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<p><b>A Comprehensive Review of the Recent Advances in Anechoic Chamber and Reverberation Chamber Designs and Measurements</b></p> <p><i>Anechoic and Reverberation Chambers</i> is a guide to the latest systematic solutions for designing anechoic chambers that rely on state-of-the-art computational electromagnetic algorithms. This essential resource contains a theoretical and practical understanding for electromagnetic compatibility and antenna testing. The solutions outlined optimise chamber performance in the structure, absorber layout and antenna positions whilst minimising the overall cost. The anechoic chamber designs are verified by measurement results from Microwave Vision Group that validate the accuracy of the solution.</p> <p><i>Anechoic and Reverberation Chambers</i> fills an important gap in the literature by providing a comprehensive reference to electromagnetic measurements, applications and over-the-air tests inside chambers. The expert contributors offer a summary of the latest developments in anechoic and reverberation chambers to help scientists and engineers apply the most recent technologies in the field. In addition, the book contains a comparison between reverberation and anechoic chambers and identifies their strengths and weaknesses. This important resource:</p> <ul> <li>Provides a systematic solution for anechoic chamber design by using state-of-the-art computational electromagnetic algorithms</li> <li>Examines both types of chamber in use, comparing and contrasting the advantages and disadvantages of each</li> <li>Reviews typical over-the-air measurements and new applications in reverberation chambers</li> <li>Offers a timely and complete reference written by authors working at the cutting edge of the technology</li> <li>Contains helpful illustrations, photographs, practical examples and comparisons between measurements and simulations</li> </ul> <p>Written for both academics and industrial engineers and designers, <i>Anechoic and Reverberation Chambers</i> explores the most recent advances in anechoic chamber and reverberation chamber designs and measurements.</p>

In this article, we study the characteristics of reverberation interference that occurs in a marine environment when long tonal pulses are emmited and scattered signals are recorded using the so-called bistatic scheme, i.e., when the receiver is located a large distance from the transducer. Probing of the water area with tonal pulses is carried out with the necessary resolution to study both the Doppler spectrum, and temporal development of the reverberation signal is achieved by selecting the proper pulse length. The presented theoretical model is applicable to both the direct and inverse problems, which are forecasting the characteristics of reverberation for a given sea state and determining the properties of the marine environment, mainly its near-surface layer, based on the results of acoustic sounding. The model represents a scattered signal as the superposition of reflections from scatterers, which are distributed along the depth and move along circular trajectories. Their speeds are determined by the maximum amplitude and period of wind waves. The article continues a series of studies and generalizes the previous results to the conditions of significantly spatially offset sound sources and receivers. The modeling results are confirmed by experimental data, involving such parameters as the width of the Doppler spectrum and law of decay of reverberation intensity over time.

Field uniformity is one of the most important parameters for evaluating the uncertainty of electromagnetic reverberation chambers. In this paper, the field uniformity is divided into intrinsic and tuning sample component, and an assumption is proposed to clarify the relationship between the total field uniformity and two decomposed components. Standardized field uniformity is conducted in experiment. Then experimental results indicate that the intrinsic component is related to the design and change with frequency, while the tuning sample uncertainty component is related to the number of stirring paddles and independent of frequency.

The statistical properties of the reverberation chamber (RC) provide a theoretical basis for over-the-air (OTA) testing of wireless devices. This paper analyses the effect of different tuner steps on OTA testing by constructing an RC-based OTA test system. The test results show that the mean value of the total radiated power (TRP) gradually converges as the number of tuner steps increases. However, due to the limited number of independent samples provided by the tuner, the measurement accuracy cannot be improved infinitely by just increasing the number of tuner steps. The number of independent samples for one rotation of the tuner at 2437MHz is also calculated.

The article presents the results of comparative studies concerning the efficiency of systems aimed at minimising the acoustic nuisance of noise generated by the railway vehicle movement. The issue of noise in railway traffic is a significant challenge, affecting both human health and the quality of life in the vicinity of railway lines. Prototype sound absorbing panels with varied surface geometry, a rubber slab, and ballast layer (stone aggregate, grain size 31.5/50mm) were examined. Experiments were conducted in a reverberation chamber, analysing the response to broadband noise excitation. The reverberation chamber allows for obtaining repeatable results, eliminating the influence of external sound sources. It enables the assessment of the sound absorption properties of various materials which makes it possible to determine their effectiveness in noise reduction. The research methodology included measurements of reverberation time in different frequency bands for an empty chamber and a chamber containing the tested materials. The obtained differences in reverberation times provide information on the influence of the tested material on the distribution of acoustic energy in individual frequency bands. The research results allow for a preliminary assessment of the effectiveness of the tested materials in the task of reducing railway line noise.

The detection performance of active sonar is often hindered by the presence of seabed reverberation in shallow water. Separating the reverberations from the target echo and noise in the received signal is a crucial challenge in the field of underwater acoustic signal processing. To address this issue, an improved Go-SOR decomposition method is proposed based on the subspace-orbit-randomized singular value decomposition (SOR-SVD). This method successfully extracts the low-rank structure with a certain striation pattern. The results demonstrate that the proposed algorithm outperforms both the original Go algorithm and the current state-of-the-art (SOTA) algorithm in terms of the definition index of the low-rank structure and computational efficiency. Based on the monostatic reverberation theory of the normal mode, it is established that the low-rank structure is consistent with the low-frequency reverberation interference striation. This study examines the interference characteristics of the low-rank structure in the experimental sea area and suggests that the interferences of the fifth and seventh modes mainly control the low-rank structure. The findings of this study can be applied to seafloor exploration, reverberation waveguide invariant (RWI) extraction, and data-driven reverberation suppression methods.

In environments with a low signal-to-reverberation ratio (SRR) characterized by fluctuations in clutter number and distribution, particle filter-based tracking methods may experience significant fluctuations in the posterior probability of existence. This can lead to interruptions or even loss of the target trajectory. To address this issue, an adaptive PF-based tracking method (APF) with joint reverberation suppression is proposed. This method establishes the state space model under the Bayesian framework and implements it through particle filtering. To keep the weak target echoes, all the non-zero entries contained in the sparse matrix processed by the low-rank and sparsity decomposition (LRSD) are treated as the measurements. The prominent feature of this approach is introducing an adaptive measurement likelihood ratio (AMLR) into the posterior update step, which solves the problem of unstable tracking due to the strong fluctuation in the number of point measurements per frame. The proposed method is verified by four shallow water experimental datasets obtained by an active sonar with a uniform horizontal linear array. The results demonstrate that the tracking frame success ratio of the proposed method improved by over 14% compared with the conventional PF tracking method.

This paper introduces two deep learning approaches to localize acoustic emissions (AE) sources within metallic plates with geometric features, such as rivet-connected stiffeners. In particular, a stack of autoencoders and a convolutional neural network are used. The idea is to leverage the reflection and reverberation patterns of AE waveforms as well as their dispersive and multimodal characteristics to localize their sources with only one sensor. Specifically, this paper divides the structure into multiple zones and finds the zone in which each source occurs. To train, validate, and test the deep learning networks, fatigue cracks were experimentally simulated by Hsu–Nielsen pencil lead break tests. The pencil lead breaks were carried out on the surface and at the edges of the plate. The results show that both deep learning networks can learn to map AE signals to their sources. These results demonstrate that the reverberation patterns of AE sources contain pertinent information to the location of their sources.

P‐waves generated by subduction earthquakes can get trapped within the submarine trench, where they reverberate and contaminate the initial seismic signals. We analyze the behavior of P‐wave reverberations for 43 earthquakes of magnitude larger than 6.0 that occurred along the Chilean margin between 1995 and 2023. We compared the energy of the P‐waves versus the Pcoda wave reverberations in order to estimate the proximity of the rupture to the trench. Additionally, we compared their spectra with the oscillation frequency of the water column and generate back‐projection images to locate the source of the reverberations. Our results show that P‐wave reverberations are generated when P‐waves become trapped in the water column formed in the trench, in front of the epicenter, regardless of the proximity of the rupture to the trench.

The acoustic environment of karst tourist caves significantly impacts visitor experience and the effectiveness of information dissemination, yet systematic studies on their acoustics remain scarce. This study investigates the acoustic properties of a representative karst tourist cave in Guizhou Province, China, by combining in-situ measurements with 3D laser scanning. Impulse responses were systematically recorded at 22 positions across six caverns, and key parameters—including reverberation time (T 20 ), early decay time (EDT), definition (D 50 ), clarity (C 80 ), and speech transmission index (STI)—were analyzed in relation to spatial geometries obtained from 3D scans. The results reveal substantial spatial variations in acoustic conditions: mid-frequency T 20 ranges from 1.4 s to 3.1 s, largely governed by cavern volume, geometry, and entrance-related attenuation. The average EDT/T 20 ratio is 0.70, indicating non-uniform early decay behavior. While D 50 values are relatively consistent (0.49–0.74), C 80 shows greater variability (1.86–6.89 dB), both influenced by spatial complexity. Furthermore, significant correlations exist between STI and other parameters ( P  < 0.01), confirming that reverberation control and early-energy enhancement are crucial for improving speech intelligibility. These findings provide a scientific basis for acoustic optimization in show caves, supporting better guided tours and safety communications.