Anticipated Impact of In-Car Mobile Calls on the Electromagnetic Interaction of Handset Antenna and Human

This paper investigates the impact of the in-car mobile call on the electromagnetic interaction of the mobile handset antenna and user’s head. This impact was evaluated from two different perspectives; First, the antenna performance, e.g., total isotropic sensitivity and total efficiency, and second, the specific absorption rate (SAR) induced in the user's head. A Yee-FDTD based electromagnetic solver was used to simulate a mobile phone in hand close proximity to head at cheek and tilt positions, and working at a frequency of 1900 MHz (GSM 1900/PCS) while making a call inside a car. A Specific Anthropomorphic Mannequin (SAM) was used to simulate the user’s head, a generic phone was used to simulate the mobile phone, a semi-realistic model with three tissues, i.e., skin, bone and muscle, was used to simulate the user’s hand, and a CAD model of Ferrari F430-brand was used to simulate the car. The results showed a considerable degradation in the mobile phone antenna performance while making a mobile phone call inside a car that may drive the mobile phone increases its radiated power to establish a successful connection with the base-station antenna, and consequently increases the induced specific absorption rate in the user’s head

An Area-efficient Microstrip Diplexer with a Novel Structure and Low Group Delay for Microwave Wireless Applications

In this work, a novel structure of a microstrip diplexer consisting of coupled patch cells is presented. It works at 2.5 GHz and 4.7 GHz for wireless applications. The proposed structure is well miniaturized with a compact area of 0.015 λg2, fabricated on 0.787 mm substrate height. It has two wide fractional bandwidths (FBWs) of 28% and 17.9% at the lower and upper channels, respectively. Another feature of the proposed design is the low group delays, which are better than 0.4 ns for both channels. Moreover, the designed diplexer can suppress the harmonics up to 10 GHz. Meanwhile, the insertion losses at both channels are low. The design method is based on proposing an approximated equivalent LC circuit of a novel basic resonator. The information about the resonator behavior is extracted from the even and odd modes analysis of the proposed equivalent LC circuit. Finally, our introduced diplexer is fabricated and measured to verify the simulation results, where the simulated and measured results are in good agreement

Design and Fabrication of a Novel Ultra Compact Microstrip Diplexer Using Interdigital and Spiral Cells

A dual-band bandpass-bandpass microstrip diplexer with very small size and good performance is designed in this work. The proposed diplexer has a novel structure which is introduced for the first time in this paper. In comparison with the previously reported diplexers, it occupies the most compact size of 0.002 λg2 (226.7 mm2), fabricated on 0.787 mm dielectric substrate height. The resonance frequencies of the presented diplexer are located at 0.76 GHz and 1.79 GHz making it suitable for the global system for mobile communications (GSM) applications. It has a wide flat channels with two fractional bandwidths (FBWs) of 41.1% and 50%. Another feature of the proposed diplexer is its ability to suppress the harmonics. It can attenuate the 1st to 7th harmonics. Moreover, it has low insertion losses and low group delays at both channels while the isolation and return losses are acceptable. Finally, the proposed diplexer is fabricated and measured to verify the simulation results, where a good agreement between the simulation and measurement results is obtained

High-Performance Ultra-Compact Dual-Band Bandpass Filter for Global System for Mobile Communication-850/Global System for Mobile Communication-1900 Applications

This work presents a novel microstrip dual-band bandpass filter (BPF) using meandros spirals and patch cells, which is proposed for the first time by this work. It occupies a very compact size of 0.0017 λg2. The proposed filter is designed to operate at Fo1=0.85 GHz and Fo2=1.85 GHz for GSM-850/GSM-1900 applications. In addition to the small size, it has several advantages in terms of wide fractional bandwidths (FBW), low insertion losses and high return losses at both channels. The simulated insertion losses at the lower and upper passbands are 0.05 dB and 0.1 dB, respectively. Another advantage of the proposed BPF of this work is the attenuated harmonics, where it is able to suppress 1st, 2nd, 3rd and 4th harmonics (4.11 Fo1) with -20 dB maximum harmonic level

A Review on the Structure, Application and Performance of the Passive Microstrip Devices

Microstrip technology is widely applied for design and implementation of several communication devices such as filters, diplexers, triplexers, multiplexers, couplers, etc. They are utilized to isolate desired signals and remove disturbing signals. The layout of filters, diplexers and triplexers have two, three and four ports, respectively. Passive filters have at least one pass channel, whereas diplexers have at least two channels to transmit the desired signal, and multiplexers have more passbands with more channels. In order to implement the passive components, first a cell called resonator must be designed. Creativity is very important in resonator design. It must be small and novel to get a better device than previous works. Therefore, the layout of previous reported resonator, used in passive microstrip devices, are studied in this work. There is a fierce competition among designers to miniaturize and increase the device performance. Hence we will investigate them, from the point of view size and performance, in this work. Some diplexers are multi-channel, which are more difficult to design than two-channel diplexers. Therefore, the multi-channel diplexers are less reported than the two-channel diplexers. The design of multiplexers is also very difficult because several channels must be controlled. Hence, they are less designed than filters and diplexers. The diplexers can be bandpass-bandpass or lowpass-bandpass, where the latest is less designed. This is because designing a lowpass-bandpass diplexer needs lowpass and bandpass resonators, whereas the design of a bandpass-bandpass diplexer needs only a bandpass resonator

A New Design Approach for a Compact Microstrip Diplexer with Good Passband Characteristics

This paper presents an efficient theoretical design approach of a very compact microstrip diplexer for modern wireless communication system applications. The proposed basic resonator is made of coupled lines, simple transmission line and a shunt stub. The coupled lines and transmission line make a U-shape resonator while the shunt stub is loaded inside the U-shape cell to save the size significantly, where the overall size of the presented diplexer is only 0.008 λg2 . The configuration of this resonator is analyzed to increase intuitive understanding of the structure and easier optimization. The first and second resonance frequencies are f o1 = 895 MHz and f o2 = 2.2 GHz. Both channels have good properties so that the best simulated insertion loss at the first channel (0.075 dB) and the best simulated common port return losses at both channels (40.3 dB and 31.77 dB) are achieved. The presented diplexer can suppress the harmonics acceptably up to 3 GHz (3.3 fo1 ). Another feature is having 31% fractional bandwidth at the first channel

A Sustainable Paperless Online System (SPOS) for Engineering Quality in Teaching: Koya University as a Case Study

Rapidly advancing computer based technologies offer many possibilities for innovation in educational and administrative assessment tasks which allow for a reliable real time reporting and feedback process. This paper considers the requirements for teacher assessments to become an accurate and reliable process. As a case study, the challenges of implementing such a system at Koya University have been considered. This paper examines how a paperless online system can support faculties' efforts for improving sustainable quality in learning and up-to-date assessment techniques. The proposed sustainable paperless online system (SPOS) uses Google Applications for Education that have been adopted at Koya university as a communications and collaboration medium to enhance its teaching quality. Such a system may enhance security, transparency and ease of use while consuming less time and resources and promoting green practice. The work throughout this paper explains how the initiative is engineered for achieving and monitoring a better quality in teaching

Tissue-like P system for Segmentation of 2D Hexagonal Images

Membrane computing, which is a new computational model inspired by the structure and functioning of biological cells and by the way the cells are organized in tissues. MC has been adopted in many real world applications including image segmentation. In contrast to the traditional square grid for representing and sampling digital images, hexagonal grid is an alternative efficient mechanism which can better represents and visualizes the curved objects. In this paper, a tissue-like P system with region-based and edge-based segmentation is used to segment two dimensional hexagonal images, wherein P-Lingua programming language is used to implement and validate the proposed system. The achieved experimental results clearly demonstrated the effectiveness of using hexagonal connectivity to segment two dimensional images in a less number of rules and computational steps. Moreover, the results reveal that this approach has the potential of segmenting large images in few number of steps

The Use of Camouflaged Cell Phone Towers for a Quality Urban Environment

The widespread use of cell phones has led to cell phone towers being located in many communities. These towers, also called base stations, incorporate electronic equipment and antennas that receive and transmit radiofrequency signals. Along with the towers, used for TV and line of sight microwave communication, the proliferation of these base stations is having a detrimental effect on urban esthetics. It is highly recommended for developing urban areas to consider the problem of these unsightly towers as a form of visual pollution, which increases in parallel with the rise of human population density, and also, the possible electromagnetic field (EMF) hazard due to the existence of the cell phone towers in the residential areas. This paper presents the feasibility of using camouflaged cell phone towers to improve the quality of the urban environment. Cell phone towers disguised as trees might address the visual pollution, while, at the same time, might also mitigate the possible EMF hazard by installing these disguised towers in free spaces, rather than on the roof of buildings, schools, hospitals, etc. The feasibility of implementing such a scenario for a quality urban environment in Koya city is discussed

Design and Performance of Microstrip Diplexers: A Review

The radiofrequency microstrip diplexers are widely demanded nowadays by modern wireless communication systems. Hence, several types of previously reported microstrip diplexers are reviewed and investigated in this work. Microstrip diplexers are three ports devices used for separating desired signals and delivering them through two (or more) different channels. The diplexers are investigated in three categories of dual-channel bandpass-bandpass diplexers, multichannel diplexers, and lowpassbandpass diplexers. The investigated multi-channel diplexers include a number of four-channel, six-channel, and eight-channel diplexers. Due to the hard design process, the number of reported diplexers with more than four channels is limited. The layout structures and theory design methods of the previously reported diplexers are studied. Moreover, their size and performance are compared while some explanations about their advantages and disadvantages are presented. This comparison includes insertion loss, return loss, fractional bandwidths, isolation, selectivity, and gaps between channels