Showing papers by "Jun-Fa Mao published in 2020"

Half-Mode Substrate Integrated Waveguide Dispersion Tailoring Using 2.5-D Spoof Surface Plasmon Polaritons Structure

Abstract: In this article, a half-mode substrate integrated waveguide (HMSIW) combined with 2.5-D spoof surface plasmon polaritons (SPPs) structure is proposed to tailor the dispersion features and cutoff frequency of the HMSIW. The proposed HMSIW-SPP structure has a smaller longitudinal dimension since the dispersion of the proposed structure can be tailored by adjusting the geometric parameters of the 2.5-D spoof SPP arbitrary. Simultaneously, the proposed structure has a smaller lateral width than that of the classical HMSIW because the 2.5-D spoof SPP introduces extra capacitance in the waveguide. Moreover, an equivalent circuit model is proposed and used to analyze the design principles. The structure exhibiting the cutoff frequency of 6.0 GHz is designed and fabricated under the printed circuit board process. Measurement and simulation results show that the proposed HMSIW-SPP structure decreases the longitudinal dimension by more than 50% and the lateral width by 25% without sacrificing its transmission performance. Due to the reduced cutoff frequency and effective wavelength, the proposed structure enables extreme miniaturization and can be applied in the design of miniaturized microwave circuits.

Heatsink Antenna Array for Millimeter-Wave Applications

Abstract: In this communication, a novel fin-shaped heatsink antenna array is designed and fabricated by 3-D printing and low-temperature cofired ceramic (LTCC) technologies. Its structure consists of 16 rectangular air cavities in the bottom base, which are used to form the open-ended rectangular waveguide antennas. Combined with the waveguide and metallic fins, a step-profiled horn is formed as the antenna element, which further enhances the radiation performance. This heatsink antenna array is soldered on an LTCC substrate and the feeding network is realized by the substrate integrated waveguides (SIWs) with numerous metallic vias. These metallic vias inherently provide an effective path for transferring the heat from chips to the heatsink. The simulated performance of this heatsink antenna array is in good agreement with the measured one. The measured broadside gain is 18.1 dBi at 60 GHz, and the 10 dB relative impedance bandwidth is 11.7%.

Low-Profile Broadband Plasma Antenna for Naval Communications in VHF and UHF Bands

Abstract: This article presents a broadband reconfigurable very-high-frequency/ultrahigh-frequency (VHF/UHF) plasma antenna with omnidirectional features for naval communications. A copper element, engineered as an inverted-discone antenna, operates at a high frequency of 100–512 MHz. We loaded eight similar plasma tubes above the discone as metal bars, which enable radiations at 30–100 MHz frequency. The antenna height over a ground plane is $\lambda $ /10 at the lowest band. By applying the electrically tuned plasma, we achieved reconfiguration and obtained an average of 9.5 dB radar cross section (RCS) reduction. We fabricated Butterworth low-pass filter (LPF) and high-pass filter (HPF) to isolate 13.56 MHz radio frequency (RF) signal which is used to activate plasma. Moreover, we designed a lumped-distributed impedance matching network at the feeding position to improve transmission. The measurement results show that the VSWR of the antenna is less than 3 over a 17:1 bandwidth, and the azimuth gain of the antenna is greater than −5 dB. Besides, an unmanned aerial vehicle (UAV) system is proposed to measure the radiation patterns. The results confirm that the proposed antenna is a viable candidate for naval communications with ships and ground base stations.

Crosstalk Noise Suppression Between Single and Differential Transmission Lines Using Spoof Surface Plasmon Polaritons

Abstract: Crosstalk noise suppression is a crux in the high-speed integrated circuit design, which requires weak-coupling between transmission lines (TLs) over a wide band. To overcome the difficulty, this article presents a novel method to suppress the broadband crosstalk noise between a single TL and the differential pair based on spoof surface plasmon polaritons (SPPs). Due to the subwavelength feature of spoof SPP TLs, a natural mode mismatching between the spoof SPP TL and conventional microstrip (MS) brings a broadband suppression of near-field coupling. In order to verify the crosstalk suppression effect, four different kinds of prototypes are discussed and compared. The simulated and measured results in the frequency domain and time domain demonstrate that the proposed scheme achieves more than 83% far-end noise peak suppression than the traditional MS technology by replacing the single MS TL to the spoof SPP TL. Accordingly, the time-domain crosstalk noise is significantly suppressed without any extra costs, demonstrating its potential applications in ultracompact high-speed integrated circuits.

Fast Analytic Electromigration Analysis for General Multisegment Interconnect Wires

Abstract: Electromigration (EM) is considered to be one of the most important reliability issues for current and future ICs in 10-nm technology and below. In this article, we propose a fast analytic solution to compute the stress evolution in the confined multisegment interconnect wires. The new method, called the accelerated separation of variables (ASOV) method, aims to find the analytic solutions of the partial differential equations of stress in confined interconnect metals based on the SOV method. It offers several improvements over the existing plain SOV-based method. First, we show that the accuracy of the solution depends on the structure of the interconnects. As a result, the number of required eigenvalues is structure and problem dependent, instead of fixed numbers used by the existing SOV method. Second, for the straight line multisegment and star-structured multiterminal interconnects, analytical expressions are formulated to calculate the eigenvalues directly instead of using numerical methods as in the existing SOV method. Third, we propose a linear Gaussian elimination (GE) algorithm by exploiting the banded structure with the serrated-edge form of the transcendental matrix, which can significantly speed up GE process, and is the key computing step in the SOV-based solution framework. Fourth, instead of using the simple bisection search, we propose to use an enhanced determinant-based secant iterative method to find the eigenvalues of the transcendental matrix. Numerical results show that a good agreement is achieved between analytical and numerical results on two special cases, and the resulting algorithm can lead to 3–5X speedup over the existing plain SOV-based solution on a number of multisegment interconnects benchmarks.

Noncontact High-Linear Motion Sensing Based on A Modified Differentiate and Cross-Multiply Algorithm

Abstract: The interferometric radar sensor can wirelessly detect the relative displacement motions, owing to its inherent nature of high sensitivity to the moving objects. To overcome the phase ambiguity and discontinuity caused by non-linear phase modulation, approaches such as differentiate and cross-multiply (DACM) were proposed for linear demodulation of the vibration motions. However, the existing DACM algorithm is strongly dependent on the calibration of I/Q output signals, resulting in low tolerance to noise and inaccuracy in detecting motions of large linear displacement. Based on the differentiation and the geometrical theorem of the trigonometric functions, this paper proposes a modified DACM algorithm with simplified expression but much improved performance for high-linear motion detection. Theoretical analysis was presented to introduce the proposed algorithm. Both simulation and experimental results demonstrate that the proposed algorithm is not only free from phase ambiguity, but also superior in several aspects: the stability under a signal to noise ratio (SNR) of 25 dB has been improved by 9 dB and the linearity of measuring large displacement motion has been improved by 32 dB, comparing to the existing DACM algorithm. Moreover, the simplified expression would greatly reduce the computational resources needed for linear phase demodulation.

A Novel Automatically Designed EBG Structure by Improved GA for Ultrawideband SSN Mitigation of System in Package

Abstract: In this article, a novel automatically designed electromagnetic bandgap (EBG) structure is presented to prohibit the simultaneous switching noise (SSN) propagation of a system in package. The tool employed for the automatic EBG design is the improved genetic algorithm (GA), which has the advantages of rapid convergence and high precision by combining several improvements reasonably. Meanwhile, the equivalent circuit model and the dispersion diagram of the proposed structure are established to interpret the electromagnetic characteristics of the designed power distribution network (PDN). By removing some patches in a specific area determined by the GA, the surface impedance of PDN can be increased to reduce the SSN coupling. The SSN transmission can be suppressed from 0.37 to 20 GHz at a mitigation level of −50 dB. The measured results agree well with the simulated ones.

Orbital angular momentum radiator multiplexing electromagnetic waves in free space.

Abstract: Orbital angular momentum (OAM) modes of electromagnetic (EM) waves have been extensively studied to obtain more than two independent channels at a single frequency. Thus far, however, multiple radiators have been used to achieve this goal in wireless communications. For the first time, a single radiator was designed to simultaneously transmit three OAM waves in free space at the same frequency. Our design makes use of the radiating resonant modes of a dielectric resonator antenna (DRA). For demonstration, a wireless communication system consisting of a pair of transmitting and receiving OAM DRAs was setup and measured. Three EM waves carrying three different signals were transmitted and received successfully, increasing the system throughput without requiring any complex signal processing algorithms. It confirms that a single radiator can wirelessly transmit more than two independent EM waves at a single frequency by using multi-OAM modes. The work is useful for the future high-speed wireless communication systems.

Analysis on a 77 GHz MIMO Radar for Touchless Gesture Sensing

Abstract: This letter presents a novel analysis on a millimeter-wave 77 GHz multiple-input multiple-output (MIMO) radar with virtual antenna array for touchless gesture sensing for human-computer interaction. The virtual array allows fewer receiving channels to achieve higher spatial resolution, which facilitates the integration of radar technology into compact devices. The theoretical analysis and working principles were introduced. Compared to the conventional analysis of MIMO radar, the analytical model proposed in this letter takes the radiation pattern of each antenna into consideration and reveals the nature of virtual antenna array, e.g., the change of the phase factor. Besides, the radiation pattern of each virtual antenna is also obtained, and two equivalent virtual array models decomposed by the analytical model are also discussed. A 77 GHz 2 × 2 MIMO radar system was designed with a maximum scanning bandwidth of 5 GHz and was employed to validate the application of gesture sensing. Based on frequency-modulated continuous-wave with 4 GHz bandwidth and pulse repetition time of 6 ms, a hand's moving gestures were successfully captured with submillimeter accuracy. Presence detection was also experimentally carried out to detect the approach of the subject person.

Efficient Transient Thermal Simulation of ICs and Packages With Laguerre-Based Finite-Element Method

Abstract: In this article, an efficient approach based on Laguerre-based finite-element method (LBFEM) is proposed for transient thermal simulation of integrated circuits (ICs) and packages. The unconditionally stable marching-on-in-order scheme is developed by the weighted Laguerre polynomials and Galerkin testing procedure. In order to handle complicated ICs and packages, the finite-element method (FEM) is employed for spatial discretization and to obtain the Laguerre coefficients. The treatment of different kinds of boundary conditions is also discussed in detail. The accuracy and efficiency of the proposed method are demonstrated by numerical examples.

Design and Fabrication of Patch Antenna Array on Quartz Glass Substrate at 146 GHz

Abstract: In this paper, the printed D-Band patch antenna and 1×4 array antenna are designed on the quartz glass substrate, which are suitable for millimeter wave applications. The central frequency of the antenna array is designed at 146 GHz. Because there are no metal vias in the quartz glass substrate, the gold belt is utilized to connect the signal ground on the top surface with the antenna ground on the bottom of substrate. The relative position of the gold belt affects the resonant frequency of the antenna. The prototypes of the antennas are successfully fabricated and measured. The measured gain of patch antenna unit and antenna array are 6.6 dBi and 11.4 dBi, respectively, at 146 GHz. The S11 below -10 dB bandwidth are about 6.4% and 5.9%, respectively.

A New Compact Power Divider Based on Capacitor Central Loaded Coupled Microstrip Line

Abstract: A new power divider is proposed with a compact size. In 50- $\Omega $ systems, impedance transformation is of great importance for power dividers. Coupled microstrip lines with capacitor loaded and two short-circuited ports are introduced to properly transform impedance and increase degrees of freedom in power divider designs. Image impedance and image transfer constant of coupled microstrip lines with capacitor loaded are derived. The main structural parameters of the power divider are calculated accordingly. A special design procedure is illustrated for the proposed power divider with the capacitor loaded, which is implemented on a printed circuit board. A good agreement between the simulated model and the fabricated sample is observed, which demonstrates the validity of the proposed circuit model and the design scenario.

High Performance V2X Antennas Designed in Integrated Shark-fin Environment

Abstract: A new high performance two-element V2X antenna array is presented, which is interspersed between two LTE antennas and designed in shark-fin environment. By using the specific designed lines and the closely EM coupling features, the desired current distributions in the element are achieved. Its high performance, with 10dB impedance bandwidth of 5% (5.7-6.0GHz), port isolation of 23 dB under the gain of 5.8dBi in elevation plane and the variation less than 5dBi in azimuthal plane, are finally verified by simulations and measurements, showing the great potential applications in automobile wireless communications.

Silent Speech Recognition based on Short-Range Millimeter-Wave Sensing

Abstract: A new silent-speech recognition technique based on a compact custom-designed 120 GHz interferometric radar system is proposed. The millimeter-wave 120 GHz makes it possible to precisely track the fine displacement of the mouth movement, which is strictly related to the speech activities. To overcome the phase ambiguity in millimeter-wave non-linear phase modulation, a novel algorithm based on trigonometric transform is proposed to linearly reconstruct the phase information of the speech. The proposed technique carries the merits of contact-free, high penetrability and high precision. Experiments have been performed in the office environment and the results show that the proposed technique performs well in sensing the precise silent-speech commands for both words and sentences. The specific patterns existing in each command provide foundation for silent-speech recognition.

A Novel Design of Compact Out-of-Phase Power Divider With Arbitrary Ratio

Abstract: In a conventional power divider, power dividing network and isolation network are usually independent of each other. To reduce the size of out-of-phase power divider with arbitrary power ratio, coupled microstrip lines are proposed to facilitate power dividing and isolation of a power divider simultaneously in this article. Formulations have been derived for the proposed out-of-phase power divider with arbitrary ratio. Two compact power dividers are implemented on the printed circuit board (PCB) with power ratio $k^{2} = 9$ and $k^{2} = 1000$ . It can be observed that there is a satisfactory agreement between the simulated and measured results.

A Compact Ridged Substrate Integrated Coaxial Line

Abstract: Substrate integrated coaxial line (SICL) has been widely used for high frequency interconnects. In this paper, a ridged substrate integrated coaxial line (RSICL) is proposed. It has similar structure to the SICL but has two ridges on both sides of the inner conductor. The proposed RSICL is a quasi-shielding structure which can support the transverse electromagnetic (TEM) mode. Moreover, the introduction of ridges into SICL can significantly minimize the interconnect size. The dominant mode and higher-order modes, the characteristic impedance and the propagation constants of the RSICL are analyzed based on the full-wave simulation software. Compared with the SICL, the RSICL can reduce the width of the internal and external conductors by 22.5% and 10%, respectively. Besides, the dominant mode bandwidth of the RSICL is 11 % wider than that of the SICL.

A Compact 2-D Stochastic FDTD Method for Uncertainty Analysis in Superconducting Transmission Lines

Abstract: In this article, a stochastic finite-difference time-domain (S-FDTD) method is proposed for analyzing the influence of physical size uncertainty on the time-domain response of superconducting transmission lines The formulations of the proposed method are, in detail, derived with the two-fluid model and London equation A typical superconducting microstrip line is simulated to verify the effectiveness of the proposed algorithm Compared with the Monte Carlo simulation, the proposed method has the same accuracy but much higher efficiency The computation time of the proposed S-FDTD method is only about 3% of that of the Monte Carlo simulation Therefore, the proposed method shows a promising prospect on predicting the variability in transmission line's performance caused by variation in superconducting manufacturing

Suppressing Coupling and Stationary Clutters in FMCW Radars with Temporal Filtering

Abstract: In this paper, a novel signal processing technique based on temporal filtering is proposed to alleviate the coupling between the transmitting (TX) and receiving (RX) channels in frequency-modulated continuous-wave (FMCW) radars It works by subtracting the target beat signal with the reference beat signal in the absence of the target being detected Moreover, the proposed temporal filtering technique is also promising to eliminate static clutters A spectrum-based alignment algorithm was developed to align the target beat signal with the reference signal The working principle and theory were introduced in details The gesture sensing experiments are carried out to validate the proposed technique The experimental results show that the TX-RX coupling was suppressed by about 20 dB With the proposed technique, the ranging accuracy is also significantly improved by suppressing the mean square error (MSE) by 125 dB

A New Structure for Broadband Transition Between Differential Stripline and Differential GCPW

Abstract: In this paper, a new structure for broadband transition between differential stripline (DSL) and differential grounded coplanar waveguide (DGCPW) is presented for probe test and high-speed data transmission application. The proposed structure is designed under low temperature co-fired ceramic (LTCC) technology. A stepwise structure in the transition is utilized to eliminate additional vias on signal traces. Low insertion loss and low reflection up to 60 GHz are demonstrated by full-wave simulation.

Miniaturization of Grid Array Antenna Using Spoof Surface Plasmon Po-laritons

Abstract: This paper presents a design of miniaturized grid array antenna (GAA) using spoof surface plasmon polaritons (SPPs). The miniaturization is achieved by loading periodic grooves on the long sides of traditional GAA, with an aera-reduction factor of 36.3%. The matching stubs are introduced to improve impedance bandwidth. From the simulated results, the proposed antenna manages to support a -10 dB impedance bandwidth of 12.5%, ranging from 25.82 GHz to 29.26 GHz, with the maximum realized gain of 13.56 dBi. The effective size of the proposed antenna is 1.08λ0×2.07λ 0 ×0.07λ 0 , where λ 0 is the vacuum wavelength at 28 GHz.

Substrate Integrated Waveguides Slot Antenna Array with Heatsink Enclosed

Abstract: In this paper, a substrate integrated waveguide (SIW) slot antenna array combined with fin-shaped heatsink is designed. It consists of four 1×8 SIW slot antenna elements. The heatsink structure enclosed in the design enhances heat dissipation capability of the antenna array while maintaining the radiation performance of the original structure. The simulated −10 dB impedance bandwidth of the antenna array with and without heatsink are 6.5% and 6.4%, respectively. In addition, the realized gain are 19.16 dBi and 18.04 dBi at 28 GHz, respectively.

Transient Coanalysis of Multicoupled Passive Transmission Lines and Josephson Junctions Based on FDTD

Abstract: With the development of rapid single-flux-quantum (RSFQ) circuits, signal integrity issues of interconnects, such as signal distortion and crosstalk, become critical. Josephson junctions, as driver and receiver of interconnects, also affect signal integrity. Hence, it is significant to coanalyze time-domain responses of multicoupled passive transmission lines (PTLs) and Josephson junctions in RSFQ circuits. In this article, an accurate numerical method based on finite-difference time-domain (FDTD) is proposed to coanalyze multicoupled PTLs and Josephson junctions. The FDTD method is used to solve the telegraph equations of PTLs, and an iteration algorithm based on the contractive mapping theorem is proposed to solve the nonlinear equations generated by the Josephson junctions. In addition, the existence and uniqueness conditions of the nonlinear equations are also provided. The numerical and simulation results show that the proposed coanalysis method has the same accuracy as but higher efficiency than WRspice.

Mode Analysis of Rectangular Polymer Microwave Fibers Based on Finite-Difference Frequency-Domain Method

Abstract: The polymer microwave fiber (PMF) is an attractive millimeter-wave (mm-Wave) communication link since it is high-rate, low-loss, cheap and flexible. In this paper, the propagation modes of the rectangular PMF are analyzed based on the compact two-dimensional (2-D) finite-difference frequency-domain (FDFD) method. Results show that the electric field of the dominant mode of PMF becomes more and more concentrated inside the PMF with increasing frequency. The high-order modes and their dispersion relations are also calculated. The calculated propagation constants are compared with that from the approximate analytical method to verify the accuracy of the compact 2-D FDFD method.

Transmission Loss Analysis of Grounded and Ungrounded SSPP Transmission Lines

Abstract: In this paper, the transmission losses of grounded and undergrounded spoof surface plasmon polariton (SSPP) transmission lines (TLs) are investigated over a wide frequency range To overcome the effects of transition structures of SSPP transmission lines, the multiline method is utilized for the de-embedding purpose Attenuation constants of grounded SSPP (G-SSPP) lines, ungrounded SSPP (U-SSPP) lines and traditional microstrip (MS) lines in the same size are compared in detail The impact of dielectric loss tangent on attenuation performance is also discussed

Microstrip Memristive Switch and Its Applications to RF Devices

Abstract: In order to achieve the characteristics of non-volatility and low power consumption, a memristive RF switch is proposed on a microstrip line with good performance up to 5 GHz. Based on Conductive bridging random access memory (CBRAM) technology, this switch uses metal-insulator-metal (MIM) structure, Copper/Nafion/Au specifically. Then, a reconfigurable bandpass filter is designed at 0.91 and 1.0 GHz with the ON-/OFF-state memristive RF switches, respectively. A 180° reflective type phase shifter is designed at 5 GHz with the microstrip memristive RF switches. These memristive RF devices may push the envelope for intelligent RF systems.

A Fast and Accurate Method for Bond Wires Inductances Extraction Based on Machine Learning Strategy

Abstract: This paper presents a fast and precise method for bond wire inductances extraction based on machine learning strategy. The dataset for training is collected from electromagnetic (EA) simulator and equivalent circuit theory, with the trained model, the self inductances and mutual inductances of bond wires can be accurately extracted only in dependence on their geometric dimensions. Random testing samples are used to verify the proposed method and the results show a tiny discrepancy less than 1% between the real and the predicted values up to 200 GHz. The proposed method will save a lot of time in bond wires inductances analysis and the overall wire bond interconnection design.

Mutual Coupling Analysis of High-Directivity Stacked Patch Array for 77 GHz MIMO Radar

Abstract: A four-channel antenna array is designed at 77 GHz for the MIMO radar application. Parasitic patches are adopted to enhance the directivity but at the cost of distorted radiation pattern in the array and increased mutual coupling among channels. The maximum coupling coefficient between adjacent channels is −18.7 dB at 76.7 GHz, over 10 dB higher than that of an array without parasitic patches. The mechanism of deterioration is discussed by comparing different applications of stacked patches.

An Efficient Compact 2-D WLP-FDTD Method for Plastic Rectangular Waveguides

Abstract: An efficient compact two-dimensional (2-D) finite-difference time-domain method with weighted Laguerre polynomials (WLP-FDTD) for plastic rectangular waveguides is proposed. A typical plastic rectangular waveguide is simulated by both the 2-D WLP-FDTD method and the conventional 2-D FDTD method. Since the compact 2-D WLP-FDTD method is without the restriction of the Courant–Friedrichs–Lewy (CFL) condition, it is more efficient than the 2-D FDTD method.

Testing Method of a Millimeter-Wave/THz Far-Field Antenna Measurement Setup

Abstract: This paper introduces the testing method of a millimeter-wave far-field antenna measurement setup in our lab. First, a brief introduction on how the signal travels and transforms in the devices is given. Then, the testing processes and the method to measure antennas’ impedance and gain pattern is revealed. Finally, a testing example is shown to validate the measurement capability. This paper is convinced to enrich the information about our setup to the research community and provide useful reference in millimeter-wave antenna measurements.