Class E power amplifier circuit consists mainly of a transistor operates as a switch, load network and series LC filter tuned to fundamental frequency. There is different configurations to realize class E power amplifier circuit according to the load network such as: shunt capacitance configuration, shunt inductance configuration and parallel circuit configuration. In this paper the performance parameters (such as: PAE, overall efficiency, drain efficiency, gain, drain voltage and current waveforms) of class E power amplifier with shunt capacitance configuration at frequencies [0.25, 0.5, 0.75 and 1 GHz] are observed

This paper presents a synthesizing design of a linear antenna array by adapting the Schelkunoff method. The idea behind this type of design is to produce nulls in radiation pattern of a structure without any notable effects on the main lobe. This design has been undertaken around 9 GHz, where both theoretical and simulation results are achieved and will be the target of this work. X-band searching radar system is considered where sing

Shaping of the conductor or any of the other parts of the patch radiators plays important role in changing the working parameters of this type of antennas. In this work Annular, shape has been introduced on the conductor patch. Different dimensions have been introduced on the annular geometry and with a help of a simulation package obtained results are dependable on for application in microwave frequency ranging from 2.5 GHz to 5 GHz. Encouraging values of Bandwidth have been obtained with reasonable output of return loss

This paper presents the design and simulation of a microstrip array patch antenna operating at 28 GHz for 5G communication with a maximum reflection coefficient of -17 dB, a very wide bandwidth of 1.5 GHz and a high gain of 6.84 dB. A Roger RT5880, which has a dielectric constant of 2.2 and a height of 0.2 mm has been used as a transmission line with an inset feed. Antenna dimensions were calculated and simulated results have been performed and analyzed using CST Microwave Studio Package. Moreover, linear array with 3x1 and 5x1, to provide better gain to reach 13 dB and reducing the mutual effect, was developed using decoupling simple slab techniques.

This research presents patch antenna design that enhances its performance to work in 5G band with: sufficient bandwidth, acceptable insertion loss level and effective gain value. A selective procedure for finding suitable patch height has been undertaken. Parallel to this a technique of inserting appropriate Rectangular back holes in substrate has been also made. A simulation program using recent version of the well-known HFSS has been used for obtaining best of results. Sufficient bandwidth values in the range of (27 - 29.39)GHz with return loss range( -15dB - -33dB) have been obtained with acceptable gain value.

The security of the communication channels has become a hot research topic for the 5G due to the tremendous advancements in wireless communications over the past two decades, including the recent emergence of the fifth generation (5G) in mobile wireless communications, which is anticipated to support extremely large user connections and exponentially increase the wireless services. This paper describes a new approach to the problem of interception of wireless communication channels between the legitimate users. Physical Layer Security PLS is new topic enhancing the secrecy performance of a Single-input-multiple-output (SIMO) system for wireless communication from one base-station equipped by single transmitting antenna to many users equipped by multiple receiving antennas each. The receiving beamforming techniques “with a perfect channel CSI is assumed”, such as Maximum Ratio Combining MRC and Equal Gain Combining EGC is utilized in order to achieve the perfect secure receiving for the legitimate users. A downlink transmission of Multiple-input-Single-output (MISO) has been designed ‘Basestation’ equipped by multiple transmitting antennas and users (legitimate and Eavesdropper) with single receiving antenna can focus the information signal in the direction of the intended/information user while minimizing the signal's quality as received by an eavesdropper. The technique of Artificial Noise AN is also researched in addition to beamforming. The secrecy rate performance measured as Bit-error-ratio BER vs SNR in SIMO system model implemented with the receiving beamforming schemes MRC and EGC suggested that the MRC is considered as an optimal receive beamforming diversity technique in order to achieve a best secrecy rate of transmitted signal and as it was compared to secrecy rate performance resulted from MISO system model

Yagi-Uda antennas are known to be difficult to design and optimize due to their sensitivity at high gain, and the inclusion of numerous parasitic elements. There are various patch antennas used for Wi-Fi and Wi-MAX applications, but with high gain and directionality are requirement. Generally number of directors is raised to increase gain of these antennas. But, here we present modified designs of Yagi-Uda antennas, in which the directivity, gain and bandwidth can be enhanced by different techniques. In this paper initially discuss a design of a conventional Yagi-Uda antenna with four uniform directors is undertaken and uniform spacing between them. Results show that, the proposed techniques would enhance the directivity, gain as well as bandwidth when compared with the first design of Conventional Yagi-uda antenna. Finally, it can be said that the proposed design is suitable for Wi-Fi and Wi-MAX antennas with opertating frequency range starting from 2.45 GHz.

Antennas play very important role in the performance and consistency of any wireless communication system. In this work we have design, investigate, and optimize the various parameters as well as the bandwidth of a multi-band microstrip antenna using different positions of slot patch and defected ground plane structures (DGS) techniques. A Roger RT/ duroid 5880 substrate with dielectric constant 2.2, and ground plane with an area of 80mm×90mm have been chosen for operation at three different frequency bands centered at (2.30-2.7) GHz, (4.0-4.7) GHz and (5.2-5.8) GHz. The operation scope of the proposed structures is intended to work for WLAN, IMT (International mobile telecommunications) and WiMAX applications. Ansoft-High Frequency Structured Simulation package (Ansoft-HFSS) has been used as realization software of the proposed antennas.

In first stage of each microwave receiver there is Low Noise Amplifier (LNA) circuit, and this stage has important rule in minimizing the system noise figure, provide enough gain with sufficient linearity, and assure a stable 50 Ω input impedance at a low power consumption. The design of a LNA in Radio Frequency/Microwave (RF/MW) circuit requires the trade-off many importance characteristics such as gain, Noise Figure (NF), stability, power consumption and complexity. This situation Forces the designers to make choices in the design of RF circuits. In this paper the aim is to design and simulate a LNA circuit with high gain and low noise using E-pHEMT MGA665P8 transistor for frequency of 4 GHz. The amplifier is manually designed using conventional technique, Smith chart was used to do a matching of the input and output of the amplifier. The matching network was designed with microstrip lines and it’s single-stub with minimum lengths. A completed design of amplifier was optimized using Hewlett- Packard Advanced Design System (HP-ADS) software. A single stage LNA has successfully designed with 21.032 dB forward gain and 0.697 dB noise figure and working stably in the desired frequency.

A definition of thermophysiological parameters of the Specific Anthropomorphic Mannequin (SAM) CAD model material is proposed in this paper to calculate the temperaturerise in the head of cellular handset users. The SAM materials have the electrical and thermal parameters based on the averaged properties of a heterogeneous High-Resolution European Female Head (HR-EFH) with twenty five different tissues. The specific absorption rate (SAR) and the temperature-rise in the SAM because of the exposure to radiation of different handset models, i.e., candy-bar with external antenna and candy-bar with internal antenna, are calculated in the GSM900 and GSM1800 using a FDTD-based platform. The computations were also carried out applying HR-EFH for comparison.

A thorough investigation into the effect of the hand-hold position on the electromagnetic (EM) wave interaction of a clamshell-type cellular handset and a human is presented in this paper. A FDTD-based platform, SEMCAD-X, is used to achieve the simulations, where two semi-realistic handset models of different external-antenna attachment positions (left and rightside) are designed with the most parts configuration and operating at different GSM-frequency standards (GSM-900, GSM-1800/DCS, and UMTS/IMT-2000). Moreover, homogeneous and heterogeneous CAD models are used to simulate the user’s head, whereas, a homogeneous model with three different tissues is designed to simulate the user’s hand-hold. The antenna performance, as well as, the specific absorption rate (SAR) in tissues are both examined for different (42) possible cases, where several antenna/hand positions are considered in simulation.

The impact of human head with different originations on the induced SAR owing to the RF emissions of different cellular handset models is intensively investigated in this paper. Four homogeneous head phantoms with normal (non-pressed) ears are designed and used in simulations for evaluating the electromagnetic (EM) wave interaction between handset antennas and human head at 900 and 1800 MHz with radiated power of 0.25 and 0.125W, respectively. The Difference in heads dimensions due to different origins shows different EM wave interaction with cellular handsets.

This paper predicts the effect of the user’s hand-hold position on the Total Isotropic Sensitivity (TIS) of GSM900/1800 mobile phone antennas of realistic in-use conditions, where different semi-realistic mobile phone models, i.e., candy bar and clamshell, as well as different antenna types, i.e., external and internal, are simulated using a FDTD-based platform. A semi-realistic hand model consisting of three tissues and the SAM head are used in simulations. The results show a considerable impact on TIS of the adopted mobile phone models owing to the user’s hand presence at different positions, where a maximum level of TIS is obtained while grasping the upper part of the mobile phone against head. Maximum TIS levels are recorded in talk position for mobile phones with external antenna and maximum differences in TIS levels due to the hand-hold alteration are recorded for clamshell-type phones.

This paper investigates both the computation accuracy (based on the power balance error) and the cost in terms of the number of FDTD-grid cells due to the artifact rotation for a cellular handset close to the user’s head. Two study cases are simulated to assess the EM coupling of a cellular handset and a MRI-based human head model at 900 MHz; firstly, both handset and head CAD models are aligned to the FDTD-grid, secondly, handset close to a rotated head in compliance with IEEE-1528 standard. A FDTD-based platform, SEMCAD-X, is used; where conventional and interactive gridder approaches are implemented to achieve the simulations. The results show that owing to the artifact rotation, the computation error may increase up to 30%, whereas, the required number of grid cells may increase up to 25%

This paper presents a novel cellular handset design with a bottom-mounted short loaded-whip antenna. This new handset design is modeled and simulated using a finite difference time-domain (FDTD)-based platform SEMCAD. The proposed handset is based on a current commercially available bar-phone type with a curvature shape, keypad positioned above the screen, and top-mounted antenna. The specific absorption rates (SARs) are determined computationally in the specific anthropomorphic mannequin (SAM) and anatomically correct model of a human head when exposed to the EM-field radiation of the proposed cellular handset and the handset with top-mounted antenna. The two cellular handsets are simulated to operate at both GSM standards, 900 MHz as well as 1800 MHz, having different antenna dimensions and intput power of 0.6 W and 0.125 W, respectively. The proposed human hand holding the two handset models is a semirealistic hand model consists of three tissues: skin, muscle, and bone. The simulations are conducted with handset positions based on the IEEE standard 1528-2003. The results show that the proposed handset has a significant improvement of antenna efficiency when it is hand-held close to head, as compared with the handset of top-mounted antenna. Also, the results show that a significant reduction of the induced SAR in the human head-tissues can be achieved with the proposed handset

This paper is intended to investigate intensely the impact of multipossible hand-hold positions on the electromagnetic (EM) interaction of handset antennas and a human by using a finite-difference time-domain (FDTD) method. Candy-bar handsets with different external and internal antenna positions operating in the GSM900, GSM1800/DCS, and UMTS/IMT-2000 bands are hereby simulated with configuration of the most parts in order to achieve the commercially available handset model design. Homogeneous and heterogeneous phantoms both are used to simulate the human head, whereas, a semirealistic model with three different tissues is designed to simulate a human hand holding a set. Both of the antenna performance including the total isotropic sensitivity (TIS) and the specific absorption rate (SAR) in tissues are examined for the different suggested applicable cases, where various positions of antenna, handset and hand are considered in simulations. This simulation study determines that both of the antenna performance and the SAR in tissues significantly alter owing to the positioning of the handset against user’s head at different hand levels; where a maximum alteration is observed due to the exposure of handset with internal antenna, as compared with the handset having external antenna.

This paper presents a through investigation into the effect of the external antenna and printed circuit board (PCB) positions in cellular hand-sets on the coupling between the handset and human-head at GSM-900 frequency standard. The antenna performance and the specific absorption rate (SAR) induced in a human head were computed using a Finite Difference Time-Domain based platform (SEMCAD). A numerical correct model of a European female head was adopted and a semi-realistic hand model was designed during the simulation. The results showed that the optimum position for the antenna and PCB in hand-set close to head is the far right-corner for the right-hand users and the far left-corner for the left-hand users, where a minimum SAR in head is achieved.

This paper investigates the impact of the hand-hold positions on both antenna performance and the specific absorption rate (SAR) induced in the user’s head. A cellular handset with external antenna operating at GSM-900 frequency is modeled and simulated using a finite difference time-domain (FDTD)-based platform SEMCAD-X. A specific anthropomorphic mannequin (SAM) is adopted to simulate the user’s head, whereas a semirealistic CAD-model of three-tissues is designed to simulate the user’s hand. The results show that in case of the handset in hand close to head at different positions; the antenna total efficiency gets reduced to (14.5% - 5.9%) at cheek-position and to (27.5% to 11.8%) at tilt-position. The peak averaged SAR1g values in head close to handset without hand, are 4.67 W/Kg and 2.66 W/Kg at cheek and tilt-position, respectively. Due to the presence of hand, the SAR1g in head gets reduced to (3.67-3.31 W/Kg) at cheek-position and to (1.84-1.64 W/Kg) at tilt-position, depending on the hand-hold position.