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.

With the increasing number of mobile phone users, new services and mobile applications, the proliferation of radio antennas has raised concerns about human exposure to electromagnetic waves. This is now a challenging topic to many stakeholders such as local authorities, mobile phone operators, citizen, and consumer groups. Thus, the prediction of exposure map at urban scale is a very important requirement to find a relevant indicator of the real exposure. In this paper, we propose a monitoring solution for electromagnetic field (EMF) exposure based on a numerical modeling of the radio wave propagation radiated by mobile telephony base stations. The accuracy of this tool directly depends on the input data precision, such as location of base station antennas or their radiation pattern, which are often poorly known. These data are therefore refined by an optimization algorithm fed by a lot of information, such as the indication of the received signal strength (RSSI) measured directly from users' smartphones, which are used as probes. Results show that this method significantly improves the precision of unknown data concerning mobile base stations and the accuracy of exposure maps at urban scale.

An electrodynamically rigorous mathematical model of a combined vibrator-slot structure consisting of a narrow radiating slot cut in a rectangular waveguide end wall and several thin impedance vibrators placed over the infinite screen is presented. Numerical results concerning internal and external electrodynamic characteristics of the antennas with optimized structural parameters have confirmed the possibility of constructing the Yagi-Uda combined radiating structures in the microwave and extremely high frequency (EHF) bands.

A novel compact patch antenna with Defected Ground structure (DGS) operating for Wireless applications is proposed and investigated. This proposed antenna generates four separate resonances to cover 3.271 GHz (WiMax), 4.92 GHz (WiFi), 6.35 GHz (Space applications) and 11.04 GHz (Fixed Satellite applications) while maintaining overall compact size of 32 × 32 × 1.6 mm³ using an FR-4 substrate commonly available with a permittivity of ε_r = 4.4. The proposed microstrip patch antenna (MSPA) consists of a square radiator in which a Log Periodic slot is etched out along with square defects on ground surface and a microstrip feed line. The log periodic slot with DGS modifies the total current path thereby making the antenna operate at five useful bands. Structure displays the impedance bandwidth of 8.34% (3.10-3.37 GHz), 2.00% (4.88-4.98 GHz), 14.68% (6.27-7.194 GHz), and 5.41% (10.79-11.39 GHz) with gains 3.25 dB, 0.85 dB, 5.65 dB and 4.47 dB respectively. The antenna performance is analyzed using numerous parametric optimization studies, field distributions, and currents. Excellent agreement is obtained between measured and simulated results.

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.

This paper presents the design and analysis of an on-chip compatible millimeter wave (mmW) antenna concurrently operating at frequencies 60 GHz and 94 GHz. It is quite challenging to design an antenna at mmW frequency due to propagation of surface waves and use of high index Si substrate for system on-chip (SoC) applications. Hence, in this paper a micromachined mmW antenna design using suspended microstrip technology has been proposed for SoC applications. Dual band operation of the antenna has been achieved by reactive loading at the radiating edge. The designed antenna supports the fractional bandwidth of 3.7% & 5% and gain of 7.68 dBi & 8.22 dBi at 60 GHz and 94 GHz, respectively. The results were also compared using two different EM solvers HFSS and CST which were in close agreement. Parametric effects of different substrate and antenna design parameters have also been analyzed. As a proof of concept, a scaled prototype antenna was fabricated and compared with the proposed mmW antenna.

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.

We present an analytical analysis of a metasurface-based ambient electromagnetic energy harvesting system in which the bi-anisotropic particles loaded with a resistor are used. The proposed metasurface composed of an array of bi-anisotropic particles referred to as an electromagnetic energy harvester that can capture the ambient incident electromagnetic wave energy with a radiative to AC conversation efficiency of around 100%. The captured energy by metasurface is delivered to the load. The load acts as the input impedance of a rectification circuit in a rectenna system. The derived optimal polarizable inclusions can be applied to design bi-anisotropic metasurfaces which can be used for electromagnetic energy harvesting. Finally, the optimal dimensions of a typical chiral structure have been calculated to achieve maximum efficiency for circularly polarized propagating waves.

In this work, an elliptical planar monopole Penta band-notched ultra-wideband (UWB) antenna is proposed. Band rejection at 2.4-2.6 GHz IEEE 802.11 b/g/n, 3.3-3.75 Wi-MAX, 3.9-4.2 GHz C-band satellite communication, 5.15-5.85 WLAN, and 7.9-8.4 GHz X-band satellite communication frequencies is achieved by etching slots in the radiating patch, feed line, and ground plane. The effect of the slot length on the notched band is also studied. The proposed antenna has been fabricated and tested. The measured impedance bandwidth of the antenna is 2.15-12.5 GHz, which covers bands of Bluetooth and UWB applications. The peak gain of the proposed antenna is 8 dB and drops drastically at notched bands. The proposed antenna shows good omnidirectional radiation patterns in the passbands.

A low-profile circularly polarized (CP) antenna for a handheld Ultra-High Frequency Radio Frequency Identification (UHF RFID) reader is proposed in this paper. The radiating part on the top substrate is composed of three inverted-F elements rotated 120˚ around the center of the structure. A power splitting circuit, placed on the bottom substrate, based on a series transmission line feed delivers equal amplitude to the three IFA with a sequential 120˚ phase shift. Both layers are fabricated on low-cost FR4 material. This design has a disk form factor with a compact size of 35 mm circle radius and an 8.6 mm height. The measurement shows good results with S₁₁ as lower than -10 dB for the whole band, 3 dB-axial ratio around 110˚ (10 MHz of bandwidth), directivity reaching 4.4 dBic, and the total gain of the antenna is 1.9 dBic. In order to validate the proposed antenna performance, a UHF RFID handheld reader is built based on the ThingMagic M6E-Nano module. Different scenarios are investigated to validate the proposed antenna performance in a real environment.

In this paper, a new monopole compact antenna with tunable frequency fed by a coplanar waveguide (CPW) for WiMAX, WLAN, LTE bands, and X-band satellite communication system is presented. This is achieved by adequate combination of a new radiating patch element along with slots and switches. The simulation and measurement results show that depending on ON/OFF states, the proposed reconfigurable antenna, printed on an FR4 substrate, can operate in four applicable frequency bands, i.e., [2.37-2.75 GHz], [3.15-4.08 GHz], [4.48-5.92 GHz], and [6.69-8.31 GHz]. Very interesting results for the reflection coefficient, current distribution, and radiation pattern of the antenna are presented and discussed. The measured results are in good agreement with the simulated ones.

This work presents the modelling of a highly efficient all-metal slotted waveguide array antenna (SLWA) at sub-THz frequencies for the 5th generation communication applications or beyond. The slotted waveguide array antenna is modified for the accomplishment of high gain, wide bandwidth, and circularly polarized broadside radiation pattern. The proposed double `T'-shaped slot (DTS) which acts as an active element in the whole antenna radiation and other elements after DTS contribute high directivity and gain. The designed slotted waveguide array antenna with DTS is modified for the reconfiguration of linear polarization into circular polarization and achieves the axial ratio (AR) below 3 dB for the bandwidth of 22.323 GHz with a maximum gain of 14.4 dBi. The length and shape of the slot are altered in the SLWA in-order to set up the advanced rectangular stepdown slots (RSDS) and cross stepdown slots (CSDS) for the circularly polarized beam scanning application. The RSDS SLWA, and CSDS SLWA provide wide impedance bandwidths of 56.506 GHz and 61.236 GHz with 3 dB AR range of 12.417 GHz and 9.688 GHz, respectively. The design and simulation of the proposed antenna are done in CST microwave suite and validated using HFSS software.

A low-profile, printed dipole antenna having two feed ports with two parasitic strips for tri-band operation in the 2.4 GHz (2400-2484 MHz), 5.2 GHz (5150-5350 MHz), and 5.8 GHz (5725-5825 MHz) wireless local area network (WLAN) bands is presented. The strip dipole is coupled-fed via a chip capacitor connected to a dual-feed network and generates the 2.4 and 5.2 GHz bands with the aid of the tuning stubs in the feed network. The two parasitic strips are further employed to introduce additional resonance to cover the 5.8 GHz band. It was found that by loading the chip capacitor with proper values between the strip dipole and the dual-feed network, the port decoupling in both the 2.4 and 5.2 GHz bands can be improved, making a dual-feed and yet single antenna system possible. The design with constant strip width is simple in structure and occupies a compact size of 5 mm × 40 mm (about 0.04-λ × 0.32-λ at 2.4 GHz), which is well-suited to current narrow-bezel laptop computers.

In this paper, we present the design and fabrication of a sectoral beam slotted antenna in substrate integrated waveguide (SIW) technology able to achieve a high roll-off sectoral pattern in the horizontal plane and a very narrow beam in the vertical plane, as required in surveillance applications in the band 76-77 GHz. The proposed antenna is designed and fabricated in multi-layer PCB technology, which allows to integrate both the corporate feeding network and the radiating aperture in the same planar and lightweight device. To achieve a remarkable roll-off (> 5.5 dB/deg) and a reduced ripple (< 1.5 dB), the antenna has been designed by synthesizing a sinc-shaped (uniform) aperture distribution along x-direction (y-direction). The synthesis and optimization of so tapered aperture distributions is not easy to be found in the literature, especially for planar devices. A prototype of such an antenna has been fabricated with a horizontal half-power beamwidth (HPBW) of 30˚, by embedding both the feeding network and the radiating aperture in three stacked dielectric substrates. Measurements of the prototype show a fair agreement with numerical simulations.

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.

In a brief but brilliant derivation that can be found in Maxwell's Treatise and traced back to his 1861 and 1865 papers, he derives the force on a moving electric charge subject to electromagnetic fields from his mathematical expression of Faraday's law for a moving circuit. Maxwell's derivation in his Treatise of this force, which is usually referred to today as the Lorentz force, is given in detail in the present paper using Maxwell's same procedure but with more modern notation.

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.

A cosecant-squared radiation pattern synthesis for a planar antenna array by using the genetic algorithm (GA) is presented. GA makes array synthesis flexible to achieve two desired features, namely, low peak side lobe level (PSLL) and small deviation (ripples) in the shaped beam region. In order to obtain a desired csc² pattern with the PSLL constrained, GA optimizes both the excitation amplitude and phase weights of the array elements. Dynamic range ratio (DRR) of the excitation amplitudes is improved by eliminating the weakly excited array elements from the optimized array without distorting the obtained pattern. To illustrate the effectiveness and advantages of GA, the beam pattern with specified characteristics is obtained for the same array by using particle swarm optimization (PSO). Results show that the performances of GA and PSO are comparable when dealing with small-to-moderate planar antenna arrays. However, GA significantly outperforms PSO on large arrays. Moreover, numerical results reveal that GA is superior to PSO in terms of cost function evaluation and statistical tests.