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In this paper, a mutual coupling reduction technique using filtering structures between two antennas resonating in adjacent frequency bands is proposed. Two patch antennas resonating at low band (4.8-5.0 GHz, part of 5G Band N79) and high band (5.15-5.35 GHz, part of IEEE 802.11 ax 5 GHz Band), which are close to each other in frequency spectrum, are used as an illustrative example. The decoupling structure consists of two open-loop resonators with filtering function coupled to the feed line on its edges. By loading the filtering structures, the isolation between the two antennas is improved from poorer than 15 dB to more than 25 dB when the reflection coefficients are still satisfactory in their respective operating frequency bands, showing significant improvements compared to the reference antennas where no filtering structures are introduced. The proposed method can be easily applied to either mobile terminal or 5G CPE (Customer Premise Equipment) devices where both 5G and Wi-Fi are installed as well as many other antennas with similar application scenarios.

An autonomous and continuously operating Radio Frequency Identification (RFID) temperature sensor is designed, manufactured, and tested. This sensor is battery-free and can detect temperature threshold crossings for multiple (room-to-cold and cold-to-room) temperature cycles, respectively. The proposed sensor conveys temperature threshold crossings through the controlled switching of its operating frequency within the 902-928 MHz Ultra High Frequency (UHF) RFID band. For the first time, shape morphing cold-temperature reactive Liquid Crystal Elastomers (LCEs), which provide reversible actuation, are utilized. The proposed sensor design consists of a patch antenna with a customized slot. A passive mechanical switch is connected across this slot and provides the frequency switching as it is activated and deactivated. The integration of this switch with the antenna is achieved using a co-simulation method. Furthermore, the cold-temperature reactive LCE triggers the switch when a temperature violation has occurred, thereby switching the operating frequency of the sensor based on temperature changes. Additionally, a high-dielectric constant substrate and a single matching network that operates at two discrete frequencies are used to design our compact frequency-domain temperature sensor. Moreover, based on the RFID platform, this sensor operates effectively in close-proximity to other sensors. Also, is provides identification and temperature information through an autonomous, continuous, and cost-effective design. Therefore, the proposed sensor has the potential for operation in the Internet of Things (IoTs) applications, where large amounts of data is collected from numerous sensors to extract valuable information for the benefit of users, manufacturers, and delivery companies in the virtual domain of the internet. Finally, ANSYS HFSS and Circuit Designer are used for the simulation modeling. The performance of our sensor is validated using measurements and simulations that agree very well.

A novel approach to designing rectenna systems by eliminating the use of a matching network between the antenna and the rectifier is presented. The proposed rectenna consists of a wide impedance bandwidth 8 octagon disks placed at two different layers laying on both sides of a single substrate and backed by a ground plane. A Schottky diode is placed at each layer right at the feeding location without matching network, forming an array of two rectennas. The rectified power is smoothed out using a low pass filter composed of two RF choke inductors for each rectenna. By virtue of the wide impedance bandwidth of the antenna, the measurement results of the rectenna yielded a 50% radiation to DC efficiency at the operating frequency of 2.1 GHz. The rectifiers were then connected in series or parallel to study the effect of the connection type on the rectified output power. Wideband load resistance response and configurable amount of output DC currents and voltages can be realized using certain DC power combining methods.

In this paper, a high performance adaptive digital low-dropout voltage regulator (ADLDO) is proposed for Internet-of-Things (IoT) applications. In the proposed ADLDO, a fully synthesizable adaptive digital controller is designed. It automatically senses load variations and adaptively controls multi-loop architecture to reduce quiescent current, minimize output voltage ripples and achieve fast transient response. The multi-loop architecture with hill climbing reduces the total bi-directional shift registers length which results in the reduced leakage current in the transistor-switch-array (TSA), and improves the recovery time and output DC voltage accuracy. A dithering technique is introduced to eliminate the limit cycle oscillation (LCO) and improve the performance of the regulator. The dynamic frequency scaling (DFS) mechanism is proposed for reducing controller power consumption in steady state. In order to reduce the offset and output voltage error, a dynamic latch comparator is utilized. When the input supply voltage is varied from 0.5 V to 1 V, the measured output voltage ranges from 0.45 V to 0.95 V with 50 mV dropout voltage. The operating frequency is 10 MHz with fast transient response and quiescent current of 350 ns and 3.7μA, respectively. The maximum measured power and current efficiencies are 89.7 % and 99.97 %, respectively, with 1.9 mV output voltage ripples. Measured load and line regulations are 2.2 mV/mA and 9.5 mV/V respectively. The proposed circuit is implemented in 28 nm CMOS process and occupies 0.016 mm2 chip area.

In this paper, a water antenna has been designed to generate tunable orbital angular momentum (OAM) vortex wave. With a revisiting theoretical analysis about radiation characteristic of the shorted ring patch fed by two probes, a frequency dependent single shorted ring water antenna is designed. With the increase of the operating frequency, the single-ring water antenna can radiate the OAM waves with the changeable modes. Furthermore, a dual shorted ring water antenna is proposed. With a tunable feeding network, the OAM waves with the reconfigurable modes including the l = 1, l = 2 and mixed modes can be radiated by adjusting ON/OFF states of the PIN diode. The prototype of the dual-ring water antenna is fabricated and measured. Good agreement between the simulation and the measurement demonstrates that the overlapped bandwidth for three states covers 2.35~2.55 GHz with a good mode purity.

It is common knowledge that wireless power transfer (WPT) systems with multiple transmitters (Txs) and a single receiver (Rx) have robust efficiency against lateral misalignment. However, the unnecessary coupling among Txs in actual multi-Tx WPT systems causes transmission efficiency degradation, and then additional tuning work is required to adjust some system parameters, such as the phase or frequency of Tx sources. Moreover, the frequency-splitting phenomenon caused by over-coupling between the Txs and Rx still occurs in multi-Tx systems. Thus, output power degradation is inevitable in the over-coupled state. In this article, we propose an optimal capacitance tuning method that is applicable to multi-Tx WPT systems. A multi-Tx WPT system tuned with the optimal capacitances, which are obtained from the critical coupling condition between Txs and Rx, not only compensates the inner coupling among Txs but also achieves the maximum output power in the over-coupled state. To verify the validity of the proposed method, we implemented two-and three-Tx and single Rx WPT systems and measured the output power of load with respect to the Rx position along the $x$ - and $y$ -axes. As a result, with the proposed method without any changes in the operating frequency or phase, the systems could deliver higher output power than the conventional phase-controlled system. In particular, with the proposed method, the systems maintained the constant maximum transmission efficiency of 80% in the over-coupled state.

Biosensors antenna can be applied to the human body such as for health monitoring, diagnosis, and treatment. This research proposes a microstrip antenna that is applied for biosensing applications. The proposed antenna operates in the Industrial Scientific Medicine (ISM) band (2.4-2.5 GHz). In this study, the antenna is designed using the proximity coupled feeding technique. The proposed antenna is designed using CST Software. The antenna was fabricated and measured using the Pocket Vector Network Analyzer (VNA) device. The antenna substrate material used is Roger 3010 with a thickness of 1.28 mm. The results of the proposed antenna simulation show that the operating frequency is 2.46 GHz, S11 is -19.76 dB, and the bandwidth is 401.2 MHz. Meanwhile, the results of the fabricated antenna measurements show the operating frequency at 2.5 GHz with an S11 of -21.55 dB. Based on the comparison graph between the simulation and the measurement results, it can be concluded that the fabricated antenna has experienced an increasing shift frequency compared to the simulation results.

An algorithm for calculating root mean square (RMS) values of the currents through the elements of a full bridge LLC DC-DC converter is presented. Equations obtained on the base of State Plane Analysis for operation above the resonant frequency are used. The influence of the tank inductances ratio and the operating frequency is investigated using graphical representation. Computer simulations are performed for verification of the theoretical results.

Design and testing results of I/Q mixer and voltage-controlled oscillator IP-blocks for application in 5G communications are presented. IP-blocks were implemented in a commercial 0.42/0.25 μm SiGe BiCMOS process. The test results demonstrate that designed mixer has a conversion gain of more than 5.5 dB in the operating RF frequency range from 25.5 GHz to 26.5 GHz and IF frequency range from 1 GHz to 2 GHz, power consumption less than 235 mW. The designed voltage-controlled oscillator has an operating frequency range from 20.8 GHz to 24.6 GHz in the control voltage range from 0 V to 4 V, the output power is not less than 6 dBm, power consumption is less than 116 mW.

In a conventional passive balancing system for the Li-Ion battery, the drained current is determined by the installed bleeding resistors, which are fixed by a constant resistor. The fixed drained current may not support the increased demand for bleeding power when the Li-Ion cells age. An advanced cell balancing circuit should possess the ability to adjust the drained current to support the increased unbalanced SoC among the aged battery cells. The pulse width modulation (PWM) switching technique can be applied to control the duty cycle of the bleeding switch and, consequently, to regulate the averaged bleeding current. The bleeding current can be controlled by adjusting the duty cycle of the PWM switching from 0 to 100 percent of the maximum drained power. The passive balancing circuit controlled by PWM technique will be typically designed with a relatively high maximum bleeding current (low bleeding resistance) in order to obtain the highest flexibility in controlling the bleeding current. Under the requirements of high bleeding current and the ability to control the bleeding current using the PWM technique, this paper discusses technical challenges and design consideration of the passive balancing circuit, i.e. operating frequency and balancing MOSFET switch behavior. As an output of this paper, a design guideline for implementing the passive balancing circuit with the capability of bleeding current adjustment for the Li-Ion battery is suggested.

The results of the theoretical study of the influence of grating thermal expansion on the clinotron radiation frequency has been presented and compared with the experimental data. The external system controlling a chiller for the clinotron grating temperature stability has been developed and tested. The experimental study showed the effective tuning and control of the operating frequency of the Clinotron tubes by varying the cooling water temperature.

This paper presents a technique to compensate the intrinsic loss of a tunable resonator, which can then be used to realize tunable bandpass filters (BPFs) with reduced insertion loss (IL). The parasitic losses in a tunable resonator can be compensated by introducing a negative resistance to the resonator through parametric amplification. Based on the proposed technique, a third-order tunable BPF operating between 1.5 to 2 GHz is designed and simulated. The simulated results indicate that the intrinsic loss can be compensated at each operating frequency. The compensated intrinsic losses are 11.9, 9, and 7.2 dB at 1.5, 1.75, and 2 GHz, respectively. In addition, the resulted noise figure, out-of-band rejection, and return loss are all improved when the parametric amplification technique is applied.

Time-modulated rotationally symmetric circular array (TMRSCA) is designed and synthesized in this paper. All the elements are distributed over the Q annular sectors and controlled by Q high speed RF switches, respectively. The element number in each annular sector, the specific time sequences, and the element positions are optimized by the improved harmony search (ImHS) algorithm for the sidelobe level (SLL) suppression at the operating frequency. An example is presented and the numerical results are compared with several previously published solutions, which illustrated the potential advantages of TMRSCA in time-modulated circular planar array design.

Operating frequency of class E power amplifier with $\pi$ network is analyzed. Based on principle of class E, theoretical analysis shows that perating frequency is adjustable, waveform of current and voltage across switch is shown in time domain.

A multi-band metasurface has been proposed. Simulated and experimental absorption characteristics of the designed metasurface are studied. We demonstrate that the proposed metasurface can realize multi-band resonant absorption and high quality factor. The refractive index sensing performance of the metasurface is also investigated. The results show that the operating frequency of resonant absorption peaks shifts linearly with the refractive index of analytes increasing, which indicates that the designed multi-band metasurface can be applied for refractive index sensing.

The discovery of a new material is usually accompanied by breakthroughs and developments in many other fields. In order to quantitatively evaluate the improvement of electronic power technology by SiC, this paper selects the maximum working frequency as the physical quantity to evaluate the advanced degree of electronic power devices. Through theoretical analysis, an equation for estimating the maximum operating frequency of the circuit is derived. On the hardware platform, the validity of the formula is verified by the comparative experiments of control variables. At the end of the paper, the maximum working frequencies of SiC-based MOSFET and Si-based MOSFET are measured by experiments, and the improvement of electronic power technology by SiC is evaluated quantitatively.

In this paper, a characteristic mode (CM) analysis of a Koch fractal dipole antenna is presented. First, a CM analysis and full-wave EM simulation of a conventional dipole antenna are discussed. A Koch fractal structure is used and optimized for the required operating frequency to reduce the profile of antenna. For multiple iterations of the fractal geometry, CM analysis is performed and compared with the full-wave EM simulation. The Koch fractal dipole is used for the overall profile reduction of the straight dipole antenna. The size of the Koch fractal dipole antenna is reduced by around 10% compared to a straight dipole at 2.4 GHz. It is observed that the result obtained from the CM analysis agrees with the results obtained from full-wave EM simulation.

Improvement of smart cities functioning models use a variety of modern technologies, such as the Internet of Things (IoT) and complex systems for merging and processing large data aimed to make decisions on safety, security and better quality of life. An important point of different systems modelling is taking into account the technology pros and cons and, where possible, combining technologies to reduce the human-harmful effects and gain more benefits from all them. This article proposes method for smart cities transport development based on the IoT concept. For ground and air vehicles detection it is proposed to use the forward scattering (FS) effect principle. This effect is the basis of forward scattering radars (FSR) and can be applied to detect moving objects in the multi-sensor network of the IoT. An example of vehicles detection using a GPS-FS system is used in the article. The hypothesis of the study is that the increase in the number of the IoT sensors in the future as well as their operating frequency will allow the detection of relatively small mobile objects. Also, the proposed method for vehicle detection and classification will not pollute the radio with additional signals because it will use only the available ones. This technology also benefits the protection of the environment from radio pollution.

This paper presents the results of two methods of improving the radiation characteristics of a Vivaldi antenna in phased array. The effect of cutouts and rectangular inserts along sides of antenna are showed. The biggest improvements were obtained using inserts. They allow enlarging the operating frequency band of the radiator on the level of VSWR less than 3 expand from the range from 327 to 840 MHz to the range from 245 to 857 MHz. The overlap ratio was increased from 2.57 to 3.5. These results were obtained with scanning mode in the E-plane in the sector of angles up to ± 60°.

The method of lowering the minimum operating frequency of a linear antipodal Vivaldi antenna array is proposed. Improvement of frequency characteristics is achieved by using antipodal Vivaldi antennas, in which the transition from the double-sided parallel-strip line to asymmetric double-sided slot line is made in the form of a sinusoid. Simulation results of a linear antenna array made of proposed elements are presented. A comparative analysis of the simulation results with the characteristics of similar antenna arrays of conventional antipodal Vivaldi elements is carried out. Experimental results of VSWR dependencies for a single proposed element are presented.

This paper presents design and results of modeling a subarray of a multibeam antenna array with a co-phased power scheme. The proposed subarray is a linear array of four printed dipole antennas with a horn-shaped reflector, and a power circuit based on a four-channel strip power divider. Its operating frequency band on the level of VSWR less than 2 is in the range from 2.00 to 2.32 GHz. The realized gain is in the range from 12.0 to 12.5 dB.

Inductive power transfer (IPT) technology has been extensively studied for electric vehicles (EV) in the past decades. However, it has not drawn much attention in railway application. Due to the unique requirements of the railway system, most of the EV coupler designs are not directly compatible with wireless charging applications for a train. To fill this technical gap, this paper discusses the design considerations for railway application and introduces a design of a modular 5-kW IPT system for rail locomotives. According to the design constraints, a novel W-I coupler is proposed for the 5-kW IPT system and the system is optimized via ANSYS Maxwell. A prototype of the proposed IPT system is developed at an airgap of 5 inches and 85 kHz operating frequency. The prototype has been validated in a 1.7 kW output power supply with a DC to DC efficiency of 85.6%. The experimental results validate the feasibility of the IPT system design for rail application.

The previously proposed resonance-based reflector (RBR) antennas have the merits of wide impedance bandwidth, low-profile, and unidirectional pattern; however, their front-to-back ratio (FBR) bandwidths are narrow. In this paper, a wideband RBR is proposed for FBR bandwidth enhancing antenna with a low profile. The proposed RBR consists of a metallic ring with three stubs printed on a substrate. It has a ±90° in-phase bandwidth of 63.57% (3.23-6.24 GHz) and its reflection magnitude values range from -0.02 to -11.5 dB within the in-phase band (-90° L at the lowest operating frequency, and the RBR has the same size as the bowtie antenna. Compared to the previous RBR antennas, the proposed RBR antenna has wider FBR bandwidth. The operating band of the antenna is suitable for 5G system applications.

Over recent years, the memory effect compensated digital pre-distortion (DPD) has been widely used for linearizing wideband radio frequency power amplifiers (RF-PAs). However, with the increase of memory depth, the DPD model becomes more accurate, but the computational complexity of the DPD is significantly increased. In this paper, an approach using the attention mechanism is proposed, which can be used for locating and eliminating the memory terms with a small contribution to the performance of the DPD model so that the complexity of the DPD model is significantly reduced. The attention mechanism is employed to obtain the weighted correlation coefficient matrix of the memory effect. And the memory terms in the DPD model will be retained only if the contributions are high, which are evaluated by ensemble averaging over each diagonal of the weighted correlation coefficient matrix. To verify the applicability of the approach, a three-carrier wideband code-division multiple access signals with a bandwidth of 15 MHz and a single carrier long-term evaluation signal with a bandwidth of 20 MHz are employed for testing two Doherty RF-PAs with an operating frequency of 460 and 1900 MHz. Moreover, the generalized memory polynomial model is used to verify the effectiveness of the proposed approach. The simulation and experimental results show that the modeling accuracy and the DPD linearization performance of the DPD model with and without the memory term reduction are all almost the same, which indicates the effectiveness of the proposed approach.

Proposed is an advanced integer division algorithm wherein divisor is a constant. It is to be used in Gaussian filtering module of FPGA based Canny. The algorithm is explored for mathematical accuracy, maximum operating frequency and minimum number of clock cycles on the basis of ten Intel (Altera) FPGA families.

The variation of rain effects for terrestrial communication are examined at frequencies above 10 GHz in the present study. Propagation parameters like attenuation coefficient and phase-delay coefficient are assessed for the rain filled medium. It is examined how the pulse is distorted while passing through rain cell. Specific attenuation is computed at different frequencies from 10 to 70 GHz and rain rate from 5 to 245 mm/hr for horizontal and vertical polarization. The effects of rain rate, the operating frequency and the propagation path length on the rain attenuation are tested. The impact of polarization type on terrestrial rain attenuation is examined here.

Currently, there is an acute problem of detecting small-sized unmanned aerial vehicles (UAVs) to prevent unauthorized access to protected objects. The article discusses modern methods for detecting miniature and microminiature UAVs, their implementation features, advantages and disadvantages. A comparative analysis of existing and promising methods for constructing a detection system is presented. The authors propose an active acoustic method for detecting miniature and microminiature UAVs. This method is based on the estimation of Doppler frequency shift and amplitude change using ultrasonic wave as a probing signal. Preliminary tests have shown its performance at distances up to 15 meters using a continuous wave ultrasound at a operating frequency of 20 kHz and a radiation power of 0.3 W. An ultrasonic piezoceramic transducer is used as a transmitting and receiving device. The results of the comparative analysis allow promising research for the development of a detection system for miniature and microminiature UAVs.

In this paper, a Hetero-junction Vertical Trench MOSFET (HVTFET) is proposed. The HVTFET has a multilayer structure. Compared with FinFETs and GAAs, the HVTFET provides a new method to effectively overcome the DIBL effect of the small-size IC. The channel length L ch of HVTFET is determined by the thickness of the epitaxial channel region, so the L ch can be reduced greatly, therefore the operating frequency of the HVTFET can be greatly increased. The HVTFET can achieve higher V dd by increasing the length of the low-doped drain region or reducing its doping concentration. The 7nm HVTFET simulation model has been established by using Sentaurus TCAD and it can work normally. The HVTFET breaks though the traditional IC reduction rule, and the HVTFET will lead IC to move forward in the future.

In this demonstration, we present AB9 SoC system, a single-chip solution for AI application. It provides the reconfigurable and programmable architecture to support the general computations for a variety of neural networks. The AB9 SoC is implemented using TSMC 28-nm process technology with a chip size of 17×23 mm2 and 1GHz operating frequency.

A recurrent neural network (RNN) is presented in this work for automatic detection of atrial fibrillation from raw ECG signals without any hand-crafted feature extraction. We designed a stacked long-short term memory (LSTM) network - a special RNN with capability of learning long-term temporal dependencies in the ECG signal. The RNN is digitally synthesized in 65nm CMOS process, and consumes 21.8nJ/inference at 1kHz operating frequency, while achieving state-of-the-art classification accuracy of 85.7% and f1-score of 0.82. The energy consumption of the proposed RNN is 8 χ lower than state-of-the-art integrated circuits for arrhythmia detection.

This manuscript presents a Compact right-left handed (CRLH) structure based hybrid coupler. It consists S-shaped slot, loaded on each quadrant of circular patch hybrid coupler and via at the centre to provide compactness. The proposed coupler provides coupling level 0.1 dB at resonating frequency 3.2 GHz. It provides 3 dB fractional bandwidth of 25% from 2.7 GHz to 3.5 GHz. Proposed coupler provides return loss of 19.0 dB with isolation value of 25.0 dB at operating frequency. The size of designed structure is $0.17\lambda_{0}\times 0.14\lambda_{0}(16.0\ \text{mm}\times 13.6\ \text{mm})$ at frequency of 3.2 GHz, which provides compactness. An equivalent lumped circuit model has obtained and its response having good agreement with EM simulated result. Parametric study has supported out to demonstrate the flexibility of designed hybrid coupler.

In this paper, the mantle cloak antenna was developed to reduce the mutual coupling at a close frequency with the operating frequency of the antenna. The mantle cloak antenna using strip conductors and the mantle cloak antenna using composite right/left-handed (CRLH) structures were designed. By using the mantle cloak antennas, it confirmed that the stopband frequency was 750 MHz, and the antenna characteristics could be maintained at 720 MHz. The mantle cloak antenna using CRLH structures was prototyped and measured to validate the simulation results. The measurement results were found to approximately agree with the simulation results.

The reactance-to-reactance transformer (RRT) technique is proposed in this paper for applying in the tuning circuit to miniaturize the tuning stub. These associated RRT formulas are derived based on conjugately characteristic-impedance transmission line (CCITL) equations and the ABCD parameters. The proposed RRT analytical formulas are applied to both short- and open-circuit tuning stubs. Then, the physical length, electrical length and reflection coefficient are observed at the operating frequency of 2.4 GHz. Simulation results prove that the proposed RRTs can be applied to shorten the tuning stub length compared to that of the conventional single stub tuning.

The radiophysical installation designed to study the effect of microwave radiation on biological objects, with an operating frequency of 915 MHz, was used to influence mice with Ehrlich ascites carcinoma. The laboratory animals were exposed to microwave EM radiation of different intensity. The experimental results obtained revealed the dependence of the tumor growth on the intensity of the microwave radiation exposure.

Controlling the scattering of light or electromagnetic waves are conventionally realized based on the different phases profile of metasurfaces elements. However, this approach is limited to the operating frequency bandwidth and cannot achieve such functionality as frequency beam-scanning. Here, we present a concept of space-modulated metasurface in which the structure is making up with the non-resonated elements. We show that the design can achieve both frequency beam-scanning and fixed-frequency beam-scanning. Also, it provides a large operation bandwidth comparing to the conventional metasurface-based resonating structure. Finally, we fabricate the sample, and the measured responses show reasonable agreement with the simulated results.

A modified monopole element printed quasi-Yagi antenna (PQYA) for bandwidth (BW) improvement is investigated in this paper. With the rectangular driven monopole element, offset feed, and optimizing other design parameters, an operating frequency range from 1.31 to 2.76 GHz is achieved. The evolution steps of the modified monopole element PQYA are presented, and it is shown that an impedance BW can be improved from 41.68% to 71.88%. To verify the simulations, the prototype of the antenna is fabricated and tested. The experimental results are in good agreement with simulated results.

This paper presents a defected metasurface for efficiency enhancement of wireless power transfer localization. To examine this study, the WPT system composes of large Tx small Rx and 5x5 metasurface, which is designed at the operating frequency of 13.56 MHz. Simulated results show that the efficiency of WPT with defected metasurface of 38% when the Rx is placed at the corner unit cell metasurface. Such efficiency result equal the uniform metasurface case with Rx at center.

The accurate operating frequency of Piezo transducers depends highly on a matching resonant network for the transformer coupled self-oscillator. However it is found that the magnetizing inductance of transformer, forwarding nonlinear gain and even power source probably have important effects on the prediction of the oscillating frequency. Thus, this paper introduces the descriptive function to model the transformer coupled self-oscillating driver for Piezo transducer, and analyze the operating frequency and its change. The reasonability and feasibility of the presented analysis procedure are verified by simulation and experiments based on a Piezo power driver prototype.

In this paper, the impact of dielectric insertion on the performance of quad-ridged horn antenna (QRHA) is investigated. The dielectric material which is inserted into the QRHA is aimed to enhance the performance of QRHA, in particular, the bandwidth response with an extension into the lower operating frequency. To achieve the optimum performance, four kinds of dielectric material with different relative permittivity are utilized. The used dielectric materials are Teflon, Paraffin, Epoxy, and Duroid with the relative permittivity of 2, 2.26, 4, and 6, respectively. The characterization results show that Teflon could exhibit better performance than other dielectric materials yielding the bandwidth response of 11.5 GHz in the frequency range of 2.5 GHz to 14 GHz. Meanwhile, the bandwidth response of QRHA without dielectric insertion is 9.6 GHz in the frequency range of 4 GHz to 13.6 GHz.

In this paper, we proposed a deep neural network (DNN)-based estimation of efficiency enhancement by an intermediate (Int) coil in automotive wireless power transfer (WPT) system. The Int coil can enhance the efficiency in the WPT system with the proper resonant frequency of the Int coil. The previous study has explained the resonant frequency of the Int coil should be higher than the operating frequency. According to the resonant frequency of the Int coil, we can achieve the amount of efficiency enhancement. Therefore, the design of the Int coil is essential for optimize the efficiency enhancement of the automotive WPT system. However, it is impossible to achieve the optimize results of efficiency enhancement by simulations. The proposed DNN-based estimation method can predict the amount of the efficiency enhancement in real cases consisted of ferrites and shielding structures.