Analysis and Modeling of Broadband CMOS Monolithic Balun up to Millimeter-Wave Frequencies

The implementation of broadband monolithic baluns based on CMOS technology is investigated. The configuration and parameterized layout are analyzed. Then,a wide-band lumped element equivalent circuit model accounting for all necessary physical effects is proposed and model parameters are extracted, with high accuracy in a broadband frequency range ,via combination of physical formula and fitting optimization. Two baluns were implemented with TSMC＇s one-poly eight-metal （1P8M） 0.13μm mixed-signal （MS）/RF CMOS process. The S-parameters of these two baluns were measured using a vector network analyzer. The measured results agree well with the modeled parameters up to millimeter-wave frequencies.

Multiscale Feature Fusion for Gesture Recognition Using Commodity Millimeter-Wave Radar

Gestures are one of the most natural and intuitive approach for human-computer interaction.Compared with traditional camera-based or wearable sensors-based solutions,gesture recognition using the millimeter wave radar has attracted growing attention for its characteristics of contact-free,privacy-preserving and less environmentdependence.Although there have been many recent studies on hand gesture recognition,the existing hand gesture recognition methods still have recognition accuracy and generalization ability shortcomings in shortrange applications.In this paper,we present a hand gesture recognition method named multiscale feature fusion(MSFF)to accurately identify micro hand gestures.In MSFF,not only the overall action recognition of the palm but also the subtle movements of the fingers are taken into account.Specifically,we adopt hand gesture multiangle Doppler-time and gesture trajectory range-angle map multi-feature fusion to comprehensively extract hand gesture features and fuse high-level deep neural networks to make it pay more attention to subtle finger movements.We evaluate the proposed method using data collected from 10 users and our proposed solution achieves an average recognition accuracy of 99.7%.Extensive experiments on a public mmWave gesture dataset demonstrate the superior effectiveness of the proposed system.

Co-Sharing Waveform Design for Millimeter-Wave Radar Communication Systems

Millimeter-wave(mmWave)radar communication has emerged as an important technique for future wireless systems.However,the interference between the radar signal and communication data is the main issue that should be considered for the joint radar communication system.In this paper,a co-sharing waveform(CSW)is proposed to achieve communication and radar sensing simultaneously.To eliminate the co-interference between the communication and sensing signal,signal splitting and processing methods for communication data demodulation and radar signal processing are given respectively.Simulation results show that the bit error rate(BER)of CSW is close to that of the pure communication waveform.Moreover,the proposed CSW can achieve better performance than the existing waveforms in terms of range and velocity estimation.

Remote Control of Bovine Catalase Activity with Specific Frequencies of Human and Bovine Catalase with and without Bound NADP+

Remote control enzyme technology is widely used today through resonance. In this study, we showed that the use of frequencies of the catalase enzyme itself to increase enzymatic rate is successful not only in test tubes but also remotely. The present study also suggests that, under optimal temperature, the use of bovine catalase frequency (the specific frequency of that enzyme) has a superior rate promoting vibration than the human catalase frequency, and so increases very significantly the chemical rate of bovine catalase (about 120% at 40˚C). It also suggests that bovine catalase subjected to bovine and human frequencies with catalase bound NADP+ experienced more resonance weight towards NADP+ and so were more slowly reduced back to catalase bound NADPH, increasing compound II formation rate, and slowing down the catalase activity rate.

A Single-Board Integrated Millimeter-Wave Asymmetric Full-Digital Beamforming Array for B5G/6G Applications

In this article,a single-board integrated millimeter-wave(mm-Wave)asymmetric full-digital beamforming(AFDBF)array is developed for beyond-fifth-generation(B5G)and sixth-generation(6G)communications.The proposed integrated array effectively addresses the challenge of arranging a large number of ports in a full-digital array by designing vertical connections in a three-dimensional space and successfully integrating full-digital transmitting(Tx)and receiving(Rx)arrays independently in a single board.Unlike the traditional symmetric array,the proposed asymmetric array is composed of an 8×8 Tx array arranged in a square shape and an 8+8 Rx array arranged in an L shape.The center-to-center distance between two adjacent elements is 0.54k0 for both the Tx and Rx arrays,where k0 is the free-space wavelength at 27 GHz.The proposed AFDBF array possesses a more compact structure and lower system hardware cost and power consumption compared with conventional brick-type full-digital arrays.In addition,the energy efficiency of the proposed AFDBF array outperforms that of a hybrid beamforming array.The measurement results indicate that the operating frequency band of the proposed array is 24.25–29.50 GHz.An eight-element linear array within the Tx array can achieve a scanning angle ranging from-47°to+47°in both the azimuth and the elevation planes,and the measured scanning range of each eight-element Rx array is–45°to+45°.The measured maximum effective isotropic radiated power(EIRP)of the eight-element Tx array is 43.2 dBm at 28.0 GHz(considering the saturation point).Furthermore,the measured error vector magnitude(EVM)is less than 3%when 64-quadrature amplitude modulation(QAM)waveforms are used.

Performance analysis of the tight combination of GPS, BDS, GALILEO, and QzsS mixed frequencies signals

With the gradual development and modernization of satellite navigation systems,using observation information from multi-GNss has become one of the hot-spot issues in recent years.Multi-system loose combinations form double-difference observation equations within their respective systems,and the positioning effect is improved.However,the interchangeability and compatible interoperability between global navigation satellite systems(GNSS)cannot be truly realized.At the same time,when the number of visible satellites decreases abruptly,the positioning performance deteriorates sharply.This paper focuses on the GNsS multi-system tight combination relative positioning technique,gives a mathe-matical model of multi-system tight combination relative positioning considering differential inter-system bias(DISB),and analyzes the time-varying characteristics of DISB at overlapping and non-overlapping frequencies among GPS/Galileo,GPS/BDS,and GPS/QZSS in terms of receiver brand,tem-perature,and receiver restart.The GNsS tight combination relative positioning performance is verified by static data from Curtin University and dynamic data measured at Taiyuan University of Technology.The results show that compared with loose combination,the ambiguity-fixed rate increases from 62.18%to 97.60%for static data and from 74.97%to 99.53%for dynamic data when the elevation mask angle is 50°,resulting in a significant improvement in positioning performance.

Map activation of various brain regions using different frequencies of electroacupuncture ST36,utilizing the FosCreER strategy

Objective:Electroacupuncture(EA)is an alternative treatment option for pain.Different frequencies of EA have different painrelieving effects;however,the central mechanism is still not well understood.Methods:The Fos2A-iCreER(TRAP):Ai9 mice were divided into three groups(sham,2 Hz,and 100 Hz).The mice were intraperitoneally injected with 4-hydroxytamoxifen(4-OHT)immediately after EA at Zusanli(ST36)for 30 min to record the activated neurons.One week later,the mice were sacrificed,and the number of TRAP-treated neurons activated by EA in the thalamus,amygdala,cortex,and hypothalamus was determined.Results:In the cortex,2 Hz EA activated more TRAP-treated neurons than 100 Hz EA did in the cingulate cortex area 1(Cg1)and primary somatosensory cortex(S1),and 2 and 100 Hz EAs did not differ from sham EA.TRAP-treated neurons activated by 2 Hz EA were upregulated in the insular cortex(IC)and secondary somatosensory cortex(S2)compared with those activated by 100 Hz and sham EA.In the thalamus,the number of TRAP-treated neurons activated by 2 Hz EA was elevated in the paraventricular thalamic nucleus(PV)compared with those activated by sham EA.In the ventrolateral thalamic nucleus(VL),the number of TRAPtreated neurons activated by 2 Hz EA was significantly upregulated compared with those activated by 100 Hz EA,and sham EA showed no difference compared with 2 or 100 Hz EA.TRAP-treated neurons were more frequently activated in the ventral posterolateral thalamic nucleus(VPL)by 2 Hz EA than by 100 Hz or sham EA.Conclusions:Low-frequency EA ST36 effectively activates neurons in the Cg1,S1,S2,IC,VPL,PV,and VL.The enhanced excitability of the aforementioned nuclei induced by low-frequency EA may be related to its superior efficacy in the treatment of neuropathological pain.

Wave field structure and power coupling features of blue-core helicon plasma driven by various antenna geometries and frequencies

This paper deals with wave propagation and power coupling in blue-core helicon plasma driven by various antennas and frequencies.It is found that compared to non-blue-core mode,for blue-core mode,the wave can propagate in the core region,and it decays sharply outside the core.The power absorption is lower and steeper in radius for blue-core mode.Regarding the effects of antenna geometry for blue-core mode,it shows that half helix antenna yields the strongest wave field and power absorption,while loop antenna yields the lowest.Moreover,near axis,for antennas with m=+1,the wave field increases with axial distance.In the core region,the wave number approaches to a saturation value at much lower frequency for non-blue-core mode compared to blue-core mode.The total loading resistance is much lower for blue-core mode.These findings are valuable to understanding the physics of blue-core helicon discharge and optimizing the experimental performance of blue-core helicon plasma sources for applications such as space propulsion and material treatment.

Experimental investigation of the polarityswitching process with different bipolar ionic liquid thruster operating frequencies

The bipolar ionic liquid thruster employs ionic liquid as a propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC)power source,effectively suppressing electrochemical reaction and ensuring charge neutrality.Determining an optimal AC supply power source frequency is critical for sustained stable thruster operation.This study focuses on the emission characteristics of the ionic liquid thruster under varied AC conditions.The AC power supply was set within the frequency range of 0.5-64 Hz,with eight specific frequency conditions selected for experimentation.The experimental results indicate that the thruster operates steadily within a voltage range of±1470 to±1920 V,with corresponding positive polarity current ranging from 0.41 to 4.91μA and negative polarity current ranging from−0.49 to−4.10μA.During voltage polarity switching,an emission delay occurs,manifested as a prominent peak signal caused by circuit capacitance characteristics and a minor peak signal resulting from liquid droplets.Extended emission test was conducted at 16 Hz,demonstrating approximately 1 h and 50 min of consistent emission before intermittent discharge.These findings underscore the favorable impact of AC conditions within the 8-16 Hz range on the self-neutralization capability of the ionic liquid thruster.

Enriched Constant Elements in the Boundary Element Method for Solving 2D Acoustic Problems at Higher Frequencies

The boundary element method(BEM)is a popular method for solving acoustic wave propagation problems,especially those in exterior domains,owing to its ease in handling radiation conditions at infinity.However,BEM models must meet the requirement of 6–10 elements per wavelength,using the conventional constant,linear,or quadratic elements.Therefore,a large storage size of memory and long solution time are often needed in solving higher-frequency problems.In this work,we propose two new types of enriched elements based on conventional constant boundary elements to improve the computational efficiency of the 2D acoustic BEM.The first one uses a plane wave expansion,which can be used to model scattering problems.The second one uses a special plane wave expansion,which can be used tomodel radiation problems.Five examples are investigated to showthe advantages of the enriched elements.Compared with the conventional constant elements,the new enriched elements can deliver results with the same accuracy and in less computational time.This improvement in the computational efficiency is more evident at higher frequencies(with the nondimensional wave numbers exceeding 100).The paper concludes with the potential of our proposed enriched elements and plans for their further improvement.

Abaca Fiber as a Potential Reinforcer for Acoustic Absorption Material at Middle-High Frequencies

Recently,abacafibers have become the focus of specialized research due to their intriguing characteristics,with their outstanding mechanical properties being a particularly notable.In the conducted study,the abacafibers underwent a preliminary treatment process involving an alkaline solution,which was composed of 0.5%sodium hydroxide(NaOH)and 50%acetic acid(CH3COOH).This process entailed immersing eachfiber in the solution for a period of one hour.This treatment led to a 52.36%reduction in lignin content compared to the levels before treatment,resulting in a dramatic decrease in the full width at half maximum(FWHM)in the XRD spectra from 1.13 to 0.13.This change indicates that thefibers became more crystalline following the treatment.The abacafibers were also characterized using BET(Brunauer Emmett Teller)measurements,which revealed that the aver-age pore length ranged from 33–49 nm and the surface area was between 13–28 m^(2)·g^(-1).The morphology of the abacafiber after alkali an hydrolisis treatment(AFAH)appeared rougher and more uniform.DMA measurements revealed a significant rise in the storage modulus of the singlefiber post-treatment,with dependencies on both frequency and temperature.AFAH exhibited an optimal absorption coefficient ofα=0.9 for frequencies above 2500 Hz.The combined effect of alkalization and hydrolyzation treatments,while resulting in an enhancement in the mechanical properties of thefibers,also reduced high-intensity noise produced by sources such as machin-ery,aircraft takeoffs and landings,etc.,across a broader working frequency range.

A 37 GHz Millimeter-Wave Antenna Array for 5G Communication Terminals

This work presents,design and specific absorption rate(SAR)analysis of a 37GHz antenna,for 5th Generation(5G)applications.The proposed antenna comprises of 4-elements of rectangular patch and an even distribution.The radiating element is composed of copper material supported by Rogers RT5880 substrate of thickness,0.254 mm,dielectric constant(εr),2.2,and loss tangent,0.0009.The 4-elements array antenna is compact in size with a dimension of 8mm×20mm in length and width.The radiating patch is excited with a 50 ohms connector i.e.,K-type.The antenna resonates in the frequency band of 37 GHz,that covers the 5G applications.The antenna behavior is studied both in free space and in the proximity of the human body.Three models of the human body,i.e.,belly,hand,and head(contain skin,fat,muscles,and bone)are considered for on-body simulations.At resonant frequency,the antenna gives a boresight gain of 11.6 dB.The antenna radiates efficiently with a radiated efficiency of more than 90%.Also,it is observed that the antenna detunes to the lowest in the proximity of the human body,but still a good impedance matching is achieved considering the−10 dB criteria.Moreover,SAR is also being presented.The safe limit of 2 W/kg for any 10 g of biological tissue,specified by the European International Electro Technical Commission(IEC)has been considered.The calculated values of SAR for human body models,i.e.,belly,hand and head are 1.82,1.81 and 1.09 W/kg,respectively.The SAR values are less than the international recommendations for the three models.Furthermore,the simulated and measured results of the antenna are in close agreement,which makes it,a potential candidate for the fifth-generation smart phones and other handheld devices.

A Low Power,High Sensitivity SiGe HBT Static Frequency Divider up to 90 GHz for Millimeter-Wave Application

A layout and connection optimization for static frequency divider is presented. The layout optimization provides a new circle topology transistors placement and reasonable connection structure, which reduces the parasitic effectively and enables self-oscillation frequency enhancement. Besides, bandwidth enhancement techniques based on a center-tap capacitor in input balun design and inductive peaking in latch design are adopted to improve further high frequency performance with low power consumption. As a proof of concept, design of a divide-by-2 static frequency divider in 0.13 μm SiGe BiCMOS technology is reported. With single-ended input clock signal, the divider is measured to be operated from 40 to 90 GHz. Phase noise measurements of a 90 GHz input clock signal indicate ideal behavior with no measurable noise contribution from the divider. The divider followed by a buffer that can deliver more than-10 dBm output power, which is sufficient to drive succeeding stage. To the author's knowledge, the divider exhibits a competitive power dissipation and the highest FOM among silicon based frequency dividers that operating higher than 70 GHz.

High-Precision Doppler Frequency Estimation Based Positioning Using OTFS Modulations by Red and Blue Frequency Shift Discriminator

Orthogonal Time Frequency and Space(OTFS) modulation is expected to provide high-speed and ultra-reliable communications for emerging mobile applications, including low-orbit satellite communications. Using the Doppler frequency for positioning is a promising research direction on communication and navigation integration. To tackle the high Doppler frequency and low signal-to-noise ratio(SNR) in satellite communication, this paper proposes a Red and Blue Frequency Shift Discriminator(RBFSD) based on the pseudo-noise(PN) sequence.The paper derives that the cross-correlation function on the Doppler domain exhibits the characteristic of a Sinc function. Therefore, it applies modulation onto the Delay-Doppler domain using PN sequence and adjusts Doppler frequency estimation by red-shifting or blue-shifting. Simulation results show that the performance of Doppler frequency estimation is close to the Cramér-Rao Lower Bound when the SNR is greater than -15dB. The proposed algorithm is about 1/D times less complex than the existing PN pilot sequence algorithm, where D is the resolution of the fractional Doppler.

Coherent optical frequency transfer via 972-km fiber link

We demonstrate coherent optical frequency dissemination over a distance of 972 km by cascading two spans where the phase noise is passively compensated for.Instead of employing a phase discriminator and a phase locking loop in the conventional active phase control scheme,the passive phase noise cancellation is realized by feeding double-trip beat-note frequency to the driver of the acoustic optical modulator at the local site.This passive scheme exhibits fine robustness and reliability,making it suitable for long-distance and noisy fiber links.An optical regeneration station is used in the link for signal amplification and cascaded transmission.The phase noise cancellation and transfer instability of the 972-km link is investigated,and transfer instability of 1.1×10^(-19)at 10^(4)s is achieved.This work provides a promising method for realizing optical frequency distribution over thousands of kilometers by using fiber links.

Research on the Different Frequencies of Transcutaneous Electrical Acupoint Stimulation for Postpartum Pelvic Girdle Pain

Objective:To observe the clinical effect of different frequencies of transcutaneous electrical acupoint stimulation in treating postpartum pelvic girdle pain and promoting postpartum rehabilitation.Methods:From January to September 2022,300 patients with pelvic girdle pain after spontaneous delivery in a hospital in Shaanxi Province were selected and randomly divided into three groups,low frequency,high frequency,and alternating frequency,with 100 cases in each group.In addition to routine postpartum care and psychological counseling,the three groups received transcutaneous electrical acupoint stimulation at low-frequency(2 Hz,)high-frequency(100 Hz),and alternating frequency(2/100 Hz),respectively.The differences in initial pain,pain scores before and after treatment,satisfaction with analgesic effect,and postpartum rehabilitation effect were evaluated among the three groups of patients.Results:There was a significant correlation between maternal age and postpartum pelvic girdle pain(P<0.001),but no correlation was observed between newborn birth weight and postpartum pelvic girdle pain(P>0.05).After 1d/2d of treatment,the pain scores and rehabilitation effect of patients in the alternating-frequency group and low-frequency group were significantly better than those in the high-frequency group,and the postpartum curative effect of patients in the alternating-frequency group was the best,followed by the low-frequency group,and the high-frequency group;the differences were statistically significant(P<0.001).Among the three groups,the alternating-frequency group had the highest satisfaction with the analgesic effect and the highest rate of selecting the same analgesic regimen the next time;the differences were statistically significant(P<0.001).Conclusion:Transcutaneous electrical acupoint stimulation at different frequencies is safe and effective in treating postpartum pelvic girdle pain and beneficial to postpartum rehabilitation.Sparse-dense wave stimulation is effective in treating postpartum pelvic girdle pain.It has the best effect in promoting postpartum rehabilitation and the highest patient satisfaction.Therefore,its application in clinical practice is highly recommended.

Transition frequencies between 2S and 2P states of lithium-like ions

The Schrödinger equation for the 2S and 2P states of the lithium-like ions Z=5–7,9–10 is solved by using the Rayleigh-Ritz variational method in Hylleraas coordinates.The leading-order relativistic and QED corrections are calculated perturbatively and higher-order corrections are estimated.The transition frequencies between the 2S_(1/2)and 2P_(J)(J=1/2,3/2)states are determined and compared with experimental and other theoretical results.Specifically,isotope shifts are also calculated for B^(2+).

Contribution for Efficient Planning of Millimeter Wave Frequencies: Case of the 80 GHz E-Band for High-Speed Broadband Transmissions

Due to the very high demand for Internet data capacity from mobile and fixed customers as well as the saturation of conventional frequency bands by numerous services, many countries have opened the E band, for broadcasting services. E-band involves the creation of a significant number of links in a given area. The present work addressed the problem that arises in the context of transmission is that of assigning the frequencies of this band to these multiple transmission links. The aim of this work is to study and plan the radio links of the 80 GHz frequency and to implement them in a tool in order to define an optimal distribution on the telecommunications network by guaranteeing maximum flow of data traffic while minimizing the interference. The contribution of this work is part of its unique subject: the planning of E-band frequencies for improving the quality of service of transmission in the network of telecommunications operators. Also, it intends to contribute to the resolution of unsatisfied situations of poor planning of E-band radio frequencies in telecommunications networks. With the aim of opening several opportunities for alternative high-speed data transport solutions, our work has helped prove that E-band transmission links are very efficient with capacities in the gigabyte range.

Non-LOS target localization via millimeter-wave automotive radar

This paper considers the non-line-of-sight(NLOS)vehicle localization problem by using millimeter-wave(MMW)automotive radar.Several preliminary attempts for NLOS vehicle detection are carried out and achieve good results.Firstly,an electromagnetic(EM)wave NLOS multipath propagation model for vehicle scene is established.Subsequently,with the help of available multipath echoes,a complete NLOS vehicle localiza-tion algorithm is proposed.Finally,simulation and experimental results validate the effectiveness of the established EM wave propagation model and the proposed NLOS vehicle localization algorithm.

Ultrafast dynamics of femtosecond laser-induced high spatial frequency periodic structures on silicon surfaces

Femtosecond laser-induced periodic surface structures(LIPSS)have been extensively studied over the past few decades.In particular,the period and groove width of high-spatial-frequency LIPSS(HSFL)is much smaller than the diffraction limit,making it a useful method for efficient nanomanufacturing.However,compared with the low-spatial-frequency LIPSS(LSFL),the structure size of the HSFL is smaller,and it is more easily submerged.Therefore,the formation mechanism of HSFL is complex and has always been a research hotspot in this field.In this study,regular LSFL with a period of 760 nm was fabricated in advance on a silicon surface with two-beam interference using an 800 nm,50 fs femtosecond laser.The ultrafast dynamics of HSFL formation on the silicon surface of prefabricated LSFL under single femtosecond laser pulse irradiation were observed and analyzed for the first time using collinear pump-probe imaging method.In general,the evolution of the surface structure undergoes five sequential stages:the LSFL begins to split,becomes uniform HSFL,degenerates into an irregular LSFL,undergoes secondary splitting into a weakly uniform HSFL,and evolves into an irregular LSFL or is submerged.The results indicate that the local enhancement of the submerged nanocavity,or the nanoplasma,in the prefabricated LSFL ridge led to the splitting of the LSFL,and the thermodynamic effect drove the homogenization of the splitting LSFL,which evolved into HSFL.