Suppression Of Higher Order Harmonics Research Articles

An Asymmetrical Dual Quasi-Z-Source Based 7-Level Inverter for PV Applications

This paper presents a new single-stage quasi-z-source (qZS) based power converter for Photovoltaic (PV) applications. This seamless topology is obtained by the fusion of two quasi-z-source networks with a 7-level cascaded multilevel inverter (MLI). The proposed converter requires fewer passive components and power switching devices compared to the seven-level topologies with impedance and quasi-impedance sources, reported in the literature. The proposed modulation technique achieves the required level of voltage boosting using the qZS networks while synthesizing seven levels in the output voltage waveform. While the proposed power converter can regulate the output voltage in the standalone mode, it can inject active power into the grid at Unity power factor (UPF) in the grid-connected mode of operation. This paper also aims to mitigate the leakage current, which is one of the major issues in transformerless PV inverters, by reducing the magnitude of voltage transitions in the parasitic capacitor and the suppression of higher-order harmonics in the ground leakage current. The steady-state and the dynamic performances of the proposed power converter during grid-connected mode of operation is assessed with simulation studies and are validated with experimental results.

Multi-Band Power Amplifier Module with Back-Off Efficiency Improvement using Ultra-Compact 3D Vertical Stack Multi-Chip Package for Cellular Handsets.

A highly integrated multi-mode multi-band (MMMB) power amplifier module (PAM) using hybrid bulk complementary metal oxide semiconductor (CMOS), gallium arsenide (GaAs) heterojunction bipolar transistor (HBT), and silicon-on-insulator (SOI) technologies for low band (LB, 824-915 MHz) and high band (HB, 1710-1980 MHz) is proposed. The hybrid MMMB PAM integrates a bulk CMOS controller die, a GaAs HBT power amplifier (PA) die and a SOI switch die on a six-layer laminate. To simultaneously obtain both highly efficient and highly linear characteristics over a wide range of input power levels, a parallel dual-chain PA strategy has been adopted to provide vary bias current and gain for low-power mode (LPM) and high-power mode (HPM) operation. Additionally, a broadband two-section low-pass output matching network design based on the suppression of high-order harmonics is proposed for enhanced efficiency and linearity. In order to achieve further miniaturization, a three-dimensional (3D) die stack multi-chip module (MCM) packaging structure, where the presented CMOS controller die is stacked vertically on the GaAs HBT PA die, is implemented. The measurement results show that the fabricated MMMB PAM achieves 26.1-27 dB of power gains and 38-38.4% of PAEs at an output power (Pout) of 28 dBm in the HPM, and 20.4-20.9 dB of power gains and 12.4-13.8% of PAEs at Pout of 17 dBm in the LPM over LB. For HB, power gains of 24.3-26.7 dB while maintaining PAEs of 38.2-39.9% at Pout of 28 dBm, and power gains of 15.9-17.5 dB while maintaining PAEs of 12.3-12.8% at Pout of 17 dBm are realized in the HPM and LPM, respectively. The fabricated PAM covering five frequency bands and operating at two power modes only occupies a 5 × 3.5 mm2 area. To the best of the authors' knowledge, this work is the first demonstration of a MMMB PAM adopting an ultra-compact 3D vertical stack MCM package with favorable RF performance.

New Design Approach of a “2.4 GHz” Slotted Rectangular Patch Antenna with a Wideband Harmonic Suppression

The designing of an antenna with a wideband harmonic suppression will lead to enhance the overall antenna performance efficiency as well as neglecting electromagnetic noises. A “defective ground superimposing” or a Y-slot construct confederated with a ring hopefully meets an effective approach that is exploited in removing high level of harmonics in the design process. A “2.4 GHz” rectangular U-slot microstrip patch antenna with an active antenna radiators and harmonic suppression grid has been presented. The paper focuses on the geometrical of active integration antennas to achieve efficient filtering and easy attenuation of unwanted harmonics. Further, an embedded empirical antenna with a high-order harmonic suppression has been suggested. This is followed by a “complementary opening recoiled construct cell”. The proposed approach was developed to control the antenna harmonics at center frequency of " $$2.4 \;{\text{GHz}}$$ ." The simulation sketches show that the reflection coefficient of multiple harmonics had an effective suppression up to 3.2 dB without any effect on the resonant frequency. The radiation patterns at high suppression levels of harmonics are within the range (13.92–15.2 dB) for both E-plane and H-plane. Further, the designed antenna bandwidth at the resonant frequency is $$\left( {85\;{\text{MHz}}} \right)$$ . Finally, the proposed antenna with $${\text{DGS}}$$ had return losses and antenna gain of $$\left( { - 23.15 \;{\text{dB}};\;8.25\;{\text{dB}}} \right),$$ respectively.

Broadband circular polarized patch antenna with harmonic suppression

Background/Objectives: To develop Circular Polarized (CP) patch antenna with improved bandwidth and harmonic suppression for RF energy harvesting system. Methods/Statistical analysis: A l /4 resonator is introduced and coupled in proximity to the radiating patch for bandwidth enhancement and high order harmonic suppression. Compared with other dual-resonance patch antennas, the proposed antenna has attractive low-profile property and simple structure. The CP can be achieved by putting arc shape slits at edge of circular patch. The structure, working principle and results we are described. Findings/Applications: The operating bandwidth is from 1.68 GHz to 2.95 GHz (52.91%) with a reflection coefficient less than -10 dB with Axial Ratio bandwidth of 550MHz (2.21 GHz -2.76 GHz) while harmonic suppression over wide frequency range from 1 to 12 GHz is achieved. The experimental and simulated results is good matching except some slight variation. Novelty/Applications: New techniques for both bandwidth enhanced and harmonic suppression and up to 4th higher order harmonics has been suppressed. Proposed structure offers wideband CP Antenna with harmonic suppression. Keywords: RF energy harvesting; microstrip patch antenna; harmonic suppression; circular polarization

New parameter tuning method for LCC/LCC compensated IPT system with constant voltage output based on LC resonance principles

Compensation topologies with constant current (CC) or constant voltage (CV) play essential roles in inductive power transfer (IPT) systems. This article describes basic LC resonance principles, which can analyse the output characteristics of all the compensation topologies with CC or CV outputs. By combining LC principles, a new parameter tuning method for LCC/LCC topology with CV output is proposed, followed by efficiency analysis and sensitivity analysis as per various configurations. Moreover, comparing with conventional topologies, it indicates that the LCC/LCC topology has three advantages: (i) The output voltage is load-independent, and it can easily achieve zero phase angle (ZPA) or zero voltage switching (ZVS); (ii) This topology can free the design from the restrictions enforced by the loosely coupled transformer parameters; (iii) The topology is equipped with high-order harmonic suppression capability. Finally, a 1300-W laboratory-scale prototype with a 15 cm air gap was built to verify the theoretical analysis. The experimental results demonstrate the feasibility and superiority of the proposed LCC/LCC IPT system with new parameter tuning method.

Dual-band aperture coupled antenna with harmonic suppression capability

The paper presents an aperture-coupled dual-band linearly-polarized antenna with harmonic suppression capability, operating at frequency 2.45 GHz and 5.00 GHz. In purpose of improving the directivity of antenna at the operating frequency of 2.45 GHz and 5.00 GHz, a modified inverted π-shaped slot-etched patch on the lower layer of the stacked antenna is introduced alongside the 50 Ω feed line. The harmonic suppression capability is achieved by the introduction of U-slot and asymmetrical left-right-handed stub at the transmission feed line, suppressing unwanted harmonic signals from 6.00 GHz up to 10.00 GHz. The final design of the antenna has produced very good reflection coefficient of -18.87 dB at 2.45 GHz and -19.57 dB at 5.00 GHz with third and higher order harmonic suppression up to -4 dB.

Low-Profile Independently- and Concurrently-Tunable Quad-Band Antenna for Single Chain Sub-6GHz 5G New Radio Applications

This paper presents a quad-band frequency agile antenna, with independent and concurrent frequency tunability in each band, for a tunable, concurrent, quad-band single chain radio receiver for 5G New Radio (NR). More specifically, the antenna comprises of four planar slots etched in a ground plane and fed through a single microstrip feedline, without any impedance matching network. The structure is optimized to maximize isolation between the individual slots and their respective resonant frequencies. Furthermore, a novel high order harmonic suppression method is demonstrated, which controls the current distribution via creating a fictitious short circuit in the slot antenna–enabling the antenna to achieve a much wider tuning range. Numerical simulations are verified using experimental implementation and measurements, with good agreement observed. The four slots resonate around the 830 MHz, 1.8 GHz, 2.4 GHz and 3.4 GHz frequency bands, which are independently tuned (using a varactor diode in each slot) to achieve tuning ranges of approximately 64%, 66%, 27% and 33%, respectively. More importantly, the contiguous four bands covers a total frequency tuning from 0.6 to 3.6 GHz i.e. a tuning range of approximately 143%. Finally, far-field measurements are performed and the antenna is evaluated in over-the-air testbed (quad-band radio receiver), which measures the Error Vector Magnitude performance for the individual channels. Good performance is observed, confirming acceptable isolation performance between the four bands. The data reported in this paper is available, from ORDA-The University of Sheffield Research Data Catalogue and Repository, at https://doi.org/10.15131/shef.data.11219000.v1 .

Online Prediction of Milling Inner Hole Roundness Error Based on Accurate SSEM Value Extraction

To improve the machining accuracy and production efficiency of precision components with deep hole structures, an online prediction method of the inner hole roundness error, which cannot be directly measured in real time during the machining process, is proposed in this paper. For online prediction of the workpiece roundness error (WRE) during machining, a predictive model based on correlation analysis and a proportional method is proposed according to the spindle synchronous error motion (SSEM) by three‐probe method testing. To improve the prediction accuracy of the WRE, a particle swarm optimization (PSO) algorithm is introduced for optimizing a probe mounting angle of a three‐probe method, and a harmonic wavelet method for SSEM feature extraction is proposed. Using the PSO algorithm, the optimal probe mounting angle of the three‐probe method is obtained, the influence of spindle surface roundness on SSEM is eliminated, and the higher‐order harmonic suppression of the three‐probe method is avoided effectively. By the harmonic wavelet method, the accurate SSEM extraction is enhanced and the WRE prediction accuracy is promoted. The experiments show that the inner hole roundness error online prediction method proposed in this paper has high prediction accuracy.

A Novel Parameter Tuning Method for a Double-Sided LCL Compensated WPT System With Better Comprehensive Performance

Wireless power transfer (WPT) has attracted a large amount of attention owing to its inherent advantages such as convenience, safety, low maintenance, being weather proof, etc. A parameter tuning method is crucial for a WPT system due to its function of reducing reactive power and improving system efficiency. Three deficiencies of the conventional double-sided inductor–capacitor–inductor (DS- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> ) compensated system, i.e., low design freedom, weak high-order harmonic suppression capability, and discontinuous input current of a full-wave diode rectifier (FDR), are first analyzed by means of theoretical derivation, numerical calculation, and Pspice simulation. In order to overcome these disadvantages, a novel parameter tuning method is proposed. The characteristic of constant current output of the proposed DS- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> system is analyzed, followed by a detailed derivation about secondary compensation inductance. Theoretical analysis indicates that the proposed system has four attractive characteristics: higher design freedom, reduced coil current, enhanced high-order harmonic suppression capability, and continuous input current of the FDR. The overall efficiencies of two comparative WPT prototypes, tuned by conventional and proposed methods, are 87.3% and 90.2%, respectively. Experimental results show great coincidence with theoretical analysis, demonstrating the superiority of the newly proposed parameter tuning method.

A dual band rectifying antenna for RF energy harvesting

This paper presents a compact dual band rectenna consisting of an open ended microstrip line antenna useful for sensing UMTS and RFID microwave signals. The designed antenna has a Sierpinski fractal geometry loaded on the ground surface and resonates at 2.1 GHz and 5.8 GHz. In the proposed structure, suppression of higher order harmonics is realized with improved RF to DC conversion efficiency in both the resonating bands. A voltage doubler rectifier configuration is used for rectifying the RF signal sensed by means of a receiving antenna and the output is passed through a DC block capacitor. An RF 7 to DC conversion efficiency of 79% and 86% is achieved for a 1 KΩ load at 2.1 GHz and 5.8 GHz, respectively. The overall size of the designed antenna is 40 × 40 × 1.6 mm3 and the rectifier is 40 × 48.6 × 0.762 mm3.

Control of Higher Order Harmonics and Spurious Modes for Microstrip Patch Antennas

In rectifying or active antenna systems, the higher order modes can hamper the system efficiency, and thus, the filter antennas are used to eliminate the harmonic radiation. In this paper, the distribution of standing wave fields in patch antenna having been presented and then the characteristic mode theory having been employed, the influences of feeding location and the indentation of patch edges on the suppression of higher order harmonics and their spurious modes are investigated. It is indicated that indenting the radiating edges of the patch element works more effectively on the control of spurious modes while indenting the non-radiating edges can eliminate the harmonics by shifting down the fundamental mode. By selecting feed position and indenting the patch edges, a microstrip patch antenna with both harmonic and spurious mode controls is proposed.

A Transplantable Frequency Selective Metasurface for High-Order Harmonic Suppression

A transplantable frequency selective metasurface element (FSMSE) for high-order harmonic suppression (HS) is presented in this paper. The proposed harmonic free FSMSE can be integrated with arbitrary frequency selective surfaces (FSSs) operating at the same frequency band. The designed HS-FSMSE is applied to two different types of FSSs for verification of harmonic suppression, respectively. One is a multilayer sub-wavelength patch-grid FSS that has weak resonant behavior, and the other is a complementary resonant loop FSS which has strong resonant behavior, especially for high-order harmonic waves. By integrating with HS-FSMSE, the two kinds of FSSs operating at 10 GHz are free of harmonic transmission bands up to 30 GHz. The simulation and measurement results show feasibility of the harmonic suppression FSMSW and good polarization and angle stabilities.

Theoretical and experimental study of arbitrary microwave signal generation through LiNbO3 MZI

Microwave photonics system provides high bandwidth capabilities of fiber optic systems and also contains the ability to provide interconnect transmission properties, which are virtually independent of length. In this paper, we have studied the effect of higher order dispersion, harmonic suppression of forth order with different modulation values. We found that, higher order harmonic suppression and frequencies are varying with the electrical drive signal for different modulation depths. It is apparent from the calculated result that the harmonic suppression increases as the modulation depth increases. In all the case, it is observed that the harmonic suppression is varying, but the frequencies are same for different values of depth of modulation. The analysis performed by the other researchers describes that, harmonic suppression varies with frequency. But in our analysis, we found that harmonic suppression is independent of frequency. Thus, it can be beneficial; as electric signal is stable over the tuning band. In this paper, we derived the step by step expression for harmonic suppression for better understanding.

Selective suppression of high-order harmonics within phase-matched spectral regions.

Phase matching in high-harmonic generation leads to enhancement of multiple harmonics. It is sometimes desired to control the spectral structure within the phase-matched spectral region. We propose a scheme for selective suppression of high-order harmonics within the phase-matched spectral region while weakly influencing the other harmonics. The method is based on addition of phase-mismatched segments within a phase-matched medium. We demonstrate the method numerically in two examples. First, we show that one phase-mismatched segment can significantly suppress harmonic orders 9, 15, and 21. Second, we show that two phase-mismatched segments can efficiently suppress circularly polarized harmonics with one helicity over the other when driven by a bi-circular field. The new method may be useful for various applications, including the generation of highly helical bright attosecond pulses.

Compact single/dual band BPF with harmonic suppression using open‐loop resonator and L‐shaped coupling arm

A new approach is presented to design a widestopband single and dual-band bandpass filter (BPF) using L-shaped coupling-arm and open-loop resonators (OLRs). Non-uniform gap between the L-shaped coupling-arm and OLR and the length of the coupling-arm lead to the selective and collective suppression of higher order harmonics. Using voltage wave analysis, it is shown that the coupling-coefficient reduces to zero for certain harmonics. To demonstrate the application of the proposed technique single and dual-band BPFs is designed and fabricated. Second- and fourth-order single-band BPFs are fabricated for the centre frequency of 2.24 GHz. Harmonic suppression up to 5.8 fo with the suppression level >30 dB is achieved in second-order BPF. One more second-order BPF is designed and fabricated using stub-loaded stepped impedance OLR. This BPF displays widestopband up to 8.4 fo with the suppression level of 30 dB. Further a compact dual-band BPF is also designed and fabricated. The response shows the harmonic suppression up to 5.3 fo. The measured results are in good agreement with the full-wave simulation performed by high-frequency structure simulator.

Refraction effects in soft x-ray multilayer blazed gratings.

A 2500 lines/mm Multilayer Blazed Grating (MBG) optimized for the soft x-ray wavelength range was fabricated and tested. The grating coated with a W/B4C multilayer demonstrated a record diffraction efficiency in the 2nd blazed diffraction order in the energy range from 500 to 1200 eV. Detailed investigation of the diffraction properties of the grating demonstrated that the diffraction efficiency of high groove density MBGs is not limited by the normal shadowing effects that limits grazing incidence x-ray grating performance. Refraction effects inherent in asymmetrical Bragg diffraction were experimentally confirmed for MBGs. The refraction affects the blazing properties of the MBGs and results in a shift of the resonance wavelength of the gratings and broadening or narrowing of the grating bandwidth depending on diffraction geometry. The true blaze angle of the MBGs is defined by both the real structure of the multilayer stack and by asymmetrical refraction effects. Refraction effects can be used as a powerful tool in providing highly efficient suppression of high order harmonics.

Design of broadband class-F power amplifier with high-order harmonic suppression for S-band application

A broadband class-F power amplifier for an S-band handset device is integrated on a 3 × 3 × 0.82 mm3 die using an InGaP/GaAs HBT process. With LC serial harmonic traps immersed into the broadband output matching circuit, good harmonic suppression performance can be achieved. A pure resistive impedance of the matching circuit, but near zero at second and infinite at third harmonic frequency, which enhances the efficiency, is obtained across 1.8–2.5 GHz. Tested with a continuous wave (CW) signal, the PA delivers an output power of 34 dBm and achieves a PAE of 57% at 2 GHz. In addition, excellent harmonic suppression levels of less than −53 dBc across the second to fifth harmonic are obtained.

Impedance-Varying Broadband 90° Branch-Line Coupler With Arbitrary Coupling Levels and Higher Order Harmonic Suppression

We propose a new design methodology to broaden the bandwidth of a single-section 90° branch-line coupler (BLC) with arbitrary coupling level. The method used here to broaden the BLC bandwidth is to replace conventional uniform transmission lines that would never be feasible in many implementations with nonuniform lines governed by a truncated Fourier series. Based on how impedances are profiled, the fractional bandwidth of a single-section 90° 3-dB BLC is extended to 57%, and the realization of broadband BLCs with predefined coupling levels is also possible. Furthermore, higher order harmonics are suppressed by enforcing BLC $S$ -parameters to match the design requirements only at a given frequency range. A systematic design approach based on the even-odd mode analysis is first presented. Then, three examples of 3-, 6-, and 9-dB BLCs are demonstrated at a 3-GHz center frequency. The obtained theoretical response, supported by full-wave electromagnetic simulations and measurements, justifies the design concept.

Using Microstrip LPF in Gysel Power Divider for Extreme Size Reduction and Higher Order Harmonic Suppression

AbstractThis paper presents a new design of a compact Gysel power divider with harmonic suppression. It comprises six similar low-pass filters in lieu of six conventional transmission lines in the Gysel power divider. Not only does the proposed power divider extremely reduce the occupied area to 22.7% of the conventional Gysel power divider at 900 MHz, but also it features the higher order harmonic rejection. Simulation and measurement results show good insertion loss, return loss, isolation, and wide stopband bandwidth, while maintaining high-power handling capability over the Wilkinson power divider.

Optimised high‐efficiency Class E radio frequency power amplifier for wide bandwidth and high harmonics suppression

A Class E power amplifier offers high efficiency approaching 100% for an ideal case. A new wide bandwidth Class E power amplifier design has been introduced combining a parallel-circuit load network with reactance compensation technique and high-order harmonic suppression circuit. The proposed topology has been discussed based on theory and its experimental verification. A hardware prototype was designed and built, and measurement results showed drain efficiency of 70% and second harmonic rejection of more than 84 dBc (as well as higher harmonics), and output power level more than 6.5 W with ±0.5 dB power flatness, across very high frequency (VHF) band (136-174 MHz). The performance achieved demonstrated highest harmonic suppression across wide bandwidth for VHF range according to authors' knowledge. Simulations of power performance (i.e. efficiency and output power) were verified by measurements, and good agreements were obtained.