In the letter, a compact dual-band and dual-polarized antenna integrated into textile for wireless body area network (WBAN) dual-mode applications is proposed. A vertically polarized omnidirectional radiation pattern is generated at 2.45 GHz for on-body mode, while a circularly polarized (CP) broadside radiation pattern resonates at 5.8 GHz for off-body mode. The proposed antenna consists of a compact round rigid substrate and a piece of felt with a full ground. On the upper rigid substrate, a center-fed circular patch with two open annular slots is designed to generate CP radiation. Then four pins are introduced to help the outer ring patch generates an omnidirectional radiation pattern of TM01. The performances of the antenna in free space (FS) and on body (OB) are verified. Besides, the bending characteristics of textile materials are also analyzed. The speciﬁc absorption rate (SAR) is simulated, which meets the requirementof the IEEE C95.3 standard. These characteristics make the proposed antenna a good choice for WBAN applications.
The integrated design of 4G LTE and mmWave 5G antennas based on a low cost substrate is proposed for mobile terminals. The 4G LTE antenna is designed along with the millimeter wave 5G antenna element, and this integrated module is mounted orthogonally to cater for smartphone applications. The 4G LTE module consists of two orthogonally placed compact asymmetric coplanar strip (ACS) fed antennas which caters to LTE1900, LTE2300, and LTE2500 bands. ACS-fed antennas operate from 1.8 to 2.7 GHz with a reasonable gain ranging between 1.5 and 2.9 dBi. The mmWave 5G antenna module comprises two compact Vivaldi antennas with wideband operational bandwidth ranging from 23 to 39 GHz. Each mmWave 5G antenna attains 1-dB gain bandwidth of 47.6% indicating high radiation bandwidth across the operating frequency band.Orthogonal pattern diversity is achieved for the usage of smartphone in both portrait and landscape modes. The whole antenna architecture is accommodated to the panel of height 6 mm inside a fabricated three dimensional mobile phone case. Simulated and measured results are presented with technical justification.
A broadband circularly polarized CPW-fed slot patch antenna is presented in this paper. The proposed geometry consists of two unequal L-shaped arms, feeding asymmetrically-shaped slots at two opposite corners to achieve wider circularly polarized bandwidth in stable radiation, without any external polariser. The antenna performance exhibits a wide 3-dB axial ratio bandwidth (3-dB ARBW) of 2.8 GHz, starting from 7.4 GHz until 10.2 GHz, within the 10-dB impedance bandwidth (10-dB IBW) of 3.2 GHz (7-10.2 GHz). Results show a stable radiation in the broadside direction, in which the antenna shows a maximum gain of 4 dBi in bidirectional broadside radiation. The proposed structure occupies a global size of 24 × 22 × 0.25 mm3. The outcomes are achieved making, therefore, the proposed antenna an excellent candidate for performed systems within X band range.
A 16-tupling frequency system for millimeter-wave generation using cascaded arrangement of parallel Mach-Zehnder modulators is presented in this paper. Parallel non-ideal Mach-Zehnder modulators are used to realize a Mach-Zehnder modulator (MZM) with an ideal splitting ratio of 0.5. Hence, parallel MZMs work as a modulator with ultra-high extinction ratio. A 5 GHz radio frequency signal is 16-tupled to 80 GHz with optical sideband suppression ratio of 64 dB and radio frequency spurious sideband suppression ratio of 31 dB respectively. The system has radio frequency spurious sideband suppression ratio ≥ 10 dB for modulation range of 2.79 to 2.86. Further, optical sideband suppression and radio frequency spurious sideband suppression ratios are independent of extinction ratio of MZMs.
Aiming at high torque ripple of switched reluctance motor (SRM) caused by hysteresis tolerance control, this study proposes a new deadbeat control based on an SRM rotation coordinate system. The command current is easily calculated on account of the nonlinear deadbeat current controller. For the voltage control, the redefined voltage vectors and space voltage module are discussed to reduce the switching states. Experimental results exhibit that the proposed method can reduce the SRM torque ripple compared with direct torque control and direct instantaneous torque control. In addition, all the results are carried out on a three phase 12/8-poles SRM.
A flexi electron gun consists of multiple electrodes and can be used to maintain uniform beam current over the life of a traveling-wave tube (TWT). The flexi electron gun consists of dispenser cathode, anode1, anode2 and anode3 in addition to a beam focusing electrode (BFE). In an optimized electron gun, anode1 potential plays an important role in increasing beam current within the same biased condition of electronic power conditioner (EPC) and can be used as a critical parameter to increase current with time when cathode performance (beam current) degrades with time. Geometry, position and bias of these electrodes with respect to cathode provide low perveance electron beam optics to the interaction structure of a TWT. The flexi gun has been modelled in EGUN, developed and integrated with TWT, and simulated results are compared with experiment. This paper presents a detailed investigation of the effect of anode1 on beam current and also presents the cause of large variation of simulated and measured beam currents through back simulation in EGUN.
Rectangular dual-cavity structure is usually used to improve the shielding efficiency of a shielding chamber or to avoid the interference between the internal electronic components of the system. In order to simplify the estimation of the shielding effectiveness for a dual-cavity structure with an aperture array,a hybrid analytical model is proposed based on Robinson's model and Dehkhoda's model. In the new model, the enclosure of cavity and the aperture array are equivalent to a short-circuited waveguide and admittance respectively. Using this hybrid model, shielding effectiveness could be calculated efficiently for a common frequency band. The results of typical examples are compared with simulation examples, and they are in very good agreement. This method provides an analytic solution for designers to speed up the design process of a rectangular dual-cavity structure with an aperture array.
This paper proposes a miniaturized monopole ultra-wideband antenna with single-frequency rejection. The recommended antenna size is reduced from 58 × 54 mm2 to 32 × 54 mm2 by the half-cut method. The bandgap design is achieved by placing a dual mushroom type electromagnetic bandgap (EBG) structure on the side of a coplanar waveguide feeding line. The equivalent circuit and surface current distribution were used to analyze and explain the effects of mushroom-like EBG cells and the principle of the half-cut method. Both the prototype antenna and the proposed antenna have been fabricated and tested. From the measurement results, the proposed antenna exhibits good band-stop characteristics and can reject the wireless LAN interference band (5.2 and 5.8 GHz bands). Furthermore, the proposed antenna has considerable gain over the entire operating frequency band except for the notch band.
In this article, a two-dimensional (2D) unconditionally stable finite-difference time-domain (FDTD) approach is proposed for graphene electromagnetic (EM) device simulation. The weighted Laguerre polynomials (WLPs) are utilized to resolve stability concerns, and graphene is modelled as a thin conductive layer incorporating the surface boundary condition (SBC) in WLP-FDTD scheme. The transmittance of EM signal propagating through two graphene layers is calculated for 0-10 THz to verify the effectiveness of the proposed method. The simulation results agree excellently with the results calculated from the analytical and other numerical models. The proposed SBC-WLP-FDTD method provides an alternative numerical approach to simulate graphene-like materials with improved computing efficiency.
In the letter, a compact dual-band Wilkinson power divider terminated with frequency-dependent complex impedance (FDCI) is proposed, for the first time. It is composed of two sections of coupled lines, two shunt transmission lines and a lumped resistor. By using the coupled lines, the FDCI at two bands can be matched. Further, the design equations for the proposed power divider are derived by using the even-odd mode decomposition technology. For verification, a prototype operating at 1.0 GHz and 1.8 GHz was designed, fabricated and measured with different terminal complex impedances at the two bands. The measured results show that the proposed WPD features equal power distribution, good impedance matching/isolation at two frequency bands.
In this work, a micro displacement sensor based on dual micro-cavities coupled to a photonic crystal waveguide is proposed. The defects are introduced to create a sharp resonance in the structure which makes it useful for detecting micro displacement changes. The sensing principle is based on the change of the output signal transmission with the change of the displacement of a moving part compared to a fixed part of sensor structure. The proposed structure reached a good sensitivity of 9.52a-1.
This paper analyzes the variation trend of transmission coefficients of two electromagnetic interference filters with different structures in different temperature environments. Considering the influence of mutual-inductance between capacitors and temperature on parasitic parameters, we construct a wideband equivalent circuit model of electromagnetic interference filter and calculate the coefficient of the parameter as a function of temperature by measuring the parasitic parameters of common mode chokes (CMC) in different temperature environments. Because the wide range of selected temperature changes, it is necessary to divide the entire temperature range into two temperature segments and calculate the temperature coefficients respectively to ensure the accuracy of the data. Through the simulation and experiment, we have obtained the variation trend of the transmission coefficient of two kinds of structural electromagnetic interference filters under different temperature environments, and the trend shows that the attenuation performance of the filter rises first and then decreases with the increase of temperature, which verifies that the temperature will affect the performance of the filter.
A novel multifrequency printed monopole antenna applied to GSM, WLAN, and WiMAX standards in laptop devices is developed. The novelty of the proposed monopole antenna is the simple design without using any reactive components, expensive substrate, or any additional hardware to operate in multi-band frequencies for laptop applications. It is noteworthy that the dimensions of the proposed antenna structure is only 0.105λ × 0.05λ, at lower resonating frequency 1.8 GHz, thus attaining a height of only 9 mm above the system ground. This antenna mainly incorporates an `F'-shaped strip and a `C'-shaped strip together printed on an FR-4 substrate. The coaxial feeding results in the generation of three bands with measured impedance bandwidth spanned in the range of (1.74-1.87 GHz) in lower band (fl), (2.40-2.50 GHz) in a medium band (fm), and (5.12-6.06 GHz) in upper band (fu). Furthermore, the aforementioned antenna exhibits excellent radiation performances including gain around 4-5 dBi followed by efficiency greater than 80% in all the operating bands. The simulated and measured results are found in good agreement which demonstrates the applicability of proposed antenna for GSM1800/WLAN/WiMAX applications in laptop devices.
A study on the use of non-ionizing and non-thermal millimeter electromagnetic radiation in tumor chemotherapy was conducted. DNA released from sarcoma 45 tumor (tDNA) and healthy rats (hDNA) in water-saline solution was irradiated during 90 min by frequencies at both resonates for oscillations of water molecular structures (at 64.5 GHz and 50.3 GHz) and non-resonance (48.3 GHz). Non-irradiated and irradiated tDNA and hDNA binding constants with anti-tumorous drugs doxorubicin (DX) and netropsin (NT) were studied. The absorption spectra of non-irradiated and irradiated complexes of DNA with DX and NT were obtained by spectroscopic method. From the absorption spectra, binding constants at 290 K, 300 K, and 310 K temperatures have been determined. According to our calculations doxorubicin and netropsin with irradiated DNA form were more stable complexes and much stronger with tDNA irradiated at resonant frequencies: it was observed doxorubicin and netropsin binding selectivity to irradiated tDNA in-vitro experiments. For a DNA irradiation at resonant frequencies of 64.5 GHz and 50.3 GHz the binding constant K to DX and to NT is almost an order of magnitude higher than for the non-irradiated DNA. The obtained data suggest that the irradiation of malignant tumors by non-thermal (ultra-weak intensity) millimeter electromagnetic waves in combination with anticancer drugs may be promising for clinical oncology. The same antitumor effect can be achieved at much lower doses of medicines (considerable dose reduction). This is essential from the point of view of the application of gentle therapies for patients and the reduction of expenses associated with acquisition of expensive medicines.
This paper introduces a new simple-structured dual circularly polarized (CP) antenna design for fifth-generation (5G) front end systems. The antenna configuration consists of a crescent-shaped slot radiator fed by a pair of rectangular 50-Ohm microstrip lines. The antenna is designed on an FR-4 dielectric substrate with an overall size of 48 × 48 × 1.6 mm3 to operate at 3.5 GHz, a 5G candidate band. A wide dual CP characteristics supporting both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) is achieved in the frequency of 3-4.2 GHz. In addition, the mutual coupling (S21) between two ports of the proposed antenna is better than 15 dB. A prototype sample of the proposed design is fabricated and measured to validate the design concept. The antenna offers sufficient efficiency, gain level, and axial ratio bandwidth which make it suitable for different 5G front end applications such as cognitive radio, base station, satellite communications, imaging, and radar systems.
This article investigates the optimal design of a magnetic-planetary-gear permanent magnet (MPG-PM) machine. The key is to develop a design method for the pole shoe thickness, stator outer diameter and coil turns of the MPG-PM machine in such a way that the torque waveform is sinusoidal. The magnetic field distributions is solved by the finite element analysis according to the optimization results. A prototype of MPG-PM machine is used for exemplification in terms of the experiment performance requirement. Both the predicted and measured results are given to illustrate the proposed machine. The theory analysis and the experimental results show that the magnetic circuit of the MPG-PM machine is correct, and the torque satisfies design requirements. It provides reference and application value for developing high performance and low-cost MPG-PM machine.
In this paper, an ultrawide band (UWB) notch antenna with electromagnetic bandgap (EBG) structure for WiMAX and satellite applications is proposed. The proposed design contains an inverted-π model slot and EBG element which create lower and upper notch frequency bands respectively. The designed antenna is fabricated on a Rogers RT/duroid 5880 with the dimensions of 18 mm × 21 mm × 1.6 mm3 which is fed with a 50 Ω transmission line. The proposed antenna has a range frequency from 2 GHz to 12 GHz, in which lower notch covers 3.3-3.7 GHz (WiMAX), and upper notch covers 5.9-6.9 GHz (satellite uplink application). The proposed antenna measured and simulated results are in good correlation. It has good radiation characteristics in the required frequency bands.
A general resonant condition for rectangular waveguide junctions operating in the single mode regime of the main waveguide is formulated based on previously developed mathematical models. We will consider three types of junctions with various side arms: T-oriented semi-infinite waveguide with an impedance end wall, semi-infinite waveguide oriented in line with main waveguide, and infinite perpendicularly oriented waveguide. The main waveguide is coupling with the side arm through a narrow slot, and it has a dielectric inclusion in the coupling region. As a result of the analysis of the resonance characteristics for the indicated types of waveguide devices, the correctness of the application of the general resonance condition is substantiated. The possibility of neglecting the imaginary part of the permittivity of the inclusion material in calculations is confirmed by a satisfactory agreement between the numerical results and experimental data for an isolated inclusion.
This paper presents a hierarchical saliency detector for ship detection in synthetic aperture radar (SAR) imagery. First, the nonlinear anisotropic diffusive process has been adopted to eliminate clutter, while preserving the target edge feature in SAR image. Second, each pixel in the filtered image is assigned to its corresponding super-pixel region via an adaptation of optimization technique. Third, Gamma manifold for feature representation has been presented for the modeling of intensity of all super-pixels in SAR imagery. Fourth, a threshold segmentation method is used to realize ship detection. The proposed method is an automatic detection process without any sliding window. Experimental results accomplished over real SAR images demonstrate that the proposed detection method can achieve a good performance.
This paper presents a dual-band microstrip antenna for Global System for Mobile Communications (GSM) and Worldwide Interoperability for Microwave Access (WiMAX) applications. The split ring resonators structure driven antenna operates at 900 MHz and 3.3 GHz, respectively. Return losses achieved at the two resonance frequencies are 22.26 dB and 18.97 dB, respectively. The proposed antenna is developed on a cost-effective FR-4 substrate with relative permittivity 4.4, tangent loss 0.002, and partial ground plane. The bandwidths of the proposed antenna are 3.01% and 4.26%, respectively. The design and fabrication procedure along with both simulated and measured results are presented and discussed in this paper. Designed antenna delivers good performance and solution for both applications.