Search

A single-feed, circularly polarized, log periodic dipole array (CPLPDA) with size-reduced, cross-dipole elements is proposed. Size reduction in elements is achieved with curved T-shaped, top loading. Compared to the full-sized CPLPDA elements, the achieved element-length reduction is 50%. With six elements, the antenna shows a -10-dB impedance bandwidth (IBW) of 87.0%, and a 3-dB axial ratio bandwidth (ARBW) of 50.0% in measurement. The common bandwidth (CBW) between the -10-dB IBW and 3-dB ARBW of the CPLPDA is 50.0%. The peak realized gain in the direction of the shortest element is 6.60 dBi over the CBW.

Straw is a substantial agricultural by-product for biogas production. Hydrolysis of straw is found to be a rate-limiting step during its anaerobic digestion and could be enhanced by pretreatment. In this paper, the effect of various combinations of particle size reduction, autoclaving, and low-level Fenton reaction was studied on straw for biogas production. Grinding of straw contributed to the maximum increase in the biomethane potential. Only Fenton or only the autoclave process improves the kinetics slightly but does not considerably improve the biomethane potential. Combining autoclaving and low-concentration Fenton pretreatment considerably improves the BMP values. Lignin content, CHNSO elemental analysis, Scanning Electronic Microscopy (SEM), Simon’s staining, infrared spectroscopy (DRIFT and ATR), Nuclear magnetic resonance spectroscopy, and wide-angle X-ray diffraction analysis (WAXD) were used to characterize the physical and chemical changes of straw due to pretreatment. Results show a poor correlation between biogas production and the different physical and chemical biomass characteristics. It makes it difficult to explain the outcome of various pretreatment methods applied to biomass. Without further improvement and development of analytical techniques, the prediction of the biomethane potential of a feedstock with the aid of pretreatment can only be considered in case-by-case studies.

Dried sphagnum moss was ground using a pin mill and a hammer mill under various operating conditions, i.e., changes in the rotor frequency and feed rate. The specific energy consumption of the size reduction was recorded. The ground powder was characterized by median particle size, width of size distribution (span), loose and tapped bulk densities, and the Hausner ratio. Pin milling used less energy for size reduction than hammer milling, especially when the target size was below 100 μm. In both milling methods, the specific energy consumption was mainly caused by the rotor frequency used. However, in pin milling, the specific energy consumption was also dependent on the production rate: the higher the rate, the higher the energy consumption. No such dependence was observed with the hammer mill. The span was wider in pin milling than hammer milling in the intermediate product size range although the difference decreased at the fine and coarse ends. A similar pattern was found for bulk densities. However, the flowability of powder, as characterized by the Hausner ratio, was comparable between the grinding methods.

This paper describes the results of studies on higher torque density of automotive auxiliary motors based on electromagnetic field analysis. Dual stator axial-gap PM motors achieve higher torque density than radial-gap motors in a flat motor shape. Therefore, an axial-gap motor was designed based on a design policy different from that in the past to reduce its volume by half of the radial-gap motors for automotive applications and was experimentally evaluated using a prototype motor. In order to improve the torque density, a double axial-gap motor structure was adopted to achieve wide torque generation areas and was optimally designed, reducing the volume by 44% compared with the existing model. It was experimentally evaluated using a prototype motor.

This article analyses the effect of the size reduced Silver (Ag) loaded hydrogel by (a) lyophilisation (S1) (b) ball milling (S2) techniques and its effect on anti‐bacterial activity. The g loaded hydrogel, S1 and S2 shows an increase in swelling with an increase in pH. The swelling is more for Ag loaded hydrogel in low pH. For pH above 7, the swelling ratio of Ag loaded hydrogel and S1 are almost the same while S2 shows very less swelling. The anti‐bacterial studies reveal that S1 and Ag loaded hydrogel reacted well in S. aureus (Staphylococcus aureus) but no zone formation was seen in S2 .whereas no zone was formed in S1 and S2 for E‐coli (Escherichia coli). As the next step, the anti‐bacterial activity of Ag loaded hydrogel with the addition of curcumin (CS1―size reduced by lyophilisation, CS2―size reduced by ball milling) and turmeric (TS1―size reduced by lyophilisation, TS2―size reduced by ball milling) were investigated. In case of E.coli, a zonal formation of 1.2 cm for TS1 and 1.1 cm for TS2 and 1 cm for CS1 and 0.2 cm for CS2 was observed. For S.aureus, 1.1 and 1 cm were seen for TS1 and CS1. TS2 and CS2 did not show any zone formation. These studies clearly show that size reduction by lyophilisation (S1, TS1 and CS1) is more efficient in all the cases when compared to the ball milling technique (S2, TS2 and CS2). Comparing TS1 with S1 and CS1, TS1 has highly efficient/effective anti‐bacterial properties than S1 and CS1. Therefore, lyophilised hydrogel incorporating turmeric and silver (TS1) is an excellent choice compared to using curcumin for wound dressing applications.

This paper presents the design, analysis, and fabrication of a new miniaturized microstrip branch line coupler (BLC) with high harmonics suppression. The T-shaped resonators, open stubs cross-shaped resonators and radial stubs are used in the proposed coupler design. The designed BLC operates at 1 GHz frequency, which can suppress up to 5th spurious harmonics with a 20 dB level of attenuation. High miniaturization of about 86% is obtained for the proposed BLC, which is corresponding to the normalized size of 0.009 λg2. The measured values of isolation and return loss are obtained 28 dB and 29 dB, respectively, while the measured insertion loss of better than 0.2 dB is achieved at the operating frequency. Additionally, the operating bandwidth of the designed coupler ranges from 0.905 GHz up to 1.105 GHz, which shows a 200 MHz operating bandwidth or a fractional bandwidth (FBW) of 20%. The presented BLC is fabricated and measured, where the measurements confirm the simulated results. The designed coupler shows desirable performance compared to the recent designed couplers.

A Ground-Based Augmentation System (GBAS) monitors the signals of Global Navigation Satellite Systems and broadcasts differential correction signals. It relies on Multipath Limiting Antennas (MLAs) that can receive signals over almost the entire upper hemisphere while greatly attenuating signals reflected from the ground. The current Federal Aviation Administration (FAA)-approved system utilizes an MLA that is approximately 182.9 cm tall. In this paper, a substitute MLA is designed that is only 97.05 cm tall (approximately 44% reduction). The size reduction is accomplished by reducing the number of array elements from 19 to 11. We developed a novel self-cardioid antenna element that allows for this reduction.

This paper presents a review of the current applications of Micro-Electro-Mechanical Systems (MEMS) in the robotics and industrial applications. MEMS are widely used as actuators or sensors in numerous respects of our daily life as well as automation lines and industrial applications. Intersection of founding new polymers and composites such as silicon and micro manufacturing technologies performing micro-machining and micro-assembly brings about remarkable growth of application and efficacy of MEMS devices. MEMS indicated huge improvement in size reduction, higher reliability, multi-functionality, customized design, and power usage. Demonstration of various devices and technologies utilized in robotics and industrial applications are illustrated in this article along with the use and the role of silicon in the development of the sensors. Some future trends and its perspectives are also discussed.

For the first time, an annular slot is used to excite the fundamental TM $_{01 \delta }$ mode of a cylindrical dielectric resonator antenna (DRA). The annular slot has eight pairs of meander lines that make the $E$ -field of the slot nearly uniform. The meander lines can introduce an inductance to the antenna and thus, lower the resonant frequency or equivalently reduce the antenna size. To verify the idea, a prototype operating in the fundamental TM $_{01 \delta }$ mode was designed, fabricated, and measured for 2.4 GHz WLAN applications (2.40–2.48 GHz). The ${S}$ -parameters, radiation pattern, realized gain, and total efficiency are simulated and measured, and good agreement between the simulations and measurements is obtained. As compared with a conventional probe-fed TM $_{01\delta }$ -mode cylindrical DRA, our antenna has a size reduction of 43% while providing a measured 10 dB impedance bandwidth of 18.0%.

A novel out-of-plane integration of multilayer strip-resonators is proposed. This kind of structure retains the merit of traditional in-plane integrated ones – simple and compact-sized, meanwhile, achieves the same amount of coupling with smaller horizontal space between resonators. Further miniaturisation of the previous bandpass filters (BPFs) can be realised by re-designing them based on the proposed structure. This Letter gives an example of an S-band BPF. A 52.4% size reduction is achieved by out-of-plane integration of resonators, while maintaining a comparable performance to the previous in-plane integrated design.

In this paper, design process of a new compact microstrip Gysel power divider (GPD) with harmonics elimination is proposed. In the designed GPD structure, two types of resonators are applied to mak...

In this paper, a new substrate integrated waveguide (SIW) structure is introduced. This structure uses some oblique slots on the top surface of the conventional SIW structure. These slots reduce the cut off frequency without affecting the width of the SIW structure. The results show that these slots are non-radiative. A prototype of the proposed structure which is named Fishbone SIW structure, is simulated, fabricated and measured. The measured results show that the proposed structure achieves an insertion loss of 0.7 ± 0.5 dB, return loss of better than 10 dB from 3.2 to 5.4 GHz and size reduction of about 40 % . To further size reduction, the half mode of the Fishbone SIW structure which is named HM-Fishbone SIW structure is designed and fabricated. This structure achieves a return loss of better than 10 dB from 3 to 5.5 GHz and an insertion loss of 0.8 ± 0.6 dB. The measured results of the proposed structures are in good agreement with the simulated ones. The results show the ability of the Fishbone SIW and HM-Fishbone SIW structures in term of size reduction.

The design of a novel differential shorted patch antenna (DSPA) from a normal single-ended shorted patch antenna (SPA) is presented. It is shown that the DSPA has a smaller electrical size than the SPA. A transmission-line model is proposed to explain the reduced resonant size of the DSPA. A size reduction ratio of the DSPA to the SPA is defined and evaluated. It is found that the size reduction ratio mainly depends on the substrate thickness and the patch shape and slightly on the substrate dielectric constant. The simulated and measured results are given for both DSPA and SPA. The size reduction of the DSPA with respect to the SPA was experimentally validated.

A high selective dual band and miniaturized electromagnetic band gap (EBG) unit cell is presented in this paper. The analysis and characterization of the new cell are explained. The modified compact EBG unit cell is based on cutting two inverted U-shaped slots inside the typical mushroom-like EBG. The modified EBG has a 70% size reduction. The dual-band functionality of the structure is confirmed by applying it in a dual-notch ultra-wideband antenna (3.1–10.6 GHz), and the notch frequencies are 5.2 and 5.8 GHz. The dual-band functionality has advantages of a highly selective bandpass between them. The antenna can suppress interference frequencies in less than 100 MHz bandwidth without affecting the antenna performance in the whole bandwidth. Presented results are addressed in terms of circuit modeling, 3D full-wave simulations, and measurements.

In this study, two compact ultra-wideband (UWB) frequency selective surface (FSS) reflectors, which combine the branch loading method with the design of the traditional FSS, are proposed for antenna gain enhancement application. The working mechanism of the proposed FSS reflectors is analysed by the equivalent circuit model. The first FSS reflector, which is a 10 × 10 array with 8.25 mm × 8.25 mm unit size, not only enhances the gain of the UWB antenna, but also guarantees a constant gain with only 0.5 dB variation across the whole operation band. To further reduce the reflector size, a more compact FSS reflector with 6.25 mm × 6.25 mm unit size is designed by printing similar patterns on both sides of a single-layer dielectric slab. Compared to the first structure, the second reflector can realise a 25% size reduction and the same gain variation in the entire UWB frequency range. The only compromise is a 0.5 dB gain decrease. Finally, a good agreement between the measured and simulated results proves the feasibility of the authors' design.

In this article, a Fibonacci circle fractal is inscribed into a circular radiator in order to provide ultra-wideband behavior as well as a 50% size reduction compared to a conventional circular monopole. The third iteration of the Fibonacci series allows the antenna to obtain a steady S11 parameter over the operation bandwidth, going from 2.7 GHz to 14 GHz, an average gain around 1 dB, with a quasi-omnidirectional radiation pattern and a group delay no bigger than 1 ns, suitable for short-pulsed communications.

Fast pace growth in the IC industry is facing the challenges of feature size reduction which in turn demands an alternative to current CMOS VLSI. Quantum-dot cellular automata are emerging as one o...

A smaller microstrip antenna design is essential for current and future wireless applications. For the design proposed in this article, researchers achieved size reduction when a circular microstrip patch is loaded with a metamaterial structure using a complementary split ring resonator (CSRR) with partially loaded nonuniform metasurfaces (NUMSs) on a ground plane. The designed antenna achieved a size reduction of 74% compared to a conventional microstrip antenna. The proposed antenna, resonating at 6.22 GHz, is designed, fabricated, and tested, and the measured results are then compared with the simulations as well as with the designs reported in the literature. The proposed antenna can be used for wireless applications, such as an indoor base-station antenna for vehicle-tovehicle communications.

An antenna element that has not only the self-isolated property but also a compact size is proposed for the fifth-generation multiple-input and multiple-output (MIMO) system in mobile phone applications. In particular, the size reduction is done by introducing two vertical stubs into the original self-isolated antenna element. It is demonstrated that very good isolation and antenna efficiency for an 8-antenna MIMO system can be obtained without using any additional isolation elements or decoupling techniques. An antenna prototype is fabricated and measured; and a quite good agreement between simulation and measurement is obtained.

In this study the effects of using defected ground structures (DGS) composed of a complementary split ring resonator (CSRR) and CSRR with dumbbell (CSRR-D) for rectangular microstrip antennas are investigated. On this aim, two different antennas, which are Antenna B having CSRR etched DGS and Antenna C having CSRR-D etched DGS are designed and fabricated in comparison with the ordinary rectangular patch antenna, which is Antenna A. In both Antennas B and C, CSRR structures are etched in the same position of the ground planes. On the other hand, another ordinary microstrip antenna, called Antenna D, is designed at resonance frequency of Antenna C. For the characterization; resonance frequencies, voltage standing wave ratios, percentage bandwidths, gains, ka values and gain radiation patterns are investigated both in simulations and experiments. The numerical analyses show that 29.39% and 44.49% electrical size reduction (ESR) ratios are obtained for Antenna B and Antenna C, respectively in comparison to Antenna A. The experimental results verify the ESR ratios with 29.15% and 44.94%. Supporting, Antenna C promises 68.12% physical size reduction (PSR) as it is compared with Antenna D. These results reveal that Antenna C is a good alternative for DGS based microstrip electrically small antennas.

This study proposes a simple artificial magneto-dielectric (MD) antenna with a split-ring resonator (SRR) loaded in an array configuration. This SRR element is used to realize the MD characteristic that is beneficial for antenna miniaturization. The simulation of material permittivity and permeability is conducted to ensure that the proposed SRR-array configuration has the expected MD characteristic. Configurations of SRR in arrays of 3×3, 5×5, 7×7, and 9 × 9 are realized to obtain its radiation characteristics when embedded in the antenna ground plane. A rectangular patch antenna is used in this study. Based on the simulation, the proposed antenna with an SRR array of 5×5 achieves excellent MD characteristics with high permittivity and permeability of 32.44 and 51.39, respectively. Furthermore, a microstrip antenna loaded with the SRR 5×5 arrays are fabricated on RT/duroid 5880 substrate. It has a dimension of 0.31λ0 × 0.26λ0. The simulation and measurement results of the proposed antenna show a fractional bandwidth of 4.79% and 5.2% at 1.5 GHz; and a maximum gain of 5.20 dB and 4.95 dB, respectively. Good agreement between the simulated and the measured results was achieved.

In the design of a microstrip power divider, there are some important factors, including harmonic suppression, insertion loss, and size reduction, which affect the quality of the final product. Thus improving each of these factors contributes to a more efficient design. In this respect, a hybrid technique to reduce the size and improve the performance of a Wilkinson power divider (WPD) is introduced in this paper. The proposed method includes a typical series LC circuit, a miniaturizing inductor, and two transmission lines, which make an LC branch. Accordingly, two quarter-wavelength branches of the conventional WPD are replaced by two proposed LC branches. Not only does this modification lead to a 100% size reduction, an infinite number of harmonics suppression, and high-frequency selectivity theoretically, but it also results in a noticeable performance improvement practically compared to using quarter-wavelength branches in the conventional microstrip power dividers. The main important contributions of this technique are extreme size reduction and harmonic suppression for the implementation of a filtering power divider (FPD). Furthermore, by tuning the LC circuit, the arbitrary numbers of unwanted harmonics are blocked while the operating frequency, the stopband bandwidth, and the operating bandwidth are chosen optionally. The experimental result verifies the theoretical and simulated results of the proposed technique and demonstrates its potential for improving the performance and reducing the size of other similar microstrip components.

This paper presents a novel method for the design of truncated microstrip patch antenna with DGS based on Double Looped CSRR arrays for enhancement of bandwidth. The proposed antenna is suitable for WLAN/Wi-Fi, RFID applications. A truncated microstrip patch antenna without DGS was initially designed for a resonant frequency of 2.86GHz having a bandwidth of 95.6MHz. By integrating a new Double Looped CSRR array (DLCSRR) structure on the ground plane, resonant frequency of the antenna is shifted to 2.47GHz and also the bandwidth is enhanced to 202.5MHz. By implementing DLCSRR array structure on the ground plane size reduction and bandwidth enhancement of 52.79% is achieved. The performance of truncated microstrip patch antenna with DGS based on Double Looped CSRR array structure was also compared by replacing conventional proximity fed microstrip patch antenna with the same physical size. The conventional proximity coupled microstrip patch antenna is designed for a resonant frequency of 2.26GHz with a lower bandwidth of 23.3MHz.The antennas were designed using CST simulation software. The measurement result shows a good agreement with simulated results.

We present the design and characterization of a zinc-indiffused periodically poled lithium-niobate ridge waveguide for second-harmonic generation of ∼ 390 n m light from 780 nm. We use a newly developed, broadband near-infrared vertical external-cavity surface-emitting laser (VECSEL) to investigate the potential for lower-footprint nonlinear optical pump sources as an alternative to larger commercial laser systems. We demonstrate a VECSEL with an output power of 500 mW, containing an intracavity birefringent filter for spectral narrowing and wavelength selection. In this first demonstration of using a VECSEL to pump a nonlinear waveguide, we present the ability to generate 1 mW of ∼ 390 n m light with further potential for increased efficiency and size reduction.

This paper presents a reduced size microstrip five poles hairpin band-pass filter using three-layers structure for Ku-band satellites application. The three-layers structure shows a substantially reduced filter size and enlarged bandwidth. The filter has been designed based on five-pole resonators at 12.475 GHz and bandwidth of 550 MHz. This filter is designed on Rogers RO3003 substrate having relative permittivity (εr) of 3. The proposed band-pass filter has been designed with the help of Computer Simulation Technology (CST) software. Comparison analyses between the simulated insertion loss and reflection coefficient of RO3003 and FR4 substrates have been carried out in order to show the efficiency of the proposed filter design. Based on the obtained results, the proposed filter design achieves significant filter size reduction compared to other band-pass filters.

Microstrip patch antennas are widely employed in several applications, thanks to their low profile, low cost, and easy manufacturing. However, the demand for new technologies providing compactness and high performance poses a long-lasting challenge for the antenna designer. Traditional methods for bandwidth improvement and size reduction have some drawbacks, tied mostly to poor radiation performance or troublesome implementation. In this letter, a novel, simple, but effective patch antenna layout exploiting the customizable form factor guaranteed by 3-D printing (or other fabrication techniques) is presented. An appropriate modification in the vertical profile of the radiator is introduced. Specifically, without loss of generality, a cylindrical shape has been selected as a proof of concept. The proposed solution allows to increase the impedance bandwidth from 2.9% of a standard flat microstrip patch to 9%. Additionally, the projected antenna resonant size can be reduced up to 38% compared to its flat counterpart.

Since its first introduction about a decade ago, the halfmode substrate-integrated waveguide (HMSIW) has gained enormous interest from researchers, with particular appeal in the antenna community. This is essentially due to the offered advantage of size reduction compared to a full SIW but more importantly to the intrinsic availability of an open aperture in the basic geometry. A great amount of effort has been spent on investigating this structure?s characteristics and its potential for integrated antenna designs, which can be efficient up to the millimeter-wave range. This article aims to provide a comprehensive snapshot of the literature on HMSIW antennas, including structure variations, analysis methods, and applications. A broad variety of HMSIW antennas covering a wide range of applications are systematically categorized, namely, into traveling-wave antennas, resonant cavity antennas, and HMSIW-fed antennas. Conclusively, the HMSIW is a versatile structure for numerous antenna applications.

A compact filtering Wilkinson power divider with harmonic suppression based on lumped components is presented in this paper. The new divider uses two 5th-order elliptic-function low-pass filters to replace the quarter wavelength microstrip lines of the conventional Wilkinson power divider. The structure combines the power divider and the filter into a complete device. By integrating elliptic low-pass filters with the power divider, the proposed structure can suppress harmonics due to the filter’s band-notched characteristic. The power divider demonstrates a measured suppression of 37.1 dB for the second harmonic, 36.6 dB for the third harmonic, 38.6 dB for the fourth harmonic respectively. The harmonic suppression is higher than 20 dB from 2.75 to 7.035 GHz. Furthermore, lumped components are utilized to achieve improvement on size reduction. Compared with the conventional divider, the proposed structure effectively reduces the size by 77 %. The insertion loss is 3.2 dB at the center frequency (1.45GHz).

We have been witnessing the continuous size reduction in consumer electronics devices with longer battery life. The Application Specific Integrated Circuits allow for integration of multiple electr...

In this paper, a shorted planar elliptical metal antenna (SPEMA) is designed for ultra-wideband (UWB) applications. The shorting strip yields almost 20% size reduction and the impedance bandwidth f...

The paper proposes microstrip low-pass filters (LPF) based on three-dimensional electromagnetocrystalline inhomogeneities (ECI). The calculated responses (AFRs) of quasi-lumped reactive elements based on traditional and ECI structures are compared. AFRs of quasi-lumped ECI-based reactive elements are noticeably close to AFRs of lumped elements. The frequency of theAFR first minimum of ECI-based LPF is three times as large as the similar frequency of LPF based on traditional structures. Combined ECI incorporating the inductive and capacitive elements are also proposed. LPF structures based on single and combined ECI are presented. The calculated and experimental parameters and AFRs of filters are presented that illustrate a significant size reduction and performance improvement in the suppression band as compared to the filter having the traditional structure. The amplitude-frequency characteristics have been calculated using the three-dimensional simulation in the environment of CST Microwave Studio software package.

This study describes an enhanced procedure for electromagnetic-simulation-based miniaturisation of antenna structures. The proposed methodology utilises formulation of the antenna design as non-linear minimisation problem oriented towards explicit size reduction with constraints imposed on the reflection response of the structure at hand. The primary idea is to explore the boundary of the feasible region so as to allow efficient identification of a constrained optimum that ensures satisfaction of the prescribed matching requirements for the structure at hand. The proposed algorithm overcomes the issues related to the standard formulation involving a penalty function approach, where high non-linearity of the objective function in the vicinity of the optimum may lead to finding a sub-optimal design. For the sake of demonstration and verification, three examples of ultra-wideband antennas are considered. In all cases, the proposed methodology leads to smaller footprints and better control of the in-band matching compared to the benchmark algorithm, i.e. gradient-based search with implicit reflection response control through a penalty function approach.

This paper presents a highly linear balanced power amplifier with miniaturised quadrature hybrid coupler for carrier aggregation (CA). The miniaturised quadrature coupler is designed using a novel U-shaped transmission line (USTL) concept to achieve good size reduction. The novel branch-line coupler is used to design a wideband balanced PA. The performance of the balanced PA is compared to a single PA solution. The balanced PA shows better performance with improved matching properties and better electrical stability. There was an increase in saturated maximum output power (Pout) from 8 dBm for the individual PA to 13.41 dBm for the balanced with a power aided efficiency (PAE) of 43.92%. The highly linear balanced PA achieves a 14 dB ACPR reduction and also improves ACPR by 12 dB for non-contiguous and 9 dB for contiguous carrier aggregation.

Tunable and array-based multichannel chip-scale optical transmitter devices have revolutionized the pluggable module telecom market, by enabling excellent performance with great cost and size reduction. In this paper, we report on a novel, four-channel, monolithic widely tunable transmitter device (QUAD) in indium phosphide. This device is based on monolithic integration of four widely tunable externally modulated lasers, with a single output waveguide. The QUAD device is designed to operate at 55 °C, in order to reduce the power consumption of the cooler. A full QUAD module was developed and characterized, demonstrating 10 Gb/s simultaneous operation of all four transmitters, with >30 nm tuning range, and error-free operation. Through system-level experiments, the regenerative nature of the QUAD transmitter has been demonstrated.

Mobile and embedded applications of convolutional neural networks (CNNs) use quantization to reduce model size and increase computational efficiency. However, working with quantized networks often implies using non-standard training and execution methods, as modern frameworks offer limited support to fixed-point operations. We propose a quantization approach simulating the effects of quantization in CNN inference without needing to be re-implemented using fixed-point arithmetic, reducing overhead and complexity in evaluating existing networks’ responses to quantization. The proposed method provides a fast way of performing post-training quantization with different bit widths in activations and weights. Our experimental results on ImageNet CNNs show a model size reduction of more than 50%, while maintaining classification accuracy without a need for retraining. We also measured the relationship between classification complexity and tolerance to quantization, finding an inverse correlation between quantization level and dataset complexity.

In the study, a novel implementation of the coupled-line co-directional (CL-COD) coupler is proposed for the first time, and the wideband realizations are also demonstrated. The CL-COD coupler, which is composed of inductor loaded parallel coupled line and a pair of open-circuited stubs, has the advantages of smaller size and inherent harmonics suppression compared with the traditional λ/4 branch line coupler. Design equations of the single-section CL-COD coupler are derived by the even-odd mode decomposition analysis and a prototype is designed for validation. The experimental results indicate that compared with the traditional single-section λ/4 branch line coupler, the designed single-section CL-COD coupler shows a size reduction of 64.1%, a bandwidth enhancement of 13%, and a second harmonic suppression of more than 20 dB. By cascading multi-sections of the CL-COD couplers, wideband CL-COD coupler with harmonics suppression is also realized. A computer-aided program is applied for solving the circuit parameters of the multi-section cascaded CL-COD coupler. Besides, the two- and three-section cascaded 3-dB CL-COD couplers are designed for guidance. Finally, a 3-dB three-section cascaded CL-COD coupler is fabricated and measured. Compared with the traditional three-section cascaded λ/4 branch line coupler, the prototype shows a size reduction of 61.9% with an additional second order harmonic suppression.

In this paper, a branch-line coupler using closed-loop and open-loop resonators with the operating frequency of 2.69 GHz is proposed. The designed microstrip circuit not only is able to suppress the second and the third unwanted harmonics but also reduces the occupied area to 59% of the traditional branch-line coupler. To explain how the employed resonators can suppress spurious frequencies, transmission zeros of both resonators based on their equivalent LC has been calculated, separately. To prove the abilities of the proposed branch-line coupler, the designed circuit has been fabricated and tested resulting in a good agreement between the measurement and simulation results. According to the S11 when it is less than -15 dB the bandwidth of the designed branch-line coupler is about 500 MHz, from 2.42 to 2.92 GHz .The comparison between the results of simulation and measurement are in good agreement.

This paper presents a new coupler configuration which can be designed with both arbitrary power division and nonstandard phase difference at the output ports. The planar coupler ring is composed of...

This article presents the design and implementation of a Miniaturized 3 dB hybrid coupler with low-cost instant inkjet printing technology. The coupler has a promising potential advantage in applications in antenna beam forming network and feeding networks for phased antenna array. Explicit design equations were derived and used in the design of the coupler. To validate the design procedure, a prototype of the 3-dB coupler was implemented using the low-cost instant inkjet silver-nano printing technology. The responses of the hybrid show that the return loss and isolation are both below −20 dB at the designed frequency. The size reduction of this coupler is 73.7%. However, there is little drop in the bandwidth from that of the conventional coupler. This bandwidth reduction is a payback for the significant size reduction.

In this paper, we propose a novel dual-band coupler based on circular patch structure perturbed with slits, shorting posts and defected ground structures. It is shown that the proposed perturbations allow size reduction and independent control of the operating bands in terms of their position and power-split ratio between the output ports. To demonstrate the potential of the proposed structure, two dual-band 3-dB couplers operating at 2.4/5.2 and 2.4/5.8 GHz have been designed, fabricated and measured. The couplers are characterized by excellent in-band performance and compact size of only 0.41λg × 0.41λg. Additionally, three couplers operating at 2.4/5.8 GHz with different combinations of coupling coefficients at the two operating bands have been designed and fabricated.

A novel optically transparent, flexible, and mechanically reconfigurable zeroth-order resonant (ZOR) antenna using stretchable micromesh structure is presented in this paper. The size reduction of the antenna is achieved by using the ZOR property, and the uniform metallic patches of the antenna are replaced with the tortuous micromesh. The tortuous micromesh structures provide a high degree of freedom for stretching when encapsulated in elastomeric polymers with added feature of semitransparency. Accordingly, the structure can undergo mechanical deformation such as stretching (up to 40%), folding, or twisting without breakage. The resonant frequency of the antennas is linearly reconfigurable from 2.94 to 2.46 GHz upon stretching.

A compact 38 GHz multibeam antenna array is presented for fifth-generation applications. A beamforming network featuring a substrate integrated waveguide (SIW) multifolded 4 × 8 Butler matrix is constructed. Benefiting from multilayer structure, the Butler matrix is highly integrated and assembled underneath the radiators to achieve compactness. The Butler matrix is, then, combined with an 8 × 10 SIW slot-coupled patch array to establish four steering beams along the H-plane and to accomplish size reduction of 53.5% in its longitudinal direction. For demonstration, one prototype of the proposed antenna array was fabricated. The measured four beams point toward ±36° and ±12° with gains equal to 19.8 and 21 dBi, respectively.