Frequency Band Research Articles

Absorption of 5G sub-6 GHz electromagnetic radiation from base station to male reproduction system

Background The impact of electromagnetic radiation from communication on the male reproductive system has emerged as a significant concern in public health. A notable distinction of the 5G sub-6 GHz band, compared to traditional 2G, 3G, and 4G frequency bands, is the inclusion of higher frequency bands. This has raised public concerns regarding the potential effects of these higher frequencies on organisms, particularly their reproductive systems. While it is imperative to investigate the biological effects and potential risks associated with these new frequency bands in laboratory settings, comparing and evaluating differences between various frequency bands remain challenging due to the absence of standardized parameters such as exposure conditions and duration. In contrast, dose assessment offers a simpler and more reliable approach. Materials and methods The dose assessment method was employed in this study to investigate the risks associated with sub-6 GHz electromagnetic radiation from 5G base stations on the male reproductive system. A classical human body model (Duke) was utilized, and an electromagnetic simulation environment was established based on the actual polarization direction of the exposed base stations and various body postures. This research explored the effects of field direction, posture, public population, and frequency on the specific absorption rate of the reproductive system. Results and conclusions While maintaining the same level of exposure, a higher frequency results in a reduced dosage on reproductive system. Further analysis reveals that, considering the public exposure threshold, the employment of higher frequency bands in 5G sub-6 GHz does not present a greater dosage on reproductive system compared to lower frequency bands. Consequently, with regard to dosage, there is no need for excessive concern among the general public regarding the impact of electromagnetic radiation emitted by 5G base stations operating below 6 GHz on male reproductive health.

LabVIEW based Mental Status Monitoring System for Cognitive Wellness

This paper delves into the analysis of various cognitive states by identifying the percentages of different types of brain waves, like alpha, beta, delta, and theta, present in an individual's EEG recording. These brain waves carry crucial information about an individual's cognitive health, and accurate readings are essential to classify and represent the signals accurately. To achieve this, the project aimed to develop a robust platform that utilizes LabVIEW software to obtain EEG signals and interpret cognitive health. The acquired data is meticulously preprocessed and filtered to obtain clean EEG signals, which are then subjected to several methods to determine the content of different brain waves present in the filtered EEG signals. Based on these values, the cognitive status of an individual can be accurately determined, providing valuable insights into their cognitive health. Understanding cognitive states through brain wave analysis has been an intriguing area of research, utilizing various electroencephalography (EEG) techniques to interpret neural activity. This paper aims to provide a detailed discussion on how cognitive states are mapped and interpreted based on brain waves. By exploring the characteristics of each brain wave frequency band, we elucidate their implications in cognitive processes such as attention, memory, and relaxation. This research aims to contribute in the advancement of cognitive neuroscience by consolidating current knowledge and identifying potential avenues for future research.

Efficient Decoding of Affective States from Video-elicited EEG Signals: An Empirical Investigation

Affect decoding through brain-computer interfacing (BCI) holds great potential to capture users’ feelings and emotional responses via non-invasive electroencephalogram (EEG) sensing. Yet, little research has been conducted to understand efficient decoding when users are exposed to dynamic audiovisual contents. In this regard, we study EEG-based affect decoding from videos in arousal and valence classification tasks, considering the impact of signal length, window size for feature extraction, and frequency bands. We train both classic Machine Learning models (SVMs and k -NNs) and modern Deep Learning models (FCNNs and GTNs). Our results show that: (1) affect can be effectively decoded using less than 1 minute of EEG signal; (2) temporal windows of 6 and 10 seconds provide the best classification performance for classic Machine Learning models but Deep Learning models benefit from much shorter windows of 2 seconds; and (3) any model trained on the Beta band alone achieves similar (sometimes better) performance than when trained on all frequency bands. Taken together, our results indicate that affect decoding can work in more realistic conditions than currently assumed, thus becoming a viable technology for creating better interfaces and user models.

Directed physiological networks in the human prefrontal cortex at rest and post transcranial photobiomodulation

Cerebral infra-slow oscillation (ISO) is a source of vasomotion in endogenic (E; 0.005–0.02 Hz), neurogenic (N; 0.02–0.04 Hz), and myogenic (M; 0.04–0.2 Hz) frequency bands. In this study, we quantified changes in prefrontal concentrations of oxygenated hemoglobin (Δ[HbO]) and redox-state cytochrome c oxidase (Δ[CCO]) as hemodynamic and metabolic activity metrics, and electroencephalogram (EEG) powers as electrophysiological activity, using concurrent measurements of 2-channel broadband near-infrared spectroscopy and EEG on the forehead of 22 healthy participants at rest. After preprocessing, the multi-modality signals were analyzed using generalized partial directed coherence to construct unilateral neurophysiological networks among the three neurophysiological metrics (with simplified symbols of HbO, CCO, and EEG) in each E/N/M frequency band. The links in these networks represent neurovascular, neurometabolic, and metabolicvascular coupling (NVC, NMC, and MVC). The results illustrate that the demand for oxygen by neuronal activity and metabolism (EEG and CCO) drives the hemodynamic supply (HbO) in all E/N/M bands in the resting prefrontal cortex. Furthermore, to investigate the effect of transcranial photobiomodulation (tPBM), we performed a sham-controlled study by delivering an 800-nm laser beam to the left and right prefrontal cortex of the same participants. After performing the same data processing and statistical analysis, we obtained novel and important findings: tPBM delivered on either side of the prefrontal cortex triggered the alteration or reversal of directed network couplings among the three neurophysiological entities (i.e., HbO, CCO, and EEG frequency-specific powers) in the physiological network in the E and N bands, demonstrating that during the post-tPBM period, both metabolism and hemodynamic supply drive electrophysiological activity in directed network coupling of the prefrontal cortex (PFC). Overall, this study revealed that tPBM facilitates significant modulation of the directionality of neurophysiological networks in electrophysiological, metabolic, and hemodynamic activities.

Envelope waves propagation in a one-dimensional tetratomic model of acoustic metamaterial

This paper explores the propagation of modulated waves in systems modelled as one-dimensional network whose elementary cell is constituted of four interacting subsystems. We derive the dispersion relation of its small amplitude plane waves as a quartic polynomial equation in the frequency squared; and numerically show the existence of four frequency bands. These include one acoustic band and three optical bands of which the middle one features the left-handedness. We also use the reductive perturbation method to reduce the discrete equations of motion of the system to the standard nonlinear Schrödinger, thereby predicting the possibility of the propagation modulated waves in the model. This prediction is firmly established through direct numerical simulations in which the analytical solutions of the nonlinear Schrödinger equation are used as input.

RBFNN-based UWB 4×4 MIMO Antenna Design with Compact Size, High Isolation, and Improved Diversity Performance for Millimeter-Wave 5G Applications

Abstract The millimeter-wave spectrum has emerged as a compelling solution to address the pressing need for high-datarate
capabilities in the development of 5G technology systems. Spanning between 20 GHz and 40 GHz, this spectrum
encompasses several prominent frequency bands crucial for advancing 5G applications. In light of this, our study
presents a thorough investigation into the design and performance of a compact cross-shaped slot broadband antenna,
complemented by a 4×4 Multiple-InputMultiple-Output (MIMO) configuration tailored for 5G operations at
28 GHz. The primary objective of this study is to develop an antenna system capable of achieving an extended bandwidth
ranging from 20 GHz to 40 GHz, effectively covering the crucial frequency bands essential for 5G millimeterwave(
mmWave) operations. To accomplish this, the optimization of antenna performance is meticulously carried out
using the Radial Basis FunctionNeuralNetworks (RBFNN) model. The RBFNNmodel serves as a robust tool for establishing
the intricate relationship between antenna dimensions, resonant frequency, and bandwidth. Subsequently,
the developed RBFNN model is employed to predict optimal antenna dimensions, ensuring resonance at 28 GHz and
meeting specified bandwidth targets. The single antenna is designed with a rectangular patch and a cross-shaped
slot and is constructed on the low loss Rogers RT Duroid 5880 substrate. This design reaches an outstanding bandwidth
of 19.5 GHz, and exhibits excellent radiation characteristics, with a high radiation efficiency of up to 99% and a
corresponding gain of 5.75 dB. The antenna’s design and performance are rigorously designed using HFSS software,
which is then compared to the results acquired using CST software. In addition, the proposed MIMO configuration
offers excellent performance in terms of key features such as small size (16 × 16.2 mm2), very wide bandwidth of 20
GHz, good gain of 6.75 high isolation exceeding 35 dB, and significant improvements in diversity performance measures
such as Envelope Correlation Coefficient (ECC), Diversity Gain (DG), Channel Capacity Loss (CCL), Total Active
Reflection Coefficient (TARC), and Mean Effective Gain (MEG). The potential of the proposed MIMO configuration
for high-speed applications is particularly remarkable. Practical verification of the MIMO configuration is carefully
carried out by fabrication andmeasurement. Experimental results strongly confirmthe effectiveness of the proposed
antenna design, establishing it as a competitive challenger for 5G technology.

Optical-pulse-based reconfigurable phase control for independent beamforming and band fusion in a dual-band phased array receiver.

This Letter proposes an optical-pulse-based reconfigurable phase control method, enabling a dual-band phased array receiver to operate in two modes: dual-band-independent operation and dual-band fusion. The method utilizes optical pulses and optical delay to compensate for phase differences across frequency bands. An electrical phase shifter is employed to compensate for phase residual in both bands. All phase operations to both bands are processed concurrently in one link, thereby maintaining inter-band phase coherence. Experimental results verify the ability of dual-band-independent beamforming and inter-band phase coherence maintaining. A four-channel dual-band (X- and Ku-band) phased array antenna (PAA) receiver is constructed to measure PAA patterns and demonstrate band fusion. The pulse compression results in all directions reveal a doubled improvement in range resolution, which shows the potential for enhancement of radar performance.

Learning optimal biomarker-guided treatment policy for chronic disorders.

Electroencephalogram (EEG) provides noninvasive measures of brain activity and is found to be valuable for the diagnosis of some chronic disorders. Specifically, pre-treatment EEG signals in the alpha and theta frequency bands have demonstrated some association with antidepressant response, which is well-known to have a low response rate. We aim to design an integrated pipeline that improves the response rate of patients with major depressive disorder by developing a treatment policy guided by the resting state pre-treatment EEG recordings and other treatment effects modifiers. First, we design an innovative automatic site-specific EEG preprocessing pipeline to extract features with stronger signals than raw data. We then estimate the conditional average treatment effect (CATE) using causal forests and use a doubly robust technique to improve efficiency in the estimation of the average treatment effect. We present evidence of heterogeneity in the treatment effect and the modifying power of the EEG features, as well as a significant average treatment effect, a result that cannot be obtained with conventional methods. Finally, we employ an efficient policy learning algorithm to learn an optimal depth-2 treatment assignment decision tree and compare its performance with Q-Learning and outcome-weighted learning via simulation studies and an application to a large multi-site, double-blind, randomized controlled clinical trial, EMBARC.

Power-law frequency-dependent Q simulations in viscoacoustic media using decoupled fractional Laplacians

Quantifying the seismic attenuation of wave propagation in the earth’s interior is essential for studying subsurface structures. Previous approaches for attenuation simulations (e.g., the standard linear solid and the fractional derivative model) are mainly based on the frequency-independent quality factor Q assumption. However, seismic attenuation in high-temperature and high-pressure regions usually exhibits power-law frequency-dependent Q characteristics. To simulate this Q effect in attenuative media, we derive a new viscoacoustic wave equation with decoupled fractional Laplacians in the time domain. Unlike the existing methods using relaxation functions to fit the power-law relationship in a specific frequency band, our equation is directly derived from the approximated complex modulus, which explicitly involves the reference quality factor and fractional exponent parameters. Furthermore, this equation contains two fractional Laplacians, which can easily simulate decoupled amplitude dissipation and phase distortion effects, making it amenable to Q-compensated reverse time migration. In the implementation, a Taylor-series expansion and a pseudospectral method are introduced to solve the fractional Laplacians with variable fractional exponents. Numerical experiments demonstrate the effectiveness of our method for power-law frequency-dependent Q simulations. As a forward-modeling engine, our derived viscoacoustic wave equation is a good supplement to the current Q simulation methods and it could be applied in many seismic applications, such as Q-compensated reverse time migration and full-waveform inversion.

EEG spectral power in developmental coordination disorder and attention-deficit/hyperactivity disorder: a pilot study.

Developmental coordination disorder (DCD) and attention-deficit/hyperactivity disorder (ADHD) overlap in symptoms and often co-occur. Differentiation of DCD and ADHD is crucial for a better understanding of the conditions and targeted support. Measuring electrical brain activity with EEG may help to discern and better understand the conditions given that it can objectively capture changes and potential differences in brain activity related to externally measurable symptoms beneficial for targeted interventions. Therefore, a pilot study was conducted to exploratorily examine neurophysiological differences between adults with DCD and/or ADHD at rest. A total of N = 46 adults with DCD (n = 12), ADHD (n = 9), both DCD + ADHD (n = 8), or typical development (n = 17) completed 2 min of rest with eyes-closed and eyes-open while their EEG was recorded. Spectral power was calculated for frequency bands: delta (0.5-3 Hz), theta (3.5-7 Hz), alpha (7.5-12.5 Hz), beta (13-25 Hz), mu (8-13 Hz), gamma (low: 30-40 Hz; high: 40-50 Hz). Within-participants, spectral power in a majority of waveforms significantly increased from eyes-open to eyes-closed conditions. Groups differed significantly in occipital beta power during the eyes-open condition, driven by the DCD versus typically developing group comparison. However, other group comparisons reached only marginal significance, including whole brain alpha and mu power with eyes-open, and frontal beta and occipital high gamma power during eyes-closed. While no strong markers could be determined to differentiate DCD versus ADHD, we theorize that several patterns in beta activity were indicative of potential motor maintenance differences in DCD at rest. Therefore, larger studies comparing EEG spectral power may be useful to identify neurological mechanisms of DCD and continued differentiation of DCD and ADHD.

Gravitational wave peeps from EMRIs and their implication for LISA signal confusion noise

Scattering events around the center of massive galaxies will occasionally toss a stellar-mass compact object into an orbit around the massive black hole (MBH) at the center, beginning an extreme mass ratio inspiral (EMRI). The early stages of such a highly eccentric orbit are not likely to produce detectable gravitational waves (GWs), as the source will only be in a suitable frequency band briefly when it is close to periapsis during each long-period orbit. This repeated burst of emission, firmly in the millihertz band, is the GW peep. While a single peep is not likely to be detectable, if we consider an ensemble of such subthreshold sources, spread across the Universe, together they may produce an unresolvable background noise that could obscure sources otherwise detectable by the Laser Interferometer Space Antenna. Previous studies of the extreme mass ratio signal confusion background focused either on parabolic orbits near the MBH or events closer to merger. We seek to improve this characterization by implementing numerical kludge waveforms that can calculate highly eccentric orbits with relativistic effects. Our focus is on orbits at the point of capture that are farther away from the MBH. Here we present the waveforms and spectra of peeps generated from recent calculations of EMRIs/extreme mass ratio bursts capture parameters and discuss how these can be used to estimate the signal confusion noise generated by such events. We demonstrate the effects of changing the orbital parameters on the resulting spectra as well as showing direct comparisons to parabolic orbits and why the GW ‘peep’ needs to be studied further. The results of this study will be expanded upon in a further paper that aims to provide an update on the EMRI signal confusion noise problem.

Piezo‐Turned Magnet Rotation for ELF/SLF Cross‐Medium Communication in Omni‐Direction

AbstractExtremely/super low frequency (ELF/SLF) electromagnetic (EM) waves offer efficient propagation in challenging cross‐medium environments. However, conventional coil antennas, when emitting ELF/SLF EM waves, face constraints related to size, radiation efficiency, and high power consumption. To overcome these limitations, a disc‐rod structured piezoelectric rotating resonator is proposed, which can turn a NdFeB permanent magnet disc into rotation with an impressive high‐speed up to 10 000 r min−1 via wobbling motion of the rod tip, effectively generating ELF/SLF magnetic field radiation via rotational oscillation other than common linear and swinging oscillation of the magnetic dipole moments. The piezo‐turned magnetic rotation (PTMR) method leads to a two to five‐fold enhancement in magnetic field emission compared to existing piezo‐actuated acoustic resonant antennas, and a 370 times higher emitting efficiency compared to the traditional coil antenna with a comparable size. In contrast to unidirectional EM wave radiation at their solely resonant frequencies, the PTMR antenna showcases omnidirectional B‐field radiation with continuous tunability in a dual frequency band spanning from 10 to 100 Hz. Moreover, an air–seawater cross‐medium magnetic field communication is successfully demonstrated. With outstanding performance metrics, the PTMR antenna emerges as a promising solution for efficient long‐distance ELF/SLF cross‐medium communication.

Age-dependent coupling characteristics of bilateral frontal EEG during desflurane anesthesia.

The purpose of this study is to investigate the age dependence of bilateral frontal electroencephalogram coupling characteristics, and find potential age-independent depth of anesthesia monitoring indicators for the elderlies.&#xD;Approach: We recorded bilateral forehead EEG data from 41 patients (ranged in 19-82 years old), and separated into three age groups: 18-40 years (n = 12); 40-65 years (n = 14), > 65 years (n = 15). All these patients underwent desflurane maintained general anesthesia. We analyzed the age-related EEG spectra, phase amplitude coupling (PAC), coherence and phase lag index (PLI) of EEG data in the states of awake, general anesthesia (GA), and recovery. &#xD;Main results: The frontal alpha power shows age dependence in the state of GA maintained by desflurane. Modulation index (MI) in slow oscillation-alpha and delta-alpha bands showed age dependence and state dependence in varying degrees, the PAC pattern also became less pronounced with increasing age. In the awake state, the coherence in delta, theta and alpha frequency bands were all significantly higher in the > 65 years age group than in the 18-40 years age group (p < 0.05 for three frequency bands). The coherence in alpha-band was significantly enhanced in all age groups in GA (p < 0.01) and then decreased in recovery state. Notably, the PLI in the alpha band was able to significantly distinguish the three states of awake, GA and recovery (p < 0.01) and the results of PLI in delta and theta frequency bands had similar changes to those of coherence. &#xD;Significance: We found the EEG coupling and synchronization between bilateral forehead are age-dependent. The PAC, coherence and PLI portray this age-dependence. The PLI and coherence based on bilateral frontal EEG functional connectivity measures and PAC based on frontal single-channel are closely associated with anesthesia-induced unconsciousness.&#xD.

Adjustable effective electromechanical coupling of Lamb wave resonator using AlN/Sc0.096Al0.904N composite films

Abstract With the rapid development of fifth-generation communication technology, there are more and more 5G frequency bands and their bandwidths are different. Therefore, many researchers devote themselves to the study of resonators with adjustable electromechanical coupling coefficient. In this paper, we apply composite films to the Lamb wave resonator with a double-IDT configuration to achieve adjustable effective electromechanical coupling coefficient (Keff2) of the first symmetric mode. The experimental results show that the Keff2 is adjusted from 3.82% to 6.32% and the Δf is adjusted from 41MHz to 63MHz by using the AlN/Sc0.096Al0.904N composite films with different thickness ratios. This method may be an efficient way to adjust the bandwidth of the filter to meet the needs of different frequency bands.

Ultra-wideband RCS reduction realized by a coding diffusion metasurface

In this study, a coding diffusion metasurface (CDMS) based on a circular-polarization (CP)-maintaining metasurface is proposed for radar cross-section (RCS) reduction. The CP-maintaining metasurface can achieve ultra-wideband CP-maintaining reflection, and its main reflection phase under CP incidence can be adjusted at will by the Pancharatnam-Berry phase generated by the rotation of its unit cell, so it can be used to design CDMS. Thus, based on the CP-maintaining metasurface, the 2-bit CDMS is proposed. The simulated and measured results demonstrate that the CDMS can achieve highly effective and ultra-wideband RCS reduction under arbitrarily polarized incidences, compared with a pure metallic plate of the same size, its RCS can be reduced by more than 10 dB under normal incidence in the ultra-wide frequency band of 7.1-33.6 GHz with a relative bandwidth of 130.2%; moreover, when the incident angle is increased to 40°, an ultra-wideband RCS reduction can still be achieved.

Polarization-insensitive perfect absorption in van der waals hyper-structure

Infrared perfect absorption has been widely investigated due to its potential applications in photodetectors, photovoltaics and medical diagnostics. In this report, we demonstrate that at particular infrared frequencies, a simple planar structure made up of graphene-hexagonal Boron Nitride (hBN) hyper-structure is able to nearly perfectly absorb incident light irrespective of its polarization (Transverse-Magnetic TM, or Transverse-Electric TE). By using this interferenceless technique, the hyper-structure achieves nearly zero reflectance at a wide range of angles in a narrow frequency band. We analytically predict the condition of achieving such an important feature of perfect absorption for both TM and TE polarizations. Interestingly, the infrared perfect absorption can be redshifted by increasing the thickness of the hBN layers and blueshifted by increasing the graphene’s chemical potential. Such flexible control of infrared perfect absorption offers a new tool for controlling electromagnetic waves and has potential applications in photodetection and other light control applications.

Particle-hole instabilities in photonic time-varying systems

Photonic systems with time-varying modulations have attracted considerable attention as they allow for the design of non-reciprocal devices without the need for an external magnetic bias. Unlike time-invariant systems, such modulations couple modes with different frequencies. Here, we discuss how this coupling and particle-hole symmetry may lead to the resonant interaction of positive and negative frequency oscillators. To illustrate this idea, we analyze a dispersive spacetime crystal described by a Drude-Lorentz model with a traveling-wave modulation. Our findings demonstrate that the interaction between positive and negative frequency bands can induce parametric instabilities under certain conditions, stemming from the interplay between dispersion and spacetime modulations. In particular, we find that material dispersion creates the conditions for the formation of instabilities for arbitrarily small modulations speeds in the absence of dissipation mechanisms.

Damping performance of finite microperforated plates using multi-size and spatial distributions of perforations

In the context of structural dynamics, recent works by the authors showed that microperforations can be used to mitigate vibration. Microperforated plates (MPP) have been shown to exhibit substantial added damping arising from fluid-structure interactions and visco-thermal effects in the boundary layers of the perforations during relative motion between the solid and the fluid contained in the perforations. The added damping reaches a maximum for a characteristic frequency, depending only on the diameter of the perforation. Choosing the diameter of the perforation so that the characteristic frequency coincides with a given natural frequency of the plate reduces the contribution of the associated plate mode. However, the MPP studied had a single set of perforations homogeneously distributed throughout the structure. In this work, it is proposed to extend the added damping to several modes of the plate by using MPP with multi-size perforations and an optimized spatial distribution of these perforations. As an extension of the previous vibratory model of the authors, the dynamics of MPP with perforations of multiple sizes based on a homogenization model is established. In addition, the effect of the spatial distribution of perforations on the additional damping is captured by including a spatially dependent perforation ratio in the model. Experimental measurements on MPP validate the proposed analytical models. The results show that (i) MPP with multiple-size perforations feature a wider effective damping frequency band, and (ii) the added damping is accentuated when the perforations are distributed in the zone of the antinodes of the considered modes. Thus, by combining the two effects, it is possible to achieve MPP that effectively reduce the vibratory responses on several modes.

Microwave Antenna Optimization for Low Latency and High Throughput Communication Systems

This paper presents a comprehensive exploration of microwave antenna optimization strategies aimed at achieving low latency and high throughput in modern communication systems. With the escalating demand for real-time applications and data-intensive services, the optimization of microwave antennas has become imperative to meet the stringent requirements of responsiveness and efficiency. The abstract delves into various facets of antenna optimization, including design parameters, signal processing techniques, and deployment considerations, all geared towards minimizing latency and maximizing throughput. Through a thorough review of existing literature and practical insights from real-world deployments, this research aims to provide valuable guidance for engineers and researchers in designing and implementing optimized microwave antennas for next-generation communication networks. By examining the intricate interplay between antenna design, signal processing algorithms, and deployment strategies, this paper elucidates the challenges and opportunities in achieving low latency and high throughput in microwave communication systems. Furthermore, it highlights the significance of factors such as gain, beamwidth, polarization, frequency band selection, multiple-input multiple-output (MIMO) systems, beamforming, adaptive coding and modulation (ACM), antenna placement, tower height, and line-of-sight considerations in optimizing antenna performance. The findings presented in this paper contribute to advancing the understanding of microwave antenna optimization and offer practical insights into enhancing the responsiveness, efficiency, and reliability of modern communication networks.

A multiscale symbolic approach to decoding delta and ripple oscillation bands as biomarkers for epileptiform discharges.

We use a multiscale symbolic approach to study the complex dynamics of temporal lobe refractory epilepsy employing high-resolution intracranial electroencephalogram (iEEG). We consider the basal and preictal phases and meticulously analyze the dynamics across frequency bands, focusing on high-frequency oscillations up to 240 Hz. Our results reveal significant periodicities and critical time scales within neural dynamics across frequency bands. By bandpass filtering neural signals into delta, theta, alpha, beta, gamma, and ripple high-frequency bands (HFO), each associated with specific neural processes, we examine the distinct nonlinear dynamics. Our method introduces a reliable approach to pinpoint intrinsic time lag scales τ within frequency bands of the basal and preictal signals, which are crucial for the study of refractory epilepsy. Using metrics such as permutation entropy (H), Fisher information (F), and complexity (C), we explore nonlinear patterns within iEEG signals. We reveal the intrinsic τmax that maximize complexity within each frequency band, unveiling the nonlinear subtle patterns of the temporal structures within the basal and preictal signal. Examining the H×F and C×F values allows us to identify differences in the delta band and a band between 200 and 220 Hz (HFO 6) when comparing basal and preictal signals. Differences in Fisher information in the delta and HFO 6 bands before seizures highlight their role in capturing important system dynamics. This offers new perspectives on the intricate relationship between delta oscillations and HFO waves in patients with focal epilepsy, highlighting the importance of these patterns and their potential as biomarkers.