List of articles (by subject) Electromagnetic, Antenna and Propagation
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Open Access Article
1 - A New Switched-beam Setup for Adaptive Antenna Array Beamforming
Shahriar Shirvani Moghaddam Farida AkbariIn this paper, a new spatio-temporal based approach is proposed which improves the speed and performance of temporal-based algorithms, conventional Least Mean Square (LMS), Normalized LMS (NLMS) and Variable Step-size LMS (VSLMS), by using the switched beam technique. I MoreIn this paper, a new spatio-temporal based approach is proposed which improves the speed and performance of temporal-based algorithms, conventional Least Mean Square (LMS), Normalized LMS (NLMS) and Variable Step-size LMS (VSLMS), by using the switched beam technique. In the proposed algorithm, first, DOA of the signal source is estimated by MUltiple SIgnal Classification (MUSIC) algorithm. In the second step, depending on the desired user's location, the closest beam of the switched beam system is selected and its predetermined weights are chosen as the initial values for the weight vector. Finally, LMS/NLMS/VSLMS algorithm is applied to initial weights and final weights are calculated. Simulation results show improved convergence and tracking speed and also a higher efficiency in data transmission through increasing the Signal to Interference plus Noise Ratio (SINR) as well as decreasing the Bit Error Rate (BER) and Mean Square Error (MSE), in a joint state. Moreover, Error Vector Magnitude (EVM) as a measure for distortion introduced by the proposed adaptive scheme on the received signal is evaluated for all LMS-based proposed algorithms which are approximately the same as that for conventional ones. In order to investigate the tracking capability of the proposed method, the system is assumed to be time varying and the desired signal location is considered once in the centre of the initial beam and once in the edge of the fixed beam. As depicted in simulation results, the proposed DOA-based methods offer beamforming with higher performance in both cases of the initial beam, centre as the best case and edge as the worst case, with respect to conventional ones. The MSE diagrams for this time varying system show an ideal response for DOA-based methods in the best case. Also, in the worst case, initial height of MSE is reduced and consequently the required iteration to converge is less than the conventional LMS/NLMS/VSLMS Manuscript profile -
Open Access Article
2 - Wideband Log Periodic-Microstrip Antenna with Elliptic Patches
hamed ghanbari foshtami Ali Hashemi Talkhouncheh Hossein EmamiA broadband microstrip antenna based on log periodic technique was conceived and demonstrated practically. The antenna exhibits a wideband characteristic comparing with other microstrip antennas. Over the operation frequency range, i.e. 2.5-6 GHz, a 50 Ω input impedanc MoreA broadband microstrip antenna based on log periodic technique was conceived and demonstrated practically. The antenna exhibits a wideband characteristic comparing with other microstrip antennas. Over the operation frequency range, i.e. 2.5-6 GHz, a 50 Ω input impedance has been considered. Manuscript profile -
Open Access Article
3 - Theory and Experiment of Parasitic Element Effects on Spherical Probe-Fed Antenna
Javad Soleiman Meiguni Manouchehr Kamyab Ahmad HosseinbeigTheory and experiment of a spherical probe-fed conformal antenna with a parasitic element mounted on a spherical multilayer structure are presented in this paper. Rigorous mathematical Method of Moments (MoMs) for analyzing various radiating spherical structures is pres MoreTheory and experiment of a spherical probe-fed conformal antenna with a parasitic element mounted on a spherical multilayer structure are presented in this paper. Rigorous mathematical Method of Moments (MoMs) for analyzing various radiating spherical structures is presented in this paper by using Dyadic Green's Functions (DGFs) in conjunction with Mixed Potential Integral Equation (MPIE) formulation. Linear Rao-Wilton-Glisson (RWG) triangular basis functions are applied in MPIE formulation. Current distributions on coaxial probe and conformal radiating elements are computed by using spatial domain Dyadic Green's Function (DGF) and its asymptotic approximation. A prototype of such an antenna is fabricated and tested. The effect of the parasitic element on the input impedance and radiation patterns of the antenna is investigated. It is shown that the antenna characteristics are improved significantly with the presence of the conducting parasitic element. Good agreement is achieved between the results obtained from the proposed methods and the measurement results. Manuscript profile -
Open Access Article
4 - Multiple Antenna Relay Beamforming for Wireless Peer to Peer Communications
Mohammad Hossein Golbon Haghighi Behrad Mahboobi Mehrdad ArdebilipourThis paper deals with optimal beamforming in wireless multiple-input-multiple-output (MIMO) relay networks that involves multiple concurrent source-destination pairs with imperfect channel state information (CSI) at the relays. Our aim is the optimization of the MIMO re MoreThis paper deals with optimal beamforming in wireless multiple-input-multiple-output (MIMO) relay networks that involves multiple concurrent source-destination pairs with imperfect channel state information (CSI) at the relays. Our aim is the optimization of the MIMO relay weights that minimize the total relay transmit power subject to signal-to-interference-plus-noise ratio (SINR) of all destinations to be kept above a certain threshold. Since power minimization is a non-convex quadratically constrained quadratic programming (QCQP), we use semi-definite programming (SDP) relaxation of above mentioned problem by using a randomization technique. Numerical Monte Carlo simulations verify the performance gain of our proposed multiple antenna relay system in terms of transmit power and symbol error probability. Manuscript profile -
Open Access Article
5 - EBG Structures Properties and their Application to Improve Radiation of a Low Profile Antenna
Masoumeh Rezaei Abkenar Pejman RezaeiIn this paper we have studied the characteristics of mushroom-like Electromagnetic Band Gap (EBG) structure and performance of a low profile antenna over it. Afterward, a novel EBG surface is presented by some modifications in mushroom-like EBG structure. This structure MoreIn this paper we have studied the characteristics of mushroom-like Electromagnetic Band Gap (EBG) structure and performance of a low profile antenna over it. Afterward, a novel EBG surface is presented by some modifications in mushroom-like EBG structure. This structure, which has more compact electrical dimensions, is analyzed and its electromagnetic properties are derived. Results show that resonant frequency of this novel structure is about 15.3% lower than the basic structure with the same size. Moreover, the novel EBG structure has been used as the ground plane of antenna. Its application has improved radiation of a low profile dipole antenna. The antenna performance over the new EBG ground plane is compared with the conventional mushroom-like EBG structure. Simulation results show that using this slot loaded EBG surface, results in 13.68dB improvement in antenna return loss, in comparison with conventional mushroom-like EBG, and 33.87dB improvement in comparison with metal ground plane. Besides, results show that, EBG ground planes have increased the input match frequency bandwidth of antenna. Manuscript profile -
Open Access Article
6 - SRR shape dual band CPW-fed monopole antenna for WiMAX / WLAN applications
Zahra Mansouri Ramezan Ali Sadeghzadeh Maryam Rahimi Ferdows ZarrabiCPW structure is became common structure for UWB and multi band antenna design and SRR structure is well-known kind of metamaterial that has been used in antenna and filter design for multi band application. In this paper, a SRR dual band monopole antenna with CPW-fed f MoreCPW structure is became common structure for UWB and multi band antenna design and SRR structure is well-known kind of metamaterial that has been used in antenna and filter design for multi band application. In this paper, a SRR dual band monopole antenna with CPW-fed for WLAN and WiMAX is presented. The prototype antenna is designed for wireless communication such as WLAN and WIMAX respectively at 2.4 GHz and 5 GHz. The HFSS and CST microwave studio are used to simulate the prototype antenna for two different FEM and time domain method and they have also been compared with the experimental results. The total size of the antenna is 60mm×55mm×1.6mm and it is fabricated on FR-4 low cost substrate. The antenna is connected to a 50 Ω CPW feed line. Its bandwidth is around 3% for 2.45 GHz (2.4-2.5 GHz) and 33% for 5.15GHz (4.3-6 GHz).Its limited bandwidth in 2.4 GHz frequency is benefit for power saving at indoor application. The antenna has 2-7 dBi gain in the mentioned bands with an Omni-directional pattern. The antenna experimental result shows good similarity to simulation kind for return loss and pattern. Here, the effect of parasitic SRR on current distribution has been studied in presence and absence of parasitic element. The simulation of polarization is confirmed that the antenna has linear polarization. Here comparison between antenna return losses in absence of each parasitic element is presented. Manuscript profile -
Open Access Article
7 - A 2-bit Full Comparator Design with Minimum Quantum Cost Function in Quantum-Dot Cellular Automata
Davoud Bahrepour Negin MaroufiIn recent years, reduction of the complementary metal-oxide-semiconductor (CMOS) circuit feature size has caused significant challenges, such as current loss and leakage, and high power consumption. Therefore, further reduction of the size of CMOS technology is not feas MoreIn recent years, reduction of the complementary metal-oxide-semiconductor (CMOS) circuit feature size has caused significant challenges, such as current loss and leakage, and high power consumption. Therefore, further reduction of the size of CMOS technology is not feasible. Quantum-dot cellular automata (QCA) is an emerging technology at the nanoscale, which can utilize for designing computers and very-large-scale integration (VLSI) circuits in the near future. QCA technology makes it possible to design low-power, high-performance, and area-efficient logical circuits. A comparator function is a digital logical function, which compares whether a bit is greater than, smaller than or equal to the other bit or not (half comparator). Full comparator has a third input, which shows the result of the previous step. Half and full comparators play an essential role in CPU architecture. In this paper, a full comparator circuit based on the QCA and a new quantum cost function is proposed. Besides a 2-bit comparator is presented based on the introduced full comparator. Using the new quantum cost function the proposed full comparator design is compared with the previously presented designs in terms of area, delay, and complexity. Comparisons show that the proposed design has less area and delay and therefore, it is more suitable for utilizing in CPU design. Manuscript profile -
Open Access Article
8 - Standard Deviation Characterization of a Small Size Reverberation Chamber by Using Full-wave Simulation and E-Field Probe
Ehsan Poodineh Farhad Ghorbani Reza Asadi Hadi AliakbarianReverberation Chamber (RC) is a new type of measurement equipment used in electromagnetic compatibility and antenna tests and capable to produce an almost uniform electric filed inside a Working Volume (WV). In this paper, the field uniformity of an actual small size RC MoreReverberation Chamber (RC) is a new type of measurement equipment used in electromagnetic compatibility and antenna tests and capable to produce an almost uniform electric filed inside a Working Volume (WV). In this paper, the field uniformity of an actual small size RC is studied. At first, the mode density of the chamber which should be larger than unity is investigated. In the next step, the Standard Deviation (SD) of a small size RC, as a field uniformity criterion is investigated in an existing RC. A highly detailed three-dimensional model of chamber including its stirrers, antenna, WV, and its door create to verify the field uniformity of a RTS60 reverberation chamber. The removal of reverberation chamber’s stirrers shows that they have a direct effect on the uniformity of field. As the stirrer moves during the test, the effect of three different position of stirrer on the field uniformity is investigated. The transmission antenna, as an important component of these rooms, is simulated and investigated separately. The reflection coefficient of that antenna fit the working frequency band of the chamber. In a real scenario, the SD of the chamber is measured by using an electric field probe. A comparison between the simulation and measurement also is done in order to confirm the uniformity of the electric fields. Manuscript profile -
Open Access Article
9 - Measurement and Analysis of Radiation Levels from Base Transceiver Station in Sambas
Fitri Imansyah Leonardus Sandy Ade Putra Eka KusumawardhaniThe development of telecommunications in Indonesia until now has experienced a very significant increase and has become a significant need in communication. Many people use communication tools daily, causing many providers to set up Base Transceiver Stations (BTS) to re MoreThe development of telecommunications in Indonesia until now has experienced a very significant increase and has become a significant need in communication. Many people use communication tools daily, causing many providers to set up Base Transceiver Stations (BTS) to reach their users to remote areas. BTS has a transmit power that can reach the destination area, but most people still do not know the level of radiation emitted and the health effects on the body. Therefore the International Commission for Non-Ionizing Radiation Protection (ICNIRP) has set a threshold level of safe radiation for the human body. Sambas is one of the cities in West Kalimantan which is the target for the development of BTS establishments by operators. This makes the surrounding community feel afraid of the health caused by radiation from the BTS. So it is necessary to do some research, socialize, measuring, and evaluate the level of radiation emitted from BTS, especially in residential areas. The research was conducted through several stages, including; data collection, data collection methods on variations in distance from BTS, results of radiation level measurements, and comparisons to the safe threshold value for radiation intensity that has been set by ICNIRP. The measurement results from 20 BTS in Sambas show that the radiation level from the BTS measured is still far from the safe radiation threshold that has been set by ICNIRP. Manuscript profile -
Open Access Article
10 - Broadband Low-cost Reflectarray based on a New Phase Synthesis Technique and a Class of Cross Bow-Tie Cells
Mahmood Rafaei-Booket Mahdieh Bozorgi Seyed Mostafa MusaviIn this paper, a class of Bow-tie unit cell on FR4 substrate is designed and investigated to be used in implementing a single-layer broadband Reflectarray Antenna (RA). In the analyzing step, two different parameters (length and angle) of the grounded Cross Bow-Tie (CBT MoreIn this paper, a class of Bow-tie unit cell on FR4 substrate is designed and investigated to be used in implementing a single-layer broadband Reflectarray Antenna (RA). In the analyzing step, two different parameters (length and angle) of the grounded Cross Bow-Tie (CBT) are varied to obtain the phase diagrams. Various degrees of freedom in the CBT structure are very helpful in designing a broadband RA. In the antenna design procedure, an efficient phase synthesis technique is applied to minimize the adverse effects of frequency dispersion causing by the differential space phase delay at different frequencies. This technique optimizes the metallic CBTs arrangement on the aperture of RA, and reduces the dependency of RA design to the CBT’s phase variation. Consequently, combination of the CBT’s phase behavior and the phase synthesis technique leads to designing a broadband RA with a good frequency response. In addition to, the Side Lobe Level (SLL) of the resultant RA is reduced remarkably. For validation of the obtained numerical results, an RA is designed and fabricated in 8.7~12.3GHz frequency bandwidth. The measurements show 27.03 dB as a maximum gain value at 10.2 GHz with a 1.5dB gain bandwidth of 34%. It is also shown that the implemented RA exhibits a reduced SLL (<-18dBi) within its operating bandwidth. Manuscript profile