scholarly journals Electrically small dual-band substrate-integrated-waveguide antenna with fixed low-frequency and tunable high-frequency bands

2014 ◽  
Vol 11 (5) ◽  
pp. 20140007-20140007 ◽  
Author(s):  
Hyunseong Kang ◽  
Sungjoon Lim
2015 ◽  
Vol 9 (2) ◽  
pp. 447-452 ◽  
Author(s):  
Xi-Wang Dai ◽  
Tao Zhou ◽  
Bo-Ran Guan

A novel dual-band planar antenna with a low profile for mobile communication system is proposed in this paper. The antenna is composed of one shorted patch with two radiating notches for low frequency resonance and one square patch for high frequency resonance. The low profile is achieved via the shorting patch, which introduces the parallel electrical field between the reflector and antenna. A step-impedance microstrip line is used to feed the antenna. The coupling between the square patch and microstrip line cancels out the inductance of shorting probe, which increases the working bandwidth of proposed antenna. A prototype with a low profile of 0.0286λ is fabricated and measured. The antenna achieves dual impedance bandwidths of 1.6% for the low frequency band and 60% for the high frequency band, covering the frequency range 851–865 MHz and 1.97–3.65 GHz, respectively. The measured results show good agreements with the simulated ones.


2011 ◽  
Vol 204-210 ◽  
pp. 1419-1422 ◽  
Author(s):  
Yong Yang

Image fusion is to combine several different source images to form a new image by using a certain method. Recent studies show that among a variety of image fusion algorithms, the wavelet-based method is more effective. In the wavelet-based method, the key technique is the fusion scheme, which can decide the final fused result. This paper presents a novel fusion scheme that integrates the wavelet decomposed coefficients in a quite separate way when fusing images. The method is formed by considering the different physical meanings of the coefficients in both the low frequency and high frequency bands. The fused results were compared with several existing fusion methods and evaluated by three measures of performance. The experimental results can demonstrate that the proposed method can achieve better performance than conventional image fusion methods.


2005 ◽  
Vol 12 (4) ◽  
pp. 237-254
Author(s):  
Yoshihito Kobayashi ◽  
Toshiya Kitamura ◽  
Shinji Yamada

Moulded chairs have been developed, in which sound absorption at low frequency bands is increased by using the seat section and/or the back section as a resonator. In addition, a translucent sound absorption panel has been developed for application in large spaces. In the case of the chairs the resonance frequency, determined by the position, number, and depth of the holes, was examined. Prototypes were constructed, and the equivalent absorption area was measured in a reverberation room. The resonators of the chairs achieved an equivalent absorption area of 0.15 m2/seat, in the 125 Hz band. For the case of the translucent material, sound absorption was measured and compared with conventional sound absorption materials. The panels were designed in order to control sound fields in large spaces. The panels achieved a sound absorption coefficient of 0.6 to 1.0 at middle and high frequency bands.


2011 ◽  
Vol 217-218 ◽  
pp. 311-316 ◽  
Author(s):  
Ying Zhang ◽  
Di Jiang Wen

The RE/Mn co-doped Co-Zn ferrites were prepared by the ceramic method. Infrared absorption and emission properties were obtained by investigating those ferrites. The IR spectra in the range from 400 to 1200 cm-1 were observed. Mainly, three bands were investigated. The high-frequency bands and low-frequency bands were assigned to the tetrahedral and octahedral complexes, respectively. The intensity of all the bands is found to increase while a decrease in broadness, which is explained on the cation distribution in the tetrahedral and octahedral sites were modified by RE/Mn addition. The Mn substitutes the Fe3+ and enters into the octahedral sites; while the partial RE3+ ions are apt to diffuse to the grain boundaries and others enter into the spinel lattice .This can be explained on the basis of ionic radii and ratios of the substituted cation. The results indicate that IR emissivity seems to be increasing with RE/Mn ratio within 8-14 μm wavebands. The maximum infrared emissivity is 0.968 when La/Mn ratio of 0.20 within 8-14 μm wavebands.


Author(s):  
GAURAV BHATNAGAR ◽  
Q. M. JONATHAN WU

In this paper, a novel image fusion algorithm based on framelet transform is presented. The core idea is to decompose all the images to be fused into low and high-frequency bands using framelet transform. For fusion, two different selection strategies are developed and used for low and high-frequency bands. The first strategy is adaptive weighted average based on local energy and is applied to fuse the low-frequency bands. In order to fuse high-frequency bands, a new strategy is developed based on texture while exploiting the human visual system characteristics, which can preserve more details in source images and further improve the quality of fused image. Experimental results demonstrate the efficiency and better performance than existing image fusion methods both in visual inspection and objective evaluation criteria.


2017 ◽  
Vol 7 (1.1) ◽  
pp. 631
Author(s):  
Sravya Velaga ◽  
Jagadeesh Korrapati ◽  
Chaithanya Krishna B ◽  
Vandana Matti ◽  
K Ch. Sri Kavya ◽  
...  

The objective of this study was to perform a spectral analysis of the Ka band propagation channel. Now a day, because of the expanding interest of the end users for multimedia services which require vast bandwidth, and because of the immersion of low frequency bands, for example, L, S, C bands, and Ku band in close future, satellite media transmission systems are moving to higher frequency bands. In such high frequency bands, the presence of the atmosphere strongly affects radiowave propagation and attenuation effects become so severe that system availability would not be sufficient if systems were designed in a conventional way with a static propagation margin. 


Author(s):  
Mummadi Gowthami Reddy ◽  
Palagiri Veera Narayana Reddy ◽  
Patil Ramana Reddy

In the current era of technological development, medical imaging plays an important role in many applications of medical diagnosis and therapy. In this regard, medical image fusion could be a powerful tool to combine multi-modal images by using image processing techniques. But, conventional approaches failed to provide the effective image quality assessments and robustness of fused image. To overcome these drawbacks, in this work three-stage multiscale decomposition (TSMSD) using pulse-coupled neural networks with adaptive arguments (PCNN-AA) approach is proposed for multi-modal medical image fusion. Initially, nonsubsampled shearlet transform (NSST) is applied onto the source images to decompose them into low frequency and high frequency bands. Then, low frequency bands of both the source images are fused using nonlinear anisotropic filtering with discrete Karhunen–Loeve transform (NLAF-DKLT) methodology. Next, high frequency bands obtained from NSST are fused using PCNN-AA approach. Now, fused low frequency and high frequency bands are reconstructed using NSST reconstruction. Finally, band fusion rule algorithm with pyramid reconstruction is applied to get final fused medical image. Extensive simulation outcome discloses the superiority of proposed TSMSD using PCNN-AA approach as compared to state-of-the-art medical image fusion methods in terms of fusion quality metrics such as entropy (E), mutual information (MI), mean (M), standard deviation (STD), correlation coefficient (CC) and computational complexity.


2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Haixia Liu ◽  
Bo Lu ◽  
Long Li

A novel octaband LTE mobile phone antenna is presented, which has a compact size with the overall dimension of 35 mm × 9 mm × 3 mm. The miniaturized octaband antenna is implemented by a simple prototype of three parts which include a folded monopole as feeding element, main radiator element, and parasitic radiator element. The main and parasitic radiator elements are excited by the folded monopole feeding element coupling and shorting to the handset ground plane. A wide bandwidth in low-frequency bands covering from 747 MHz to 960 MHz (LTE Band13/GSM850/GSM900) is contributed by both main and parasitic radiator elements. In addition, the folded monopole is designed to resonate at 2530 MHz, and the coupling between the feeding element and main radiator element is designed to resonate at 1840 MHz. Subsequently, the wide bandwidth in high-frequency bands covering from 1710 MHz to 2690 MHz (DCS1800/PCS1900/WCDMA2100/LTE2300/LTE2500) is contributed by both structures. The antenna has the total efficiency up to 30% in low bands and up to 75% in high bands, respectively. At the same time, the proposed miniaturized octaband LTE mobile phone antenna is fabricated and tested to verify the design.


2014 ◽  
Vol 57 (5) ◽  
pp. 2024-2030 ◽  
Author(s):  
In-Ki Jin ◽  
James M. Kates ◽  
Kathryn H. Arehart

Purpose The purpose of this study was to identify whether differences in dynamic range (DR) are evident across the spoken languages of Korean, English, and Mandarin. Method Recorded sentence-level speech materials were used as stimuli. DR was quantified using different definitions of DR (defined as the range in decibels from the highest to the lowest signal intensities), for several integration times (from 1 to 512 ms) and in different frequency bands (center frequencies [CFs] ranging from 150 to 8600 Hz). Results Across the 3 languages, DR was affected in similar ways with regard to changes in DR definition and integration time. In contrast, across-language differences in DR were evident when considering frequency-band effects. Specifically, the DR for Korean was smaller than the English DR and the Mandarin DR in low-frequency bands (less than the CF of 455 Hz). Compared with Korean and Mandarin, the DR for English was smallest in mid-frequency bands (between the CF of 455 Hz and 4050 Hz) and was greatest in high-frequency bands (above the CF of 4050 Hz). Conclusion The observed differences in DR across languages suggest that the best-fit DR for Korean and Mandarin may be different than the best fit for English.


2011 ◽  
Vol 114 (3) ◽  
pp. 588-595 ◽  
Author(s):  
Anthony G. Hudetz ◽  
Jeannette A. Vizuete ◽  
Siveshigan Pillay

Background Cortical γ oscillations are thought to play a role in conscious cognitive functions. Suppression of 40-Hz γ activity was implicated in the loss of consciousness during general anesthesia. However, several experimental studies found that γ oscillations were preserved in anesthesia. The authors investigated the concentration-dependent effect of isoflurane on spontaneous γ oscillations in two frequency bands and three distinct brain regions in the rat. Methods Adult Sprague-Dawley rats were chronically implanted with epidural and coaxial depth electrodes to record cortical field potentials in frontal cortex, visual cortex, and hippocampus in waking and at steady-state isoflurane concentrations of 0.4, 0.8, and 1.2%. The γ power was calculated for the frequency bands 30-50 and 70-140 Hz. Temporal variation and interregional synchrony of γ activity were analyzed using wavelet transform. Loss of consciousness was indexed by the loss of righting reflex. Results Rats lost their righting reflex at 0.8 ± 0.1% isoflurane. High-frequency γ power was decreased by isoflurane in a concentration-dependent manner (P < 0.001, 50% decrease at 0.8% isoflurane) in all brain regions. Low-frequency γ power was unaffected by isoflurane. The duration and interregional synchrony of high-frequency γ bursts was also reduced (P l < 0.001, 40% decrease at 0.8% isoflurane). Conclusions Distinction between high- and low-frequency γ bands is important when evaluating the effect of general anesthetics on brain electrical activity. Spontaneous 40-Hz γ power does not indicate the state of consciousness. The attenuation and interregional desynchronization of high-frequency γ oscillations appear to correlate with the loss of consciousness.


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