Designing reverberation chambers for measurements of small antennas and wireless terminals: Accuracy, frequency resolution, lowest frequency of operation, loading and shielding of chamber

The classical two-channel push-pull chirp transform spectrometer (CTS) has been widely applied in satellite-borne remote sensing systems for earth observation and deep space exploration. In this paper, we present two simplified structures with single M(l)-C(s) CTS arrangements for the spectral analysis of stationary signals. A simplified CTS system with a single M(l)-C(s) arrangement and a time delay line was firstly developed. Another simplified structure of CTS with a M(l)-C(s) arrangement and a frequency conversion channel was also developed for spectral analysis of stationary signals. Simulation and experiment results demonstrate that the two simplified arrangements can both realize spectrum measurement for the stationary signals and obtain the same frequency resolution, amplitude accuracy and system sensitivity as that of the classical two-channel push–pull CTS system. Compared to the classical CTS structure, the two simplified arrangements require fewer devices, save power consumption and have reduced mass. The matching problem between the two channels can be avoided in the two simplified arrangements. The simplified CTS arrangements may have potential application in the spectrum measurement of stationary signals in the field of aviation and spaceflight.

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Parametric Enhancement of Radiation from Electrically Small Antennas

Physical Review Applied ◽

10.1103/physrevapplied.15.054063 ◽

2021 ◽

Vol 15 (5) ◽

Author(s):

Ahmed Mekawy ◽

Huanan Li ◽

Younes Radi ◽

Andrea Alù

Keyword(s):

Electrically Small Antennas ◽

Small Antennas

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Uncorrelated configurations and field uniformity in reverberation chambers stirred by reconfigurable metasurfaces

Applied Physics Letters ◽

10.1063/5.0041837 ◽

2021 ◽

Vol 118 (14) ◽

pp. 144101

Author(s):

J.-B. Gros ◽

G. Lerosey ◽

F. Mortessagne ◽

U. Kuhl ◽

O. Legrand

Keyword(s):

Field Uniformity ◽

Reverberation Chambers

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Evaluation of working memory in relation to cochlear implant consonant speech discrimination

The Egyptian Journal of Otolaryngology ◽

10.1186/s43163-021-00078-w ◽

2021 ◽

Vol 37 (1) ◽

Author(s):

Mai M. El Ghazaly ◽

Mona I. Mourad ◽

Nesrine H. Hamouda ◽

Mohamed A. Talaat

Keyword(s):

Working Memory ◽

Speech Perception ◽

High Frequency ◽

Word List ◽

Frequency Discrimination ◽

Frequency Resolution ◽

Speech Discrimination ◽

Place Of Articulation ◽

Strong Positive Relationship ◽

Speech And Language Development

Abstract Background Speech perception in cochlear implants (CI) is affected by frequency resolution, exposure time, and working memory. Frequency discrimination is especially difficult in CI. Working memory is important for speech and language development and is expected to contribute to the vast variability in CI speech reception and expression outcome. The aim of this study is to evaluate CI patients’ consonants discrimination that varies in voicing, manner, and place of articulation imparting differences in pitch, time, and intensity, and also to evaluate working memory status and its possible effect on consonant discrimination. Results Fifty-five CI patients were included in this study. Their aided thresholds were less than 40 dBHL. Consonant speech discrimination was assessed using Arabic consonant discrimination words. Working memory was assessed using Test of Memory and Learning-2 (TOMAL-2). Subjects were divided according to the onset of hearing loss into prelingual children and postlingual adults and teenagers. Consonant classes studied were fricatives, stops, nasals, and laterals. Performance on the high frequency CVC words was 64.23% ± 17.41 for prelinguals and 61.70% ± 14.47 for postlinguals. These scores were significantly lower than scores on phonetically balanced word list (PBWL) of 79.94% ± 12.69 for prelinguals and 80.80% ± 11.36 for postlinguals. The lowest scores were for the fricatives. Working memory scores were strongly and positively correlated with speech discrimination scores. Conclusions Consonant discrimination using high frequency weighted words can provide a realistic tool for assessment of CI speech perception. Working memory skills showed a strong positive relationship with speech discrimination abilities in CI.

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