Shorter Strip Research Articles

Design Simulation and Fabrication of a Dual Band Frequency Reconfigurable Monopole Antenna for Wi-Fi and WiMAX Applications

Nowadays, wireless systems require compact multi band antennas that can dynamically change some of its fundamental parameters such as frequency band, polarization and radiation pattern. The novelty of the proposed work lies in using two conducting strips that are perpendicular to each other. The longer strip resonates at 2.4 GHz and the shorter strip resonates at 3.5 GHz. The length and width of the Ground plane is made equal to length of the main arm and length of the side arm respectively. The results are obtained by simulating the antenna structure using simulation tool Ansoft HFSS v15.0. The Simulated antenna Gains were 6.2364 dBi and 7.1758 dBi for frequencies of 2.4 GHz and 3.5 GHz respectively. The antenna dimensions are 50 × 25 × 1.6 mm3 on a 1.6 mm thick FR-4 substrate.

A Reconfigurable Antenna for LTE/WWAN Mobile Handset Applications

In this letter, a reconfigurable antenna for mobile handset applications is proposed. This antenna mainly consists of a longer strip, a shorter strip, and a p-i-n diode. Coupling is generated at the gap between the longer strip and the shorter strip. Depending on the different states of the p-i-n diode, the degree of coupling between them is controlled, and the fundamental resonant frequency of the proposed antenna is adjusted. As a result, the proposed antenna in the low band covers the LTE700/GSM850/900 bands. The high band is formed by combining higher-order mode of the longer strip and quarter-wavelength mode of the shorter strip to cover the GSM1800/1900/UMTS/LTE2300/2500 bands.

Coupled-fed loop antenna with branch radiators for internal LTE/WWAN laptop computer antenna

A new antenna structure of internal long-term evolution/wireless wide area network (698–960/1710–2690 MHz) laptop computer antenna formed by a coupled-fed loop antenna connected with two branch radiators is presented. The two branch radiators consist of one longer strip and one shorter strip, both being efficient radiators and contributing multiresonant modes to greatly enhance the bandwidth of the antenna. The antenna's lower band is formed by a dual-resonant mode mainly contributed by the longer branch strip, while the upper band is formed by three resonant modes contributed respectively by one higher-order resonant mode of the longer branch strip, one resonant mode of the coupled-fed loop antenna alone, and one resonant mode of the shorter branch strip. The antenna's lower and upper bands can therefore cover the desired 698–960 and 1710–2690 MHz bands, respectively. The proposed antenna is suitable to be mounted at the top shielding metal wall of the display ground of the laptop computer and occupies a small volume of 4 × 10 × 75 mm3 above the top shielding metal wall, which makes it promising to be embedded inside the casing of the laptop computer as an internal antenna. Details of the proposed antenna are studied in the paper. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2662–2667, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25556

Dual band–rejected microstrip antenna for WiMAX/WLAN applications

AbstractIn this article, we propose a novel design to obtain dual band–rejected characteristics in printed microstrip antenna.First, an ultrawide operating band from 2.15 GHz to about 6.50 GHz is achieved by locating the rectangular radiating patch above a larger rectangular notch cut in the finite ground plane edge. Two folded strips with different length protrude from the patch corner with null surface current to introduce dual rejected band. The longer strip and shorter strip are independently associated with lower and upper rejected band. By suitable adjustment in strip lengths, two rejected bands centered at 3 and 4.7 GHz are successfully introduced. Also, a triband operation for 2.5/3.5/5.5 GHz WiMAX and 2.4/5.2/5.8 GHz WLAN applications is achieved for the proposed microstrip antenna. Details of the design considerations are presented, and results of the implemented prototype are discussed. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1901–1905, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25312

Performance Comparison of Rectangular and Air-Foil Shapes Offset Strip Flow Paths Micro-Heat Exchangers

This study designed and tested eight micro-heat exchangers with rectangle-, air-foil-, and shuttle-type strips for use in the liquid cooling system. The effects of strip length, strip type, and strip arrangement were considered for heat transfer performance comparison. The test results show that the heat exchangers with shorter strip length and narrower strip space provide better heat transfer performance. The short air-foil strips heat exchanger with 1.0 mm strip length performed the lowest thermal resistance among all types of heat exchangers. Because of its narrow flow paths, the performance of the overlapped shuttle strip heat exchanger is better than that of the offset shuttle, long air-foil, and rectangle strip heat exchangers. However, the space between strips is limited by the fabrication techniques and is difficult to be made narrower by the method of chemical etching.

Advanced Micro-Heat Exchangers for High Heat Flux

Three micro-heat exchangers for use in a liquid cooling system with a long offset strip, short offset strip, and chevron flow path based on the traditional heat transfer enhancement concepts were designed and tested. A straight channel heat exchanger was also made for comparison. The liquid crystal thermography method described by Lin and Yang (2005) was used to observe the flow and temperature distributions in the micro-heat exchangers. The test results show that the chevron channel heat exchanger provides the lowest thermal resistance. However, its pressure drop is also the highest, approximately five times higher than that for other three heat exchangers. The offset strip heat exchangers provide better thermal performance than does the straight channel heat exchanger. The performance of the heat exchanger with the shorter strip is better than that of heat exchanger with longer strip. From the above results, all of the three micro-heat exchangers with conventional heat transfer enhancement showed less thermal resistance than the straight channel heat exchanger. The conventional heat transfer techniques may be effectively applied in the high-flux micro-heat exchanger design.