High frequency effect of the junction between cone tip, coaxial feeder and ground plane on the input impedance of a long monocone antenna on ground plane

1995 ◽  
Author(s):  
M. Piette
Keyword(s):  
High Frequency ◽  
Input Impedance ◽  
Ground Plane ◽  
Frequency Effect

scholarly journals Design of a Compact CPW-Fed Monopole Antenna With Asymmetrical Hexagonal Slot Loaded Ground Structure for C/X/Ku Band Applications

2020 ◽  
Vol 16 (1) ◽  
pp. 15-22
Author(s):  
Ajay Kumar Dwivedi ◽  
Brijesh Mishra ◽  
Vivek Singh ◽  
Pramod Narayan Tripathi ◽  
Ashutosh Kumar Singh
Keyword(s):  
High Frequency ◽  
Ground Plane ◽  
Directional Pattern ◽  
Ultra Wideband ◽  
Impedance Bandwidth ◽  
Ground Structure ◽  
High Frequency Structure Simulator ◽  
Performance Matrix ◽  
Novel Design ◽  
Ku Band

AbstractA novel design of ultra-wideband CPW-fed compact monopole patch antenna is presented in the article. The size of the antenna is 22 × 18 × 1.6 mm and it operates well over an ultra-wideband frequency range 4.86–13.66 GHz (simulated) and 4.93–13.54 GHz (measured) covering C, X and partial Ku band applications. The proposed design consists of a defected ground plane and U-shape radiating patch along with two square shape parasitic patches in order to achieve the ultra-wideband (UWB) operations. The performance matrix is validated through measured results that indicate the wide impedance bandwidth (93.2 %) with maximum gain of 4 dBi with nearly 95 % of maximum radiation efficiency; moreover, the 3D gain pattern manifests approximately omni-directional pattern of the proposed design. The prototype has been modelled using HFSS (High Frequency Structure Simulator-18) by ANSYS, fabricated and tested using vector network analyser E5071C.

A method to quantify hand-transmitted vibration exposure based on the biodynamic stress concept

2007 ◽  
Vol 221 (8) ◽  
pp. 847-861 ◽  
Author(s):  
R G Dong ◽  
D E Welcome ◽  
J Z Wu
Keyword(s):  
Experimental Data ◽  
High Frequency ◽  
Practical Method ◽  
The Other ◽  
Equivalent Model ◽  
Frequency Effect ◽  
Vibration Exposure ◽  
Stress Cycle ◽  
Vibration Induced White Finger ◽  
Frequency Weightings

This study generally hypothesized that the vibration-induced biodynamic stress and number of its cycles in a substructure of the hand-arm system play an important role in the development of vibration-induced disorders in the substructure. As the first step to test this hypothesis, the specific aims of this study were to develop a practical method to quantify the biodynamic stress-cycle measure, to compare it with ISO-weighted and unweighted accelerations, and to assess its potential for applications. A mechanical-equivalent model of the system was established using reported experimental data. The model was used to estimate the average stresses in the fingers and palm. The frequency weightings of the stresses in these substructures were derived using the proposed stress-cycle measure. This study found the frequency dependence of the average stress distributed in the fingers is different from that in the palm. Therefore, this study predicted that the frequency dependencies of finger disorders could also be different from those of the disorders in the palm, wrist, and arms. If vibration-induced white finger (VWF) is correlated better with unweighted acceleration than with ISO-weighted acceleration, the biodynamic stress distributed in the fingers is likely to play a more important role in the development of VWF than is the biodynamic stress distributed in the other substructures of the hand-arm system. The results of this study also suggest that the ISO weighting underestimates the high-frequency effect on the finger disorder development but it may provide a reasonable risk assessment of the disorders in the wrist and arm.

Nonword repetition and levels of abstraction in phonological knowledge

2006 ◽  
Vol 27 (4) ◽  
pp. 577-581 ◽  
Author(s):  
Benjamin Munson
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Nonword Repetition ◽  
Chronological Age ◽  
Frequency Effect ◽  
Vocabulary Size ◽  
Levels Of Abstraction ◽  
Opposite Pattern ◽  
The Difference ◽  
Restriction Of Range

Susan Gathercole's Keynote Article (2006) is an impressive summary of the literature on nonword repetition and its relationship to word learning and vocabulary size. When considering research by Mary Beckman, Jan Edwards, and myself, Gathercole speculates that our finding of a stronger relationship between vocabulary measures and repetition accuracy for low-frequency sequences than for high-frequency sequences is due to differences in the range of the two measures. In our work on diphone repetition (e.g., Edwards, Beckman, & Munson, 2004; Munson, Edwards, & Beckman, 2005) we tried to increase the range in our dependent measures by coding errors on a finer grained scale than simple correct/incorrect scoring would allow. Moreover, restriction of range does not appear to be the driving factor in the relationship between vocabulary size and the difference between high- and low-frequency sequence repetition accuracy (what we call the frequency effect) in at least one of our studies (Munson et al., 2005). When the children with the 50 lowest mean accuracy scores for high-frequency sequences were examined, vocabulary size accounted for 10.5% of the variance in the frequency effect beyond what was accounted for by chronological age. When the 50 children with the highest mean accuracy scores for high-frequency sequences were examined (a group in which the range of high-frequency accuracy scores was more compressed, arguably reflecting ceiling effects), an estimate of vocabulary size accounted for only 6.9% of the frequency effect beyond chronological age. The associated β coefficient was significant only at the α<0.08 level. This is the opposite pattern than Gathercole's argument would predict.

Development of a New Fatigue Testing Machine for High Frequency Fatigue Damage Assessment

2013 ◽  
Author(s):  
Naoki Osawa ◽  
Tetsuya Nakamura ◽  
Norio Yamamoto ◽  
Junji Sawamura
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Fatigue Testing ◽  
Low Cost ◽  
Plate Thickness ◽  
Testing Machine ◽  
Fatigue Tests ◽  
Frequency Effect ◽  
Wave Load ◽  
Out Of Plane

A new simple fatigue testing machine, which can carry out fast and low-cost fatigue tests of welded joints subject to wave with high frequency vibration, has been developed. This machine is designed for plate bending type fatigue tests, and wave load is applied by using motors with eccentric mass. Springing vibration is superimposed by attaching an additional vibrator to the test specimen, and whipping vibration is superimposed by an intermittent hammering. Fatigue tests which simulate springing and whipping by a conventional servo-type fatigue testing machines are very expensive and use a large amount of electricity. If one uses these conventional machines, it is difficult to simulate superimposed stress wave forms at high speed, and it takes long hours of testing to examine the high frequency effect. In contrast, it is found that fatigue tests can be carried out in fast, i.e. waves with 10Hz or higher frequency for out-of-plane gusset welded joint specimens with 12mm plate thickness by using the developed machine. The electricity to be used for fatigue tests could be minimal, for example one thousandth of that needed for conventional machines. These results demonstrate the superiority of the developed machine.

Measurement of IGBT High-Frequency Input Impedance in Short Circuit

2017 ◽  
Vol 32 (1) ◽  
pp. 584-592 ◽  
Author(s):  
Carmine Abbate ◽  
Giovanni Busatto ◽  
Annunziata Sanseverino ◽  
Francesco Velardi ◽  
Sara Iavarone ◽  
...  
Keyword(s):  
High Frequency ◽  
Input Impedance ◽  
Short Circuit

scholarly journals Evaluation of Cerebrovascular Impedance and Wave Reflection in Mouse by Ultrasound

2015 ◽  
Vol 35 (3) ◽  
pp. 521-526 ◽  
Author(s):  
Christopher K Macgowan ◽  
Sarah Joy Stoops ◽  
Yu-Qing Zhou ◽  
Lindsay S Cahill ◽  
John G Sled
Keyword(s):  
Blood Flow ◽  
Carotid Artery ◽  
High Frequency ◽  
Input Impedance ◽  
Wave Reflection ◽  
Arterial Compliance ◽  
High Frequency Ultrasound ◽  
Microvascular Changes ◽  
Total Arterial Compliance ◽  
Frequency Ultrasound

Genetic and surgical mouse models are commonly used to study cerebrovascular disease, but their size makes invasive hemodynamic testing technically challenging. The purpose of this study was to demonstrate a noninvasive measurement of cerebrovascular impedance and wave reflection in mice using high-frequency ultrasound in the left common carotid artery (LCCA), and to examine whether microvascular changes associated with hypercapnia could be detected with such an approach. Ten mice (C57BL/6J) were studied using a high-frequency ultrasound system (40 MHz). Lumen area and blood flow waveforms were obtained from the LCCA and used to calculate pulse-wave velocity, input impedance, and reflection amplitude and transit time under both normocapnic and hypercapnic (5% CO2) ventilation. With hypercapnia, vascular resistance was observed to decrease by 87%±12%. Although the modulus of input impedance was unchanged with hypercapnia, a phase decrease indicative of increased total arterial compliance was observed at low harmonics together with an increased reflection coefficient in both the time (0.57±0.08 versus 0.68±0.08, P=0.04) and frequency domains (0.62±0.08 versus 0.73±0.06, P=0.02). Interestingly, the majority of LCCA blood flow was found to pass into the internal carotid artery (range=76% to 90%, N=3), suggesting that hemodynamic measurements in this vessel are a good metric for intracerebral reactivity in mouse.

A Design of Printed Inverted-F Antenna for RFID Tag at 5.8 GHz

2013 ◽  
Vol 427-429 ◽  
pp. 1293-1296
Author(s):  
Yan Zhong Yu ◽  
Ji Zhen Ni ◽  
Xian Hui Li
Keyword(s):  
High Frequency ◽  
Printed Circuit Board ◽  
Ground Plane ◽  
Simulation Software ◽  
Circuit Board ◽  
Electromagnetic Simulation ◽  
Antenna Structure ◽  
Rfid Tag ◽  
Printed Circuit ◽  
Substrate Layer

A printed inverted-F antenna for RFID tag at 5.8 GHz is designed in this paper. The antenna structure consists of an inverted-F patch, a substrate layer, and a ground plane. To reduce costs, the FR4 is selected as the material of substrate layer, which is used commonly in PCB (Printed Circuit Board). Its relative permittivity is 4.4 and a loss tangent is 0.02. The inverted-F patch and ground plane are laid on/under the substrate layer respectively. The designed antenna is modeled, simulated and optimized by using HFSS (high frequency electromagnetic simulation software). Simulation results demonstrate that the printed inverted-F antenna can satisfy the requirements of RFID Tag applications.

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