bypassed, respectively, under a low-power incidence with turned-off diodes generating a high-efficiency transmission window and out-of-band absorption. On the contrary, the diodes are turned on and the structure is then short-circuited under a high-power incidence, leading to high shielding effectiveness and low reflection. To demonstrate the design concept, an absorptive ESS operating at 3 GHz is designed. Cuboid absorbing material with high power-handling capacity is employed to absorb the undesired incident signals. A stepped-impedance resonator structure is constructed as the transmission path to reduce the profile of the 3-D structure. Equivalent circuit models are derived to explain the operating principle and to deduce the design guidelines. Furthermore, the absorptive ESS is fabricated and tested achieving a good agreement between simulated and measured results. High-efficiency transmission with |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> | > -0.7 dB under the low-power incidence, high shielding effectiveness with |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> | <; -40 dB under the high-power incidence, and low reflection with |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | <; -10 dB are achieved at the operating frequency.

AN ANALYSIS OF HIGH SELECTIVITY AND HARMONIC SUPPRESSION BASED ON STEPPED-IMPEDANCE RESONATOR STRUCTURE FOR DUAL-MODE DIPLEXER

AN ANALYSIS OF HIGH SELECTIVITY AND HARMONIC SUPPRESSION BASED ON STEPPED-IMPEDANCE RESONATOR STRUCTURE FOR DUAL-MODE DIPLEXER

Compact low‐loss microstrip diplexer for RF energy harvesting

A compact low-loss microstrip diplexer that forms by two band-stop filters using interdigital capacitor and a stepped-impedance resonator structure when joined by a miniature T-junction is introduced. The diplexer operates at global system for mobile communication frequency 1800 MHz and 2.45 GHz WLAN frequency which are the most available frequency bands for RF energy harvesting applications. Simulated and measured results are in very good agreement with low insertion loss of 0.4 dB and high selectivity characteristics.

Develop compact dual‐band bandpass filters on the aluminum oxide

AbstractFor the purpose of minimizing the dual‐band bandpass filters (2.4 and 5.7 GHz), two stepped impedance resonator structures are modified and involved in a pair of distorted coupled lines to form a compact structure.And because the designed filter is printed on the high quality factor and dielectric constant aluminum oxide ceramic substrate by the screen‐printing technique, the characteristics of the filters could be improved and the size of the filters could be minimized to only 22.2 × 12 mm2. Furthermore, the modified SIR structure can be used to tune the second resonant frequency (harmonic) for the applications of dual bands, and the modified coupled line structures can be used to excite additional transmission zeros and adjust its locations, which can improve the characteristics of the filters effectively. In this article, the optimum measured insertion loss and bandwidth for 2.4 GHz are −0.98 dB and 11.1%, respectively, and for 5.7 GHz are −1.05 dB and 10.1%, respectively. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1091–1094, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25126