Ultra-wideband Pulse Research Articles

Model of spatiotemporal coherent summation of ultra-wideband chaotic radio pulses formed by independent emitters

A model of spatiotemporal summation of ultra-wideband chaotic radio pulses is proposed. The feasibility of using this model for analyzing scenarios of time-coherent radiation from independent sources of ultra-wideband chaotic radio pulses in wireless ultra-wideband systems is substantiated. Two scenarios are considered: where the distance between receiving point and emitters is much greater than the typical size of a group of emitters and where the receiving point is located between the emitters. Distributions of the total pulse energy in space for these scenarios are obtained.

Radiofrequency Diagnostic of the Decaying Plasma in the “Gigantic” Coaxial Line at the Large Plasma Device

At the large-scale Krot facility (Gaponov-Grekhov Institute of Applied Physics of the Russian Academy of Sciences), a new device was developed for laboratory simulations of the effects of the interaction of ultrawideband electromagnetic pulses with the partially ionized atmosphere and ionosphere: the “gigantic” coaxial line with a length of 10 m and diameter of 1.4 m that is filled by the decaying plasma of the inductive discharge. Two radiofrequency methods of wave diagnostics used in the device are described, the cutoff method and the wave interferometer, which can be used to determine the electron density of the plasma in the line in a wide range of values, Ne = 107–1011 cm–3. The measurement results are compared with the values obtained by the contact diagnostic, a probe with a microwave resonator. The interferometric method is implemented taking into account the nonuniform distribution of plasma density both along and across the transmission line, which, in the working range of pulsed and continuous diagnostic signals, is an oversized waveguide. The specific features of application and the limitations of the contact (probe) and contactless (wave) methods of diagnostics are discussed, taking into account the nonuniform plasma distribution in the coaxial line and the specific features of its construction.

Development of the algorithm for determining the thickness of the structural layers of the non-rigid pavement and searching for local inclusions using sub-surface georadiolocation methods

Problem. The article is part of the authors' research in the field of road construction using GPR technologies. Ensuring a certain level of pavement reliability on highways requires the development of methods and means for continuous information acquisition and processing in real time, taking into account the parameters of structural heterogeneity, heterogeneity of physical and mechanical parameters of structures, as well as their changes over time. The solution of this problem is limited by the complexity of tasks of obtaining and interpreting the data of subsurface sensing and the associated errors in determining the parameters of structures, imperfection of methods of flaw detection of structures with subsurface inhomogeneities, multifactorial tasks of estimation of physical and mechanical parameters of multicomponent materials. Goal. Improving the accuracy and reliability of determining the boundaries of layers of non-rigid pavement structure, which have a low level of electrodynamic contrast due to interpenetration of layer materials or changes in their physical and mechanical properties. The solution of this problem is connected with the development of a method of obtaining reflected GPR signals and the improvement of algorithms for their processing. Methodology. The development of methods for the analysis of the electromagnetic field with a variable state of polarization makes it possible to assess the localization of violations of the integrity of the pavement structure at a qualitatively new level and allows the positioning of small inclusions even with a slight contrast in the dielectric constant. The proposed method of recording the reflection of an ultra-wideband GPR pulse signal at different polarizations is implemented by measuring the reflected signal from a metal sheet at oblique incidence and parallel polarization, recording the reflected pulse at perpendicular polarization, followed by measuring the reflection coefficient from the structure of the nonrigid pavement under study at parallel and perpendicular polarization. The electrophysical parameter recovery procedure is based on the solution of inverse scattering problems and ensures the accuracy of determining the low-contrast boundaries of the pavement structure and increases the accuracy of positioning subsurface heterogeneities. GPR signal processing algorithms are based on procedures for analyzing their polarization state, which allows determining the geometric parameters of subsurface heterogeneities. Practical value. The combination of the obtained results increases the accuracy and reliability of the results of GPR diagnosis and assessment of the condition of non-rigid pavement based on the most complete and reliable information about the subsu

Aspects of Elite Female Football Players' Training Loads and Sleep Variations.

The current study investigated the associations between female football players' training loads and their sleep variations. The sample included 21 female elite football players from a Norwegian top-league club with a mean age of 24 years (±2.8). Sleep duration, sleep quality, and training load were monitored every day over 273 consecutive days with a Somnofy sleep monitor based on ultra-wideband (IR-UWB) pulse radar and Doppler technology, and a FIFA-approved STATSports APEX 10 Hz GPS tracking system monitoring players' training loads. A multivariate analysis of variance (MANOVA) was conducted to investigate the relationships between the players' training loads and sleep. It was revealed that very high training loads were associated with reduced time in bed (p = 0.005), total sleep time (p = 0.044)), and rapid eye movement (p < 0.001). The present findings show that the female football players' sleep was disrupted when the training load, based on total distance (TDI), was very high. It appears to be a point where their sleep is somewhat consistent through low, medium, and high training loads, but with disrupted sleep when the training load reaches a very high level. Considering the reduced TIB after a very high training load, there should be suggested strategies to improve their sleep, such as extended TIB, to aid in longer TST and improved recovery.

Pulse Radiation Characteristics Prediction Method of Vivaldi Antenna based on Dipole Array

This paper presents a theoretical method to estimate the pulse radiation characteristics of Vivaldi antennas. Based on the surface current distribution and the ultra-wideband radiation principle, Vivaldi antenna is equivalently modeled as a dipole array, and the pulse radiation characteristics of a single Vivaldi antenna are brought out utilizing the spatial superposition approach. Then, the influences and results of the Vivaldi antenna pulse characteristics prediction with different construction ways of the dipole array and element numbers are furthermore investigated. Next, a quadratic spatial superposition technique is employed to complete the theoretical prediction for time-domain radiation characteristics of Vivaldi antenna arrays. Experiments and simulations are conducted separately to verify the proposed method for both single Vivaldi antenna and array. The validated results demonstrate that the dipole array-based theoretical prediction method can effectively capture the pulse radiation characteristics for both individual Vivaldi antenna and array operating in different modes, thereby addressing challenges associated with estimating radiation characteristics in ultra-wideband pulse applications.

Method for controlling the radiation pattern of an underground radiation antenna

Currently, communication and signaling means of underground structures are implemented by wire lines. In addition, radio communications of various frequency ranges are used, operating within line of sight and having the disadvantage of interrupting radio communications in emergency situations. Low-speed broadcast systems using ultra-low frequencies are also used. This work shows the possibility of using subsurface georadar technology to organize a faster circular warning system for underground structures. Existing GPR instruments using ultra-wideband pulses in the 1 to 50 MHz band reach depths of several hundred meters. In this case, control of the radiation pattern of the underground radiation antenna is possible both in the horizontal and azimuthal planes. Modern methods of controlling antenna-feeder devices used in georadar are shown, allowing to improve user qualities for various applications. With the development of these methods, additional areas of application of these devices appear: in underground radio communication systems, for identifying low-contrast objects, for ground penetrating radar from aircraft. Based on the method for controlling the directional pattern of underground radiation antennas in the horizontal plane for stationary or specialized devices, a new method has been developed to control the main lobe of the directional pattern in the azimuthal plane of the transmitting antenna. A method has been proposed for controlling the radiation pattern in various technical implementations, which allows changing the position of the radiation pattern both discretely and smoothly. Examples of using the developed method for controlling the radiation pattern of an underground radiation antenna for the implementation of geophysical instruments of various types have been shown. The possibilities of locating underground radiation antennas in various soils have been proposed when using them in circular warning systems for underground structures.

Increasing the probing depth of pulsed GPR by reducing the antenna impedance

At the present time, dipole antennas with resistively loaded vibrators are widely used in pulsed georadar. The main property of such antennas is the emission of an electromagnetic wave into the subsurface medium with rapid attenuation of the ultra-wideband pulse to the end of the vibrators without reflection. When the total resistance of the vibrator decreases below 200 Ohms, parasitic self-oscillations appear in this antenna, limiting the increase in power supplied to the antenna. Development of a dipole antenna for subsurface ground penetrating radar with the ability to reduce the antenna impedance below 200 Ohms to increase the radiated power and increase the depth of ground penetrating radar. The design of a dipole antenna with several resistively loaded vibrators connected in parallel is proposed. The total resistance of a single vibrator is selected based on the stability requirements to prevent parasitic self-oscillations, but the impedance of the dipole antenna decreases in proportion to the number of connected vibrators. A dipole antenna with five dipoles connected and arranged parallel to each other has a gain 10 dB higher compared to a dipole with a single resistively loaded dipole. Compared to a plate antenna 3 meters long and 25 cm wide, a five-vibrator dipole antenna of the same length has a gain of 3.3 dB higher. Another advantage of the proposed antenna is its higher resolution. At the same time, insulated vibrators made of flexible conductors allow twisting to reduce the overall diameter of the dipole antenna, which allows its use in difficult engineering and geological conditions. Experiments with three-meter dipole antennas showed an increase in sounding depth in the Moscow region from 14 to 20 meters.

Transformation of the Shape and Spectrum of an Ultrawideband Electromagnetic Pulse in a “Gigantic” Coaxial Line Filled with Magnetized Plasma

A propagation of ultrawideband electromagnetic pulses (UWB EMPs) through magnetized plasma has been experimentally studied using a “gigantic” coaxial line, which has been developed at IAP RAS for laboratory modeling of ionospheric effects. This coaxial line is 1.4 m in diameter and 10 m in length and is installed inside the chamber of the large-scale Krot plasma device. The line can be filled with rf inductively coupled plasma, magnetized or not. It allows one to explore the propagation of UWB EMPs in plasma along a long path without refraction and divergence and obtain a physical picture of EMP transformation. Under conditions where the duration of the UWB EMP is comparable to the period of electron plasma oscillations (fp−1), the period of cyclotron rotation of electrons (fc−1), or even significantly shorter, a complex of effects of transformation of the waveform and frequency spectrum of the pulse occurs. Without ambient magnetic field, a UWB EMP is distorted due to the effects of the cutoff and frequency dispersion. In dense magnetized plasma, i.e., when fp &gt;&gt; fc, the UWB EMP breaks into two wave packets, the high-frequency one (f &gt; fp) and low-frequency one (f &lt; fc). In rare magnetized plasma (fp &lt;&lt; fc), the cyclotron absorption produces a long train of damped oscillations at a frequency close to the cyclotron frequency fc following the UWB EMP.

UI-MoCap: An Integrated UWB-IMU Circuit Enables 3D Positioning and Enhances IMU Data Transmission.

While inertial measurement unit (IMU)-based motion capture (MoCap) systems have been gaining popularity for human movement analysis, they still suffer from long-term positioning errors due to accumulated drift and inefficient data transmission via Wi-Fi or Bluetooth. To address this problem, this study introduces an integrated ultrawideband (UWB)-IMU system, named UI-MoCap, designed for simultaneous 3D positioning as well as wireless IMU data transmission through UWB pulses. The UI-MoCap comprises mobile UWB tags and hardware-synchronized UWB base stations. Each UWB tag, a compact circular PCB with a 3.4cm diameter, houses a nine-axis IMU unit and a UWB transceiver for data transmission. The base stations are equipped with a UWB transceiver and an Ethernet controller, ensuring efficient reception and management of messages from multiple tags. Experiments were conducted to evaluate the system's validity and reliability of 3D positioning and IMU data transmission. The results demonstrate that UI-MoCap achieves centimeter-level 3D positioning accuracy and maintains consistent positioning performance over time. Moreover, UI-MoCap exhibits high update rates and a minimal packet loss rate for IMU data transmission, significantly outperforming Wi-Fi-based transmission techniques. Future work will explore the fusion of UWB and IMU technologies to further enhance positioning performance, with a focus on human movement analysis and rehabilitation applications.

Design, Simulation, and Fabrication of a 500 kV Ultrawideband Coaxial Matched Load and Its Connectors for Fast Transient Pulse Measurement Systems

In the past few decades, Pulsed Power (PP) has been one of the fastest growing technologies, with more and more systems frequently emerging in domains such as civil, medical and military. These systems are based on high-voltage pulses, up to several hundreds of kilovolts, with temporal parameters ranging from microsecond levels to sub-nanosecond levels. One of the biggest challenges in this technology is the accurate and precise measurement of the generated PP. The PP measurement systems must possess high-voltage and wideband properties simultaneously, which is often conflicting. The central elements of a PP measurement system are a voltage divider and a termination load. The work presented in this article is dedicated to the second element of the PP measurement system. This paper describes the development of a 50 Ω coaxial termination load and its connectors for a high power ultrawideband (UWB) pulse measurement systems. The principle roles of these devices are to serve as a dummy matched load for the former and to facilitate the connections between different components of the pulse measurement system for the latter. These devices are designed to withstand pulse voltage amplitudes at least up to 500 kV with temporal parameters, such as rise time and pulse duration, varying from nanosecond to sub-nanosecond ranges. The main challenge in the development of a high-voltage UWB termination load is the tradeoff between the high-voltage and wideband characteristics, both of them requiring opposite dimensional aspects for the load device. This challenge is overcame by the special exponential geometry of the load device. The design employs a 30 cm long low-inductance tubular ceramic 50 Ω resistor, enclosed in a critically dimensioned shielding conductor of an exponential inner profile. This shrinking coaxial structure makes it possible to maintain a good level of matching all along the 50 Ω load. The results obtained through 3D electromagnetic modeling and vector network analyzer measurements show good agreement and confirm the reflection coefficient below −27 dB up to at least 2.5 GHz for the load device. Moreover, calculations demonstrate that the load device is very well adapted for nanosecond and sub-nanosecond pulses with voltage peaks as high as 500 kV. These results demonstrate the high-voltage and UWB properties of the developed load device and prove the utilization of this device in the measurement systems for the accurate and precise measurements of the PP.

Tightly coupled arrays with time-domain beam scan for the radiation of high-power ultrawideband electromagnetic pulses.

In this paper, a kind of tightly coupled array (TCA) with time-domain beam scan is developed for the radiation of high-power ultrawideband (UWB) electromagnetic pulses, and the peak-power pattern is proposed to characterize the directivity. First, the active voltage standing wave ratio (AVSWR) bandwidth of the TCA is optimized, which is the precondition for the beam scan. It indicates that the lower-cutoff frequency (LCF) is inversely proportional to the total length of the whole array; an increase in the distance between the array and the ground plane could remarkably reduce the LCF; and an increase in the element number can also decrease the LCF because of the increase in length, but more elements would make the center elements difficult to match in the low-frequency range, so there is a limitation on the number of elements for a certain LCF. Based on these results, a six-element linear array is designed. Then, the definition of the peak-power pattern is proposed to characterize the directivity of the UWB pulsed antenna. Finally, the optimized six-element array is developed, and the measured working band is 276 MHz-6.4GHz (AVSWR < 3). The effective potential gain is 1.76, and it improves by 51.7% with a reduction in the aperture area by 68.4% compared with the previous TCA, which means that the aperture efficiency is remarkably improved. The half-power beam width of the developed TCA with the scan angle of 0° is 45°. The time-domain beam scan could be performed with time-delay feeding lines, and the maximum scan angle is over ±30° in the E-plane. The developed TCA can be applied for the generation of high-power electromagnetic environments for the study of intentional electromagnetic interference.

GENERATION OF RECTANGULAR NANOSECOND ELECTROMAGNETIC PULSES WITH A PICOSECONDS RISE FRONT

A method for generation of ultra-wideband electromagnetic pulses with a nanosecond duration and a picosecond rise time has been studied. The emitter is a horn antenna with a photoconductive switch irradiated by laser pulses. It has been shown that the duration of ultra-wideband electromagnetic pulses is determined by the length of the antenna and the semiconductor material, and the rising front is determined by the front of the laser pulses used to initiate the photoconductive switch. The work shows typical pulse durations of ~1 ns with a rising edge of up to ~34 ps.

Modal Filter Based on a Microstrip Line With Two Side Conductors Grounded at Both Ends

This article presents a modal filter (MF) based on a microstrip line with two side conductors grounded at both ends. New analytical expressions for calculating the time response in such a structure are given. For their validation, an MF prototype was made and the transmission coefficient was measured in the frequency range from 0 to 12 GHz. In addition, the full-wave electrodynamic simulation and the analysis based on the transmission line theory were carried out. The MF frequency responses were converted into time domain responses in the Advanced Design System. At the MF output, the responses to an ultra-wideband pulse, a high-frequency damped sinusoid, and a sinusoid with Gaussian modulation were analyzed. The results for the analytical model are in good agreement with the results of measurements and simulations by the two approaches. It was experimentally proven that the structure under study provides the protection of electrical circuits from different types of interference by separating them in time and decreasing their effect on the components. Finally, signal integrity was evaluated for two data rates. It was found that the MF under investigation may be used in signal circuits up to 1 Gb/s.

A photo-controlled, all-solid, and frequency-tunable ultra-wideband pulse generator.

With the continuous exploration of the bioelectric effect, nanosecond and picosecond pulsed electric fields used in cancer therapy and drug introduction have attracted great attention. In this paper, an ultrashort pulsed electric field generator is proposed, which connects two photoconductive semiconductor switches in parallel to generate unipolar and bipolar pulses. We described the experimental scheme of the generator and the simulation of the radio frequency combiner. A 532nm laser with pulse widths of 1ns and 500ps is used to trigger the photoconductive semiconductor switches. The experimental results show that the scheme can achieve adjustments of 357 and 720MHz for the center frequency and the 3 dB bandwidth, respectively. The results confirm that this proposed scheme can be used for unipolar/bipolar frequency-adjustable ultra-wideband pulse generation.

Simulation Research on the Effect of Ultra-wideband Pulses with a Global Positioning System Antenna

With the development of drone technology, drones are gradually being applied in various industries. But with the increasingly complex electromagnetic environment, the impact of electromagnetic interference on drones is also gradually increasing. The GPS is one of the important components of unmanned aerial vehicles. This paper establishes a 1.58 GHz frequency band circularly polarized microstrip patch antenna model. It uses this model to simulate the coupling effect of UWB pulses on the front door of the GPS. UWB pulses with different polarization directions and incidence angles were selected for coupling simulation research. The results indicate that the coupling effect is closely related to the polarization direction and incident direction angle of the pulse, and the coupling signal spectra under different conditions are obtained. This result guides subsequent experiments on the coupling effect of UWB pulses on unmanned aerial vehicles and research on the coupling mechanism.

An antenna for radiating and receiving short-pulse ultra-wideband signals

This paper presents a design of the antenna with an expandable slot for effective radiating and receiving the ultra-wideband (UWB), short-pulse signals. The offered design of the antenna allows creating an interferential electromagnetic field of a bipolar pulse in an equivalent general antenna aperture. A quantitative and quality evaluation of efficiency of proposed antenna design is performed. It is shown that an application of the given antenna allows increasing the propagation range of the pulsed UWB signals.

Моделирование энергетического приемника для систем сверхширокополосной хаотической радиосвязи

The problem of modeling an energy receiver of ultra-wideband chaotic radio pulses for chaotic radio communications is studied. As is shown, a combination of numerical and analytical modeling completes the problem of calculating characteristics of ultra-wideband chaotic communication systems. On the one hand, the numerical method is effective for calculating receiving systems with short radio pulses, and with an increase in the duration of radio pulses Tp the rate of the method decreases proportionally, whereas technical requirements for the computing equipment increase proportionally, so the operation time increases faster than Tp. On the other hand, the accuracy of the analytical solution, which is insufficient in the case of short radio pulses, grows proportion-ally with an increase in the duration of the radio pulses. Thus, in this problem, the numerical and analytical methods ideally complement each other. It is shown that the accuracy of the approximate analytical solution for the optimal threshold and the error probability becomes sufficient for engineering calculations at the values of the number of freedom degrees (processing gain) of chaotic radio pulses B  200. The combination of numerical and analytical modeling methods can significantly simplify tiresome modelling of chaotic communication systems, for example, those that provide maximum range by increasing the signal length.

The effect of bio-electro-magnetic-energy-regulation therapy on sleep duration and sleep quality among elite players in Norwegian women's football.

The current study investigated if physical loads peak on game days and if Bio-Electro-Magnetic-Energy-Regulation (BEMER) therapy is affecting sleep duration and sleep quality on nights related to game nights among elite players in Norwegian women's elite football. The sample included 21 female football players from an elite top series club with a mean age of ~24 years (± 2.8). Sleep was measured every day over a period of 273 consecutive days with a Somnofy sleep monitor based on ultra-wideband (IR-UWB) pulse radar and Doppler technology. The current study was conducted as a quasi-experiment, where each player was their own control based on a control period that lasted for 3 months, and an experimental period that lasted for 5 months. Accordantly, the time each player spent with BEMER therapy was used as a control variable. Multivariate analyses of variance using FFMANOVA and univariate ANOVA with False Discovery Rate adjusted p-values show that physical performance (total distance, distance per minute, sprint meters >22.5 kmh, accelerations and decelerations) significantly peak on game day compared with ordinary training days and days related to game days. The results also show that sleep quantity and quality are significantly reduced on game night, which indicate disturbed sleep caused by the peak in physical load. Most sleep variables significantly increased in the experiment period, where BEMER therapy was used, compared to the control period before the introduction of BEMER therapy. Further, the analyses show that players who spent BEMER therapy >440 h had the most positive effects on their sleep, and that these effects were significantly compared to the players who used BEMER therapy <440 h. The findings are discussed based on the function of sleep and the different sleep stages have on recovery.

Spectrally Efficient UWB Pulse Shaping Based on Polynomially Weighted Gaussian Pulses With Maximally Flat Amplitude Spectra

This letter presents a new class of symmetric waveforms that is suitable for spectrally efficient ultra-wideband (UWB) pulse shaping. The waveforms are based on polynomially weighted Gaussian, where polynomials are constructed by imposing maximum flatness at the peak of the pulse’s amplitude spectrum. To perform pulse shaping, frequency shift and bandwidth scaling are applied. The proposed approach is illustrated with the design of UWB pulses that fill the FCC masks and provide high spectral efficiency. Compared to other Gaussian-based UWB waveforms, the proposed pulses have significantly higher spectral efficiency and slightly lower energy concentration.

The application of ultrawideband technology in future wireless communications and practical exploration

An innovative form of wireless communication technology is called ultra-wideband technology. By directly modulating impulse pulses with extremely rapid rise and fall times, it is possible to create signals with bandwidths of the order of GHz. It has the benefits of being insensitive to channel fading, low power spectral density of the transmitted signal, low interception capability, low system complexity, and the ability to provide several centimeters of positioning accuracy. It also resolves the main propagation issues that have plagued traditional wireless technology for many years. Early high-speed data transmission in close proximity utilised ultra-wideband; more recently, foreign nations have started using its sub-nanosecond ultra-narrow pulse for close-range indoor positioning. Traditional wireless communication modulates signals to various frequency bands using various carrier frequencies, and within a given range, the carrier wave's frequency and power will change. Ultra-wideband wireless communication does not require a carrier wave, but uses pulsed signals to transmit information, where pulsed signals are those that are generated and disappear in a very short time, from a few hundred microseconds to less than a few nanoseconds. Thirdly, it can be positioned with high accuracy and has good resistance to multipath effects in timing. Ultra-wideband technology wireless communication systems generally work at sub-nanosecond pulse widths, and thus have sub-nanosecond time resolution, and its multipath resolution is correspondingly less than 30 cm, the signal will be received in the formation of a 1-nanosecond time reception window, only receive the signal within the reception window, the multipath interference has very good resistance. Fourthly, it has a greater penetration capability. Ultra-wideband pulses have a low frequency, the lowest of any wireless signal with the same absolute bandwidth, so they have greater penetration capability. Fifthly, the structure is simple, and the cost is low. The wireless communication system of ultra wideband technology does not change the traditional carrier wave to realize information transmission. The wireless communication system uses up conversion circuit, down conversion circuit, intermediate frequency circuit and various filters. The system structure is simple, and communication is relatively tolerant and easy. Therefore, the cost of wireless communication using ultra wideband technology is much lower.