scholarly journals Directive Antenna for Ultrawideband Medical Imaging Systems

2008 ◽  
Vol 2008 ◽  
pp. 1-6 ◽  
Author(s):  
Amin M. Abbosh
Keyword(s):  
Human Body ◽  
Time Domain ◽  
Free Space ◽  
Short Pulse ◽  
Imaging Systems ◽  
Backward Radiation ◽  
Directive Antenna ◽  
The Time Domain ◽  
Domain Performance ◽  
Peak Gain

A compact and directive ultrawideband antenna is presented in this paper. The antenna is in the form of an antipodal tapered slot with resistive layers to improve its directivity and to reduce its backward radiation. The antenna operates over the frequency band from 3.1 GHz to more than 10.6 GHz. It features a directive radiation with a peak gain which is between 4 dBi and 11 dBi in the specified band. The time domain performance of the antenna shows negligible distortion. This makes it suitable for the imaging systems which require a very short pulse for transmission/reception. The effect of the multilayer human body on the performance of the antenna is also studied. The breast model is used for this purpose. It is shown that the antenna has more than 90% fidelity factor when it works in free space, whereas the fidelity factor decreases as the signal propagates inside the human body. However, even inside the human body, the fidelity factor is still larger than 70% revealing the possibility of using the proposed antenna in biomedical imaging systems.

scholarly journals Time-domain analysis of distortion-product otoacoustic emissions using a hydrodynamic cochlea model

2017 ◽  
Vol 3 (2) ◽  
pp. 453-456
Author(s):  
Dennis Zelle ◽  
Ernst Dalhoff ◽  
Anthony W. Gummer
Keyword(s):  
Time Domain ◽  
Otoacoustic Emissions ◽  
Short Pulse ◽  
Human Subjects ◽  
Time Domain Analysis ◽  
Distortion Product Otoacoustic Emissions ◽  
Sound Waves ◽  
Cochlear Function ◽  
Distortion Product ◽  
The Time Domain

AbstractAs a by-product of nonlinear amplification in the cochlea, the inner ear emits sound waves in response to two tones with different frequencies. These sound waves are measurable in the ear canal as distortion-product otoacoustic emissions (DPOAEs). DPOAEs putatively consist of two components emerging at different locations in the cochlea. Wave interference between the two components limits the accuracy of DPOAEs as a noninvasive measure of cochlear function. Using short stimulus pulses instead of continuous stimuli, the two DPOAE components can be separated in the time domain due to their different latencies. The present work utilizes a nonlinear hydrodynamic cochlea model to simulate short-pulse DPOAEs in the time domain. When adding irregularities to the mechanical parameters of the model, the simulated DPOAE signals show two distinguishable components and long-lasting beat tones, similar to band-pass filtered experimental data from normal-hearing human subjects. The model results suggest that the beat tones can occur solely due to interference of the coherent-reflection component with the fading nonlinear-distortion component.

scholarly journals Time-Domain Investigation of Switchable Filter Wide-Band Antenna for Microwave Breast Imaging

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4302 ◽  
Author(s):  
Amir Haider ◽  
MuhibUr Rahman ◽  
Mahdi Naghshvarianjahromi ◽  
Hyung Seok Kim
Keyword(s):  
Time Domain ◽  
Breast Imaging ◽  
Wide Band ◽  
Tumor Detection ◽  
Ultra Wideband ◽  
Good Time ◽  
Area Network ◽  
Microwave Breast Imaging ◽  
The Time Domain ◽  
Domain Performance

This paper investigates the time-domain performance of a switchable filter impulse radio ultra-wideband (IR-UWB) antenna for microwave breast imaging applications. A miniaturized CPW-fed integrated filter antenna with switchable performance in the range of the Worldwide Interoperability for Microwave Access (WiMAX) and Wireless Local Area Network (WLAN) bands could operate well within a 3.0 to 11 GHz frequency range. The time-domain performance of the filter antenna was investigated in comparison to that of the designed reference wideband antenna. By comparing both antennas’ time-domain characteristics, it was seen that the switchable filter antenna had good time-domain resolution along with the frequency-domain operation. Additionally, the time-domain investigation revealed that the switchable filter wide-band antenna performed similarly to the reference wide band antenna. This antenna was also utilized for a tumor detection application, and it was seen that the switchable filter wide-band antenna could detect a miniaturized irregularly shaped tumor easily, which is quite promising. Such an antenna with a good time-domain resolution and tumor detection capability will be a good candidate and will find potential applications in microwave breast imaging.

Terahertz quantum optics in the time-domain: from field correlation measurements on vacuum field fluctuations in free space towards cavity electro-optics

2020 ◽  
Author(s):  
Ileana-Cristina Benea-Chelmus ◽  
Francesca Fabiana Settembrini ◽  
Yannick Salamin ◽  
Yuriy Fedoryshyn ◽  
Wolfgang Heni ◽  
...  
Keyword(s):  
Quantum Optics ◽  
Time Domain ◽  
Free Space ◽  
Vacuum Field ◽  
Field Fluctuations ◽  
The Time Domain ◽  
Field Correlation

Measurements of Shielding Effectiveness of Textile Materials Containing Metal by the Free-Space Transmission Technique with Data Processing in the Time Domain

2013 ◽  
Vol 20 (2) ◽  
pp. 217-228 ◽  
Author(s):  
Nadezhda Dvurechenskaya ◽  
Pawe R. Bajurko ◽  
Ryszard J. Zieliński ◽  
Yevhen Yashchyshyn
Keyword(s):  
Data Processing ◽  
Time Domain ◽  
Free Space ◽  
Coaxial Line ◽  
Shielding Effectiveness ◽  
Experimental Data Processing ◽  
Textile Materials ◽  
Transmission Technique ◽  
Set Up ◽  
The Time Domain

Abstract The results of shielding effectiveness (SE) measurements of textile materials containing metal by the free-space transmission technique (FSTT) in the 1-26.5 GHz frequency range are presented in the paper. It is shown that experimental data processing using time-domain gating (TDG) makes it possible to effectively remove diffracted and reflected components from the desired signal. The comparison with the results obtained by other techniques, namely modified FSTT with TDG and coaxial line probe technique (ASTM D4935-99) is given. The comparison shows that the proposed technique gives more reasonable results while the measurement set-up is simpler in realization.

scholarly journals Free-Space Materials Characterization by Reflection and Transmission Measurements using Frequency-by-Frequency and Multi-Frequency Algorithms

Electronics ◽  
2018 ◽  
Vol 7 (10) ◽  
pp. 260 ◽  
Author(s):  
Fábio Gonçalves ◽  
Alfred Pinto ◽  
Renato Mesquita ◽  
Elson Silva ◽  
Adriana Brancaccio
Keyword(s):  
Time Domain ◽  
Free Space ◽  
Dielectric Materials ◽  
Weighting Factor ◽  
Reflection And Transmission ◽  
Favorable Configuration ◽  
The Time Domain ◽  
Transmission And Reflection

The knowledge of the electromagnetic constitutive properties of materials is crucial in many applications. Free-space methods are widely used for this purpose, despite their inherent practical difficulties. This paper describes an affordable free-space experimental setup for the characterization of flat samples in 1–6 GHz in a non-anechoic environment. The extracted properties are obtained from the calibrated Scattering Parameters, using a frequency-by-frequency solution or a multi-frequency reconstruction. For the first, we describe how the Time-Domain Gating can be implemented and used for filtering the signals. For the latter, a weighting factor is introduced to balance the reflection and transmission data, allowing one to have a more favorable configuration. The different role of transmission and reflection measurements on the achievable results is analyzed with regard to experimental uncertainties and different noise scenarios. Results from the two strategies are analyzed and compared. Good agreement between simulation, measurement and literature is obtained. According to the reported results for dielectric materials, there is no need of filtering the data by a Time-Domain Gating in case of the multi-frequency approach. Experimental results for Polymethylmethacrylate (PMMA) and Polytetrafluorethylene (PTFE) samples validate both the setup and the processing.

Time and Frequency Domain Performance Comparison for Wheeze Detection Using K-Nearest Neighbor

2014 ◽  
Vol 591 ◽  
pp. 163-166
Author(s):  
Syamimi Mardiah Shaharum ◽  
Kenneth Sundaraj
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
High Performance ◽  
Nearest Neighbor ◽  
Dominant Frequency ◽  
Performance Comparison ◽  
K Nearest Neighbor ◽  
Time Domain Data ◽  
The Time Domain ◽  
Domain Performance

In this Paper, the Comparison between the Performance of Wheezes Data Processing in the Frequency Domain and in the Time Domain is Evaluated Using K-Nearest Neighbor (KNN). the Purpose of this Paper is to Clarify the Confusion Regarding the Methods Used Nowadays, as many of the Previous Researchers have Stated that Wheezes Data are Better Processed in the Frequency Domain due to its Dominant Frequency Peaks but Not a Single Researcher has Made a Direct Comparison to Prove the Reliability of the Method Used. from the Evaluation Made, the Result Shows that the Performance of Wheeze Data Processed in the Frequency Domain is Better as Compared to the Data Processed in the Time Domain. A High Performance Accuracy with 97% is Obtained Comparing to an Accuracy Percentage of 83.13% were only Achieved by Using the Time Domain Data. Thus, this Paper has Successfully Made a Comparison between the Domains Proving the Reliability of the Frequency Domain for Wheeze Detection.

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