Insertion Loss Characteristics Research Articles

Single- and dual-band high-order polarization rotating frequency selective surface

Abstract This work presents the design and development of dual- and single-band polarization rotating frequency selective surfaces (PR-FSSs) based on aperture-coupled patch multimode resonators. Initially, an open-loop slot is incorporated into the patch of a second-order resonator to design a dual-band second-order PR-FSS (DPR-FSS), which enables effective polarization rotation and frequency selection across two distinct passbands. Then, to develop a single-band fourth-order PR-FSS (SPR-FSS), we introduce a metallic via into the DPR-FSS. This modification results in a single-band fourth-order response. The SPR-FSS offers a bandwidth of 41% with minimal insertion loss and high roll-off characteristics. Finally, experiments are conducted to verify the performance of the proposed structures. Good agreement can be observed between simulation and measurement.

Asymmetric CMOS switch for Dicke radiometer in millimeter-wave imaging system

An asymmetric Dicke switch implemented in bulk complementary metal-oxide-semiconductor (CMOS) technology is proposed to achieve high isolation and low insertion loss in the D-band. A Dicke switch eliminates the noise in the signal transmitted from the antenna, providing a high signal-to-noise ratio at the receiver front end. The proposed Dicke switch employs an asymmetric configuration for the signal transmission path and the reference noise incidence path, which overcomes the trade-off relationship between the insertion loss and isolation characteristics. The proposed asymmetric structure presents an optimum impedance in the reference component to achieve the same characteristics as those of the noise incident from the antenna port. The Dicke switch is fabricated using the 65-nm RFCMOS process with a chip size of 350 × 490 μm2, including all the pads. The measurement results in the D-band present an insertion loss below 2.8 dB in the on-state and isolation above 22 dB in the off-state. The minimum insertion loss and maximum isolation were measured to be 1.7 dB at 155 GHz and 29 dB at 122 GHz, respectively.

Frequency Characteristics of Insertion Loss and Loop Gain of VSCC Feedback Active EMI Filters

Frequency Characteristics of Insertion Loss and Loop Gain of VSCC Feedback Active EMI Filters

Realization of an optical nanostructure 4×1 multiplexer based on metal-insulator-metal plasmonic waveguides.

The optical multiplexer was created at a nanoscale plasmonic structure utilizing the finite element method (FEM) with COMSOL version 5.5 software to enable maximum light confinement, high-speed optical systems, and a tiny structure. The metal-insulator-metal technology at a nanoscale dimension is used for creating the 4×1 multiplexer. In this design, the transmission threshold (T t h r e s h o l d ) is selected to be 100% for separating between logic "1" and logic "0" at a 1310nm operating wavelength. The modulation depth (MD), contrast ratio (CR), and insertion loss (IL) characteristics were explained to evaluate the performance of the multiplexer. The CR has 3.48dB, the MD offers an ideal performance with 95.28 %, and the IL has 3.31dB.

Numerical Insight Into the Origin of Nonreciprocity and Performance Enhancement in Nonreciprocal Bandpass Filters Using Evolutionary Algorithm

In this paper, a non-reciprocal filter with enhanced directivity is analyzed methodically, and the filter parameters are optimized using an evolutionary algorithm. The non-uniform spectral dispersion of power among the harmonics in opposite directions is substantiated with the aid of filtering polynomials. These polynomials indicate the origin of at least one transmission zero within the passband in the reverse direction, thereby promoting the non-reciprocal filter response. The filter’s return loss, insertion loss, and isolation characteristics exhibit a trade-off that demands an optimization algorithm to effectuate the judicious choice of circuit parameters. This problem is addressed by designing a 150 MHz lumped element non-reciprocal bandpass filter based on the parameters extracted using an evolutionary algorithm based particle swarm optimization (PSO). The simulated and measured results comply well with the modeling, and the results exhibit maximum directivity of 28.2 dB without degradation in insertion loss (1.1 dB) and return loss (16.2 dB) within the passband. The algorithm can be utilized in designing non-reciprocal filters having different center frequencies and bandwidths.

W-Band GaN HEMT Switch Using the State-Dependent Concurrent Matching Method

In this study, a W-band GaN single-pole single-throw (SPST) switch was designed. To realize the pass and isolation modes of the SPST switch, we proposed the design technique of a unit branch consisting of one transistor and one transmission. The characteristic impedance and length of the transmission line were determined by the impedance and the angle at which the straight line connecting the impedances of the on and off states of the transistor meets the real axis of the Smith chart. Using the design technique, the matching networks for the pass and isolation modes of the switch are concurrently completed. In order to improve the insertion loss and isolation characteristics of the switch, the size of the transistor and the number of unit branches were investigated. To verify the feasibility of the proposed design technique, we designed the W-band SPST switch using a 100 nm GaN HEMT process. The measured insertion loss and isolation were below 2.9 dB and above 23.5 dB, respectively, in the frequency range from 91 GHz to 101 GHz.

Novel Nth/2Nth Order Two-Band Bandpass Filters for Sub-6 GHz 5G Applications

In this paper, a new design method is proposed for multi-mode two-band bandpass filters based on combining a square loop resonator that has a capacitive perturbation element and short-circuited stubs. This concept is a new multi-mode two-band filter design having Nth and 2Nth order for the first and second passbands that appear in f0 and 3f0 center frequencies, respectively. It has been shown that the number of transmission modes in each passband can easily be increased by periodically cascading one unit filter cell including one square loop resonator and two short-circuited stubs. This also provides a reconfigurable filter property, namely the obtaining of two different filtering characteristics in the second passband by means of the reverse and straight placing of the cascaded unit filter cells in the horizontal axis. Two 2nd/4th order two-band bandpass filter prototypes are fabricated and tested to validate the proposed design method. The total surface areas of these fabricated prototypes are 26.0 mm × 9.0 mm and 24.4 mm × 16.8 mm, and the measured insertion losses in the first/second passband are about 0.63 dB/0.96 dB and 0.59 dB/0.83 dB. It is observed that the filter prototypes have the advantages of low insertion loss, compact size, and flexible filtering characteristics. The designed filters are suitable for operation in the 5G spectrum, which includes a range of radio frequencies sub-6 GHz.

Determination of Insertion Loss of noise barriers in Spanish roads

The evaluation of the effectiveness of noise barriers have addressed, in some research studies, the intrinsic characteristics of barriers, such as noise absorption or transmission; in other studies, it has been based on the global characteristics of Insertion Loss (IL), which is defined as the difference in the noise level before and after the installation of the barrier. IL is an extrinsic characteristic of noise barriers, depending largely on the site in which the barrier is placed. This research investigated the in situ effectiveness of existing noise barriers by using the indirect IL method established in the international standard ISO 10847:1997. Measurements were performed at thirty sample sites, distributed among the three most frequent types of material found on Spanish roads (earth berms and concrete and metal walls).The results revealed moderate IL values. Results at a distance of 25 m were clearly below the expected effectiveness of a noise barrier. The IL values for the three types of barriers were similar. The best noise reduction effect was in the frequency range of 125–8000 Hz, at which the traffic noise is dominant. In most cases, the dimensions of the barriers did not seem to have been determined taking into account diffraction requirements.

A microstrip folded compact wideband band‐pass filter with wide upper stopband

A miniaturized wideband band-pass filter with a 3-dB fractional bandwidth of 109.3% (1.53 GHz to 5.22 GHz), high out-of-band attenuation greater than 25 dB, and wide upper stopband up to 14 GHz is proposed. The design consists of a dual-composite right/left handed resonator, embedded open-circuited stub, and a pair of quarter-wavelength short-circuited stubs. These elements are coupled in the near distance to form a miniature filter with a compact occupied area of 0.21 λg× 0.19 λg (≈ 0.013 cm2). The optimized filter has multi-transmission poles in the passband, substantially improving the return loss and insertion loss characteristics. The behavior of the passband and stopband is verified against the results of a lumped element model and matrix analysis with a full-wave moment-based analysis and actual measurements. The results of this verification and a comparison with the performance of filters in other references indicate that the proposed filter is very efficient and applicable to compact microwave systems.

Complex Permittivity and Permeability Extraction of Ferromagnetic Materials For Magnetically Tuned Microwave Circuits

Ferromagnetic materials, such as ferrites, are employed for magnetically tuned radio frequency (RF) circuits. Ferrites exhibit both electric permittivity and magnetic permeability and independent RF characterization of these two properties is crucial for accurate design and modeling of RF circuits. A method that independently extracts each property over Wi-Fi frequencies is presented here, where complex permittivity and permeability of ferrite nano-particles are extracted using resonance frequency sensitivity of a 3D printed metallic cavity to various samples under test and their placement in the cavity. Air-filled 3D printed rectangular cavity using acrylonitrile butadiene styrene (ABS) are shielded using copper sheets; the structure of air-filled cavity is designed to excite TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">101z</sub> as the dominant resonance mode that resonates at 2.4 GHz. A cylindrical shape material under test (MUT) was added to the cavity at different positions for high electric and magnetic fields, while the resonant frequency change and degradation in quality factor of the resonant cavity are employed for accurate independent extraction of electric permittivity and magnetic permeability of MUT. The sample was prepared with volumetric distribution of 60:40 nanoparticles to glue ratio. In particular, a 3D printed composite sample of ABS with NiFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> magnetic nanoparticles is placed in positions of high electric or high magnetic energy densities of the metallic cavity, while any changes in resonant frequency and its frequency selectivity are observed from the cavity insertion loss characteristics. Both perturbation theory (as analytical) and finite element method (as numerical) techniques are employed for extraction of complex permittivity and permeability of NiFe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> . The perturbation theory provides accurate extraction, which is also numerically confirmed using curve fitting of the full wave simulated scattering parameters to the measured results.

240 GHz meta‐surface band pass filter and lens integration in 6G telecommunication systems

Abstract240 GHz operated meta‐surface band pass filter consisting of split‐ring resonator (SRR) matrix was simulated and measured as single and second order modes. The filter was integrated with hemispherical and Luneburg type of antenna lenses. The SRR meta‐material filter was recommended component for 6G telecommunication applications characterizing measured values of 80 GHz bandwidth, low insertion loss (−0.75 dB) and good attenuation (−8 dB) characteristics close to the band pass region, and the filters can be cascaded to enhance its filtering characteristics.

Evaluation of a cross-grid microring resonator electro-optic switching array

Herein, a cross-grid microring resonator electro-optic switching array model is proposed on the basis of the coupled mode theory, electro-optic modulation theory, and microring resonance theory. The proposed device has N+1 horizontal channels, N vertical channels, and 2N microrings with equal radii. By applying an operating voltage to the microrings in the array unit in various ways, the switching function of the N+1 horizontal channel can be realized. Taking the structure of 9 × 8 channels as an example, the output spectrum, insertion loss, crosstalk, extinction ratio, and other characteristics of this switching array device under a resonant wavelength of 1550 nm are simulated and analyzed.

Research on acousto-optic switch based on optical tamm state

An acousto-optic switch scheme based on optical tamm state (OTS) is proposed. The acousto-optic switch’s structure is one-dimensional photonic crystal heterostructure, which is composed of three materials: silicon dioxide, gallium arsenide and tellurium dioxide. All three materials are acousto-optic materials, which can ensure the acousto-optic effect when the ultrasonic wave and the light wave are incident at the same time. Due to the acousto-optic effect, the refractive index and thickness of one-dimensional photonic crystal heterostructures are changed by ultrasonic. The acousto-optic switch changes the ultrasonic amplitude to shift the intrinsic wavelength of OTS to the shorter wave direction. With the increase of ultrasonic amplitude, the intrinsic wavelength of OTS hardly changes after the amplitude exceeds 0.4 nm. This means that the ultrasonic wave with an amplitude of 0.4 nm can shift the intrinsic wavelength to 1538 nm. The acousto-optic switch realizes the on-off function within the permitted range. In this paper, the theoretical model of the acousto-optic switch is established. The propagation of ultrasonic wave in one-dimensional photonic crystal heterostructure is analyzed by theoretical model. The propagation of light in the medium after acousto-optic effect is analyzed by transmission matrix method. The simulation is carried out through COMSOL Multiphysics software. The results show OTS exists and localization can be seen in the electric field diagram. The acousto-optic switch of 1548.8–1551.7 nm can be realized by applying certain amplitude of ultrasonic or not. In this wavelength range, the extinction ratio is not lower than 12 dB and the insertion loss is not higher than 0.97 dB. The maximum extinction ratio is 13.17 dB, and the minimum insertion loss is only 0.65 dB. The acousto-optic switch of 1536.6–1543.3 nm can be realized by applying ultrasonic wave with amplitude corresponding to the length of incident light. In this wavelength range, the extinction ratio is not lower than 12 dB, and the insertion loss is not higher than 0.99 dB. The maximum extinction ratio is 13.15 dB, and the minimum insertion loss is only 0.65 dB. The response time of the acousto-optic switch is less than 13 ns. The acousto-optic switch has the characteristics of high extinction ratio and low insertion loss. It has a good application prospect and can be effectively applied in future optical communication.

Fluid Acoustic Properties of Improved Hydraulic Mufflers with Extended Necks

The acoustic properties of three improved hydraulic mufflers with extended necks are investigated theoretically and experimentally. The effect of length and slope of the conical tube, and the perforations on the extended tube is studied on the resonance frequency and the insertion loss. The plane wave approach is used for the constant and the variable area tubes, while Sullivan and Peat's method is applied for the perforation tube unit. Theoretical predictions are compared with experiments for these three different hydraulic noise suppressors, which are fabricated. It is shown that the resonance frequency and the insertion loss characteristics may be controlled by the length and the slope of the conical tube and perforation porosity of the extended tube without changing the expansion chamber volume. Finally, the effect of the cross-sectional shape of the expansion chamber is investigated.

A quintuple mode resonator based bandpass filter for ultra-wideband applications

This paper presents a new configuration of quintuple mode resonator for designing a bandpass filter for ultra-wideband applications. The multiple-mode resonator is constituted by two capacitive ended rectangular stubs and connected with a high impedance microstrip line. Inter-digital coupled feed lines are designed to excite the resonator. Standard analytical approach based on odd-/even-mode analysis is applied to examine the resonant characteristics of the multi-mode resonator. The proposed filter has the characteristics of low insertion loss, wide stopband along with compact size. The bandwidth (|S11| ≤ − 10 dB) of the proposed filter has been observed to vary from 3.11 to 10.63 GHz with low insertion loss value uniform around − 0.8 dB. A wide stopband with attenuation of more than 15 dB (11.27–20 GHz) is observed for the proposed design. The filter occupies a compact area equal to 23.4 mm × 10 mm (about 0.43λg × 0.09λg, where λg is the guided wavelength at 6.85 GHz). The simulated results agree well with the measured results validating the effectiveness of the work.

40 dB-Isolation, 1.85 dB-Insertion Loss Full CMOS SPDT Switch with Body-Floating Technique and Ultra-Small Active Matching Network Using On-Chip Solenoid Inductor for BLE Applications

In the IoT/wearable devices, the antenna is shared with the receiver and transmitter of the transceiver. This requires the control of the switch between the antenna and the control circuitry to achieve both low insertion loss and high isolation. This paper presents a low insertion loss and high isolation switch based on Single Pole Double Throw (SPDT) switch for 2.4 GHz Bluetooth low power (BLE) transceiver. The body-floating technique is used to improve the insertion loss’s performance. An ultra-small on-chip matching network with high Q-factor is proposed. The shunt transistors are used as active shunt capacitors that create the active matching network to improve isolation characteristics. The proposed SDPT switch was designed using 55 nm CMOS process with the total area of 110 μm × 210 μm. The insertion loss and isolation characteristics of the proposed SPDT switch observed at 2.4 GHz are 1.85 dB and 40 dB, respectively.

Low windage resistance frequency‐selective rasorber based on windmill‐shape coupling line arrays

In this Letter, the authors report on the analysis, design, fabrication and measurement of a low windage resistance frequency selective rasorber (FSR) based on windmill-shape coupling slot line arrays. A lossy structure is added to the traditional frequency selective surface structure to make up a FSR with the characteristics of small insertion loss within the passband and weak reflection at frequencies below and above the passband meanwhile. In addition, the hollow structure can reduce windage resistance effectively. The measurements show that an insertion loss of 1.01 dB can be obtained at 7.71 GHz, while both lower and upper passband edges have at least 10 dB reflection reduction under the normal incidence. Both simulation and experiment results exhibit that the proposed FSR is insensitive to both transverse-electric (TE) and transverse-magnetic (TM) polarisation. The proposed FSR can be applied in the field of radome, cloaking and other microwave applications.

Acoustic radiation and cold point defect in boiler tube arrays based on phononic crystals theory

The structure of heat exchangers is similar to two-dimensional phononic crystals in boilers. In this study, with the given tube array parameters of the heat exchanger, we investigate the effects of sound source location and different frequencies on acoustic radiation. Based on phononic crystals theory, the Plane Wave Expansion method is used to calculate the band gap structure, and the Finite Element method is used to study the acoustic insertion loss and radiation characteristics. In the simulations, constant boundary conditions are imposed on the boundary between the air and steel boards, the radiation boundary conditions are applied to all boundaries of the air domain cell, and the free triangular is used in the simulated domain. When there is tube leakage, a cold point defect exists in the tube arrays. We also study the sound transmission characteristics of the cold point defect at a different location. This study can provide an innovative concept and method for leakage location and sonic soot cleaning in boiler tube arrays.

Investigation of AWG demultiplexer based SOI for CWDM application

9-channel Arrayed Waveguide Grating (AWG) demultiplexer for conventional and tapered structure were simulated using beam propagation method (BPM) with channel spacing of 20 nm. The AWG demultiplexer was design using high refractive index (n~3.47) material namely silicon-on-insulator (SOI) with rib waveguide structure. The characteristics of insertion loss, adjacent crosstalk and output spectrum response at central wavelength of 1.55 μm for both designs were compared and analyzed. The conventional AWG produced a minimum insertion loss of 6.64 dB whereas the tapered AWG design reduced the insertion loss by 2.66 dB. The lowest adjacent crosstalk value of -16.96 dB was obtained in the conventional AWG design and this was much smaller compared to the tapered AWG design where the lowest crosstalk value is -17.23 dB. Hence, a tapered AWG design significantly reduces the insertion loss but has a slightly higher adjacent crosstalk compared to the conventional AWG design. On the other hand, the output spectrum responses that are obtained from both designs were close to the Coarse Wavelength Division Multiplexing (CWDM) wavelength grid.

光锁相环路中声光移频器插入损耗特性研究及优化

光锁相环路中声光移频器插入损耗特性研究及优化