ACES Publication Search
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| Title: | ACES Journal January 2014 Full Issue |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 15617 KB |
| Title: | ACES Journal January 2014 Front/Back Matter |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 24 KB |
| Title: | Finite Difference Time Domain Modeling of Sub-Wavelength Structured Anti-Reflective Coatings |
| Abstract: | The finite difference time domain (FDTD) method was used to model anti-reflective properties of a variety of sub-wavelength structures for 300 nm to 1300 nm input light. Light hitting non-tapered nanostructures exhibited interference patterns similar to thin film antireflective coatings (ARCs), increasing the antireflective effect at several wavelengths. The lowest reflectance was observed with conical and pyramidal nanostructures with bases of 100 nm or 200 nm and heights of 400 nm or 800 nm. |
| Author(s): | K. Han, H.-Y. Han, J. Stack Jr., C.-H. Chang |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 3972 KB |
| Title: | Incorporation of The Nihility Medium to Improve The Cylindrical Invisibility Cloak |
| Abstract: | Two dimensional cylindrical wave expansion method is used to analyze the cylindrical invisible nihility cloak. Ideal model of the cloak is set up to solve the problem and it is observed that a perfect equivalence with the ideal situation of the cloak can be achieved by using nihility medium at perturbed void region of the geometry. Also it is observed that the use of nihility medium at ?, the convergence rate is independent of the type of incident field. Both the transverse electric (TE) and transverse magnetic (TM) cases have been discussed. |
| Author(s): | A. Shahzad, S. Ahmed, A. Ghaffar, Q. A. Naqvi |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 302 KB |
| Title: | A Novel WCS-SFDTD Method for Solving Oblique Incident Wave on Periodic Structures |
| Abstract: | In this paper, a novel weakly conditionally stable spectral finite-difference timedomain method is proposed to solve oblique incident wave on periodic structures, namely NWCS-SFDTD. Because the stability condition is determined only by one space discretization, this new method is extremely useful for periodic problems with very fine structures in one or two directions. By using the constant transverse wavenumber (CTW) wave, the fields have no delay in the transverse plane, as a result, the periodic boundary condition (PBC) can be implemented easily for oblique incident wave. Compared with the alternating-direction-implicit SFDTD (ADISFDTD) method this NWCS-SFDTD method has higher computational efficiency and better accuracy, especially for larger time-step size case. At each time step, it only needs to solve four implicit equations and four explicit equations, which is six implicit equations and six explicit equations in the ADI-SFDTD method. So while maintaining the same size of the time-step, the CPU time for this method can be reduced to about two-thirds of that for the ADI-SFDTD method. Numerical examples are presented to demonstrate the efficiency and accuracy of the proposed algorithm. To reduce the numerical dispersion error, the optimized procedure is applied. |
| Author(s): | Y.-F. Mao, B. Chen, X.-X. Yin, J. Chen |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 1006 KB |
| Title: | Efficient Analysis of Multilayer Microstrip Problems by Modified Fast Directional Multilever Algorithm |
| Abstract: | Fast directional multilevel algorithm (FDMA) combined with quad-tree structure is presented for analyzing multilayer microstrip problems. This method is successfully applied to analyze scattering in free space and it is extended to solve multilayer mircrostrip problems in this paper. The quad-tree structure is employed for the layer containing the microstrip patch, and then the defined of far field for every observed group is modified. There is only Kernel evaluation in low rank representation so that the surface-wave is extracted for the far-field Green’s functions expansion when the dielectric substrate is thick or relative permittivity is large. The memory requirement and the CPU time per iteration of the multilayer microstrip structure is presented, which show the accuracy and efficiency of this method. |
| Author(s): | H. Chen |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 692 KB |
| Title: | Convex Optimization Based Sidelobe Suppression for Adaptive Beamforming with Subarray Partition |
| Abstract: | This paper proposes a convex optimization based method to suppress sidelobe in adaptive beamforming at subarray level. Usually phase shift rather than amplitude tapering is implemented at element level to maximize signal to noise ratio. Nevertheless, sidelobe control can be realized at subarray level. The proposed approach is realized by adding a constraint minimizing the difference between weights at subarray level and element-level Chebyshev synthesis into the optimal conditions. Compared with penalty function method, simulations show that for a uniform linear array, the proposed method can suppress sidelobe level considerably, especially the lobes close to mainlobe. Furthermore, it is able to produce better shaped main lobe, which is extremely close to the referenced pattern. |
| Author(s): | S. Xiaofeng, X. Jia, Z. Ying, K. Ling |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 490 KB |
| Title: | Optimum Design of Conformal Array Antenna with a Shaped Radiation Pattern and Wideband Feeding Network |
| Abstract: | In the present work, a circular conformal array with wideband printed dipole antennas and wideband feeding network has been designed to obtain a fully constrained cosecant squared radiation pattern using particle swarm optimization (PSO) algorithm and mutual coupling compensation. Using the circular conformal design leads to a decrease of around 33% of the length of the array antenna compared with that of the vertical linear array. Moreover, a better performance of the coverage region and side lobe fall after this area obtains by using this configuration. |
| Author(s): | M. H. Rahmani, A. Pirhadi |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 1073 KB |
| Title: | A Tri-Band Antenna for Wireless Applications using Slot-Type SRR |
| Abstract: | A tri-band microstrip-fed slot antenna for WLAN/WiMAX applications is proposed and investigated. Three operating bands are obtained by inserting split ring resonator (SRR) slots for band-rejected design. An electromagnetic (EM) model of this antenna is simulated by Ansoft HFSS. The principle of operation and parametric of the proposed antenna are also provided. The measured -10 dB bandwidth for return loss is from 2.39 GHz ? 2.48 GHz, 3 GHz ? 3.7 GHz, and 5 GHz ? 7 GHz, covering the WLAN (2.4/5.2/5.8) and WiMAX (3.5/5.5) bands. The proposed antenna achieves a stably omni-directional radiation pattern and acceptable gain at all three operating frequency bands. |
| Author(s): | D.-L. Jin, T.-T. Bu, J.-S. Hong, J.-F. Wang, H. Xiong |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 1129 KB |
| Title: | Full Band MIMO Monopole Antenna for LTE Systems |
| Abstract: | A novel printed planar monopole antenna for LTE multi-input and multi-output (MIMO) application is proposed. By adding six ellipticals on top of the antenna, we enhance the lower frequency bandwidth. The idea for this is gotten from [1, 2]. These papers designed by using log periodic technique with the number of rectangle and flare elements . Also, by cutting Eshaped slots in the ground plane, additional resonance is excited, and hence much wider impedance bandwidth can be produced. The proposed antenna provides all of the LTE bands between 0.65 GHz to 4 GHz. In order to provide low mutual coupling and envelope correlation, two of the antennas are combined with orthogonal polarizations. The mutual coupling and envelope correlation coefficient (ECC) of the antenna are lower than -21 dB and 0.002 across the operation bands, and total active reflection coefficient (TARC) is less than 0.35. The designed antenna has small size area of 55 × 94 mm2 , which has a small size with respect to recently reported antennas |
| Author(s): | P. Zibadoost, J. Nourinia, C. Ghobadi, S. Mohammadi, A. Mousazadeh, B. Mohammadi |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 800 KB |
| Title: | Triangular-Arranged Planar Multiple-Antenna for UWB-MIMO Applications |
| Abstract: | A triangular-arranged (TA) planar multiple-antenna is proposed. It consists of three ultra-wideband (UWB) planar monopole antenna elements, with the centers and the ports of the elements arranged at the vertexes of two regular triangles, thus the polarization of each element is 120° different. The performance of the TA multiple-antenna is investigated by simulation and measurement, and the measured results agree with the simulated ones in reasonable precision. Within the ultra-wide bandwidth of 3.4 GHz – 12 GHz, the return loss at each port is better than 10 dB, and the isolation between any two ports is higher than 20 dB. Furthermore, good omni-directional radiation pattern is obtained over the interesting frequency band. A linear-arranged (LA) threeelement multiple-antenna is compared with the proposed TA antenna. Comparison between the TA antenna and the LA antenna validates the advantages of the proposed one, which consequently is suitable for UWB-MIMO applications. |
| Author(s): | X.-S. Yang, S.-G. Qiu, J.-L. Li |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 2389 KB |
| Title: | UWB Monopole Antenna with Compact Polygon-Shaped Patch for Portable Devices |
| Abstract: | In this paper, a small ultra wideband (UWB) antenna with co-planar waveguide (CPW) feed, consisting of a polygon-shaped design on the patch and a ground plane truncated with two mirror rectangular–shaped notches is designed for ultra wideband (UWB) applications. In this proposed antenna, through increasing the number of cuts inside the initial patch, a proper control on the upper frequency of the band can be achieved. The overall dimension of the antenna is 19×19 ×1 mm3 and fed by 50 ? coplanar waveguide. The proposed antenna is developed and its VSWR is compared with the simulated result. The proposed antenna operates in the adopted bandwidth (3.1 GHz-10.6 GHz) with VSWR < 2, and covers it very well from 3 GHz to 14.9 GHz, which provides fractional bandwidths of more than 132%. The effect of the ground plane notch on the optimization of the VSWR is discussed in detail. |
| Author(s): | T. Sedghi, V. Rafii, M. Moosazadeh |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 900 KB |
| Title: | Microstrip-Fed Small Slot Antenna with Dual Band-Notched Function for UWB Wireless Communications |
| Abstract: | A simple and compact microstrip-fed ultra wideband (UWB) slot antenna with dual band-notch characteristic for UWB applications has been presented. In order to increase the impedance bandwidth of the square slot antenna, we insert a T-shaped slot in the ground plane that with this structure UWB frequency range can be achieved. Additionally, by using a pair of Lshaped slits at the square radiating stub, a dual band-notch performance has been obtained. The measured results reveal that the presented dual band-notch slot antenna offers a wide bandwidth with two notched bands, covering all the 5.2 GHz / 5.8 GHz WLAN, 3.5 GHz / 5.5 GHz WiMAX and 4 GHz C bands. The designed antenna has a small size of 20×20 mm2 . Good return loss and radiation pattern characteristics are obtained in the frequency bands of interest. |
| Author(s): | N. Ojaroudi, M. Ojaroudi, N. Ghadimi |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 902 KB |
| Title: | Compact Dual-Wideband Bandpass Filter Using a Novel Multiple-Mode Resonator |
| Abstract: | This paper presents a novel dualwideband bandpass filter (BPF) structure, which consists of a two-end shorted stepped-impedance resonator with two pairs of non-identical steppedimpedance open stubs (SIOSs) and a uniformimpedance open stub (UIOS) symmetrically loaded on its high impedance section. The designed BPF has a directly coupled configuration, which can also introduce transmission zero (TZ) for filter design. The loaded SIOSs and UIOS not only excite multiple resonant modes but also introduce multiple TZs. After carefully arranging these resonant modes and TZs, the TZs can divide multiple resonant modes into multiple useful groups, which can be utilized to exploit two wideband passbands. The TZs between two passbands can improve passband selectivity and the band-toband isolation. As an example, a dual-wideband BPF centered at 1.57 / 5.59 GHz with -3 dB fractional bandwidth of 53% by 16% is designed and fabricated. The fabricated filter has a compact size of 0.16?g × 0.106?g. The measured results also exhibit a low insertion loss, good return loss and wide stopband. |
| Author(s): | J. Xu |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 308 KB |
| Title: | A Novel Compact Low-Pass Filter using Defected Ground Structure for Sharp Transition Band |
| Abstract: | This paper presents a simple technique to design a low-pass filter using defected ground structure (DGS) having a remarkable sharp response in transition band and rejection better than -20 dB up to 20 GHz. The fabricated filter has a 3 dB cutoff frequency at 3.4 GHz and it is as small as 22 mm × 12 mm. The insertion loss in the pass-band is less than 0.6 dB from DC to 3.1 GHz. The design of the filter is simple and it gives desired frequency response. Measured results show good agreement with simulated ones. |
| Author(s): | A. Mohammadi, M. N. Azarmanesh |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 650 KB |
| Title: | A Numerical Study on the Interaction Between Different Position of Cellular Headsets and a Human Head |
| Abstract: | In this paper the interaction between a human head exposed to a bluetooth-based cellular headset in different positions is studied. The exposure to the electromagnetic fields is a concern when people use these devices. The interaction of human head and bluetooth mobile headsets has not been considered in related standards. In this research three installed positions for the headset and two scenarios for the user are defined. In the first scenario the user is in free space and in the second scenario the user is in a car. For both scenarios path loss, antenna gain, total isotropic sensitivity, and specific absorption rate values for three positions of the headset on the head are obtained. SEMCAD X software is used as an FDTD-based simulation platform for our numerical studies. The result of our study can help manufacturers to consider the compatibility of these devices with safety guidelines of electromagnetic exposure specified by relevant institutes. Designers of wireless devices can use results of this study to design new headsets that can be used in an appropriate position while the performance of the device is less affected by the human head and the environment. |
| Author(s): | R. Aminzadeh, A. Abdolali, H. Khaligh |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 563 KB |
| Title: | Ultra Low RCS Measurement Using Doppler Frequency Shift |
| Abstract: | A new clutter removal method is proposed for ultra-low RCS measurement in anechoic chamber. In the proposed method, the target is moved along the line of sight of the radar in a sinusoidal manner. This movement generates some Doppler frequency shift. At the receiver, a filter matched to this Doppler shifter signal is implemented digitally. While the matched filter removes clutter signal largely it preserves the echo from the moving target. As it is shown through analytic estimation as well as simulations, the method can attenuate the clutter and noise level far beyond previously suggested methods. It also removes some of the difficulties in higher frequencies that exist in previous methods. |
| Author(s): | E. S. Kashani, Y. Norouzi, A. Tavakoli, P. Dehkhoda |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 1618 KB |
| Title: | Evaluation of Lightning Current and Ground Reflection Factor using Measured Electromagnetic Field |
| Abstract: | In this paper, an inverse procedure algorithm is proposed to evaluate lightning return stroke current wave shapes at different heights along a lightning channel, as well as the ground reflection factor using measured electromagnetic fields at an observation point while the current model can be set for different models based on the general form of the engineering current models. In order to validate the proposed method, a set of measured electromagnetic fields are used as the input parameters for the proposed algorithm. Likewise, the evaluated channel base current is compared to the corresponding measured current and also the simulated fields at another observation point (based on the evaluated current) are compared to the corresponding measured fields and the results are discussed accordingly. The results show that the evaluated current and fields based on the proposed method are in good agreement with respect to the corresponding measured values. |
| Author(s): | M. Izadi, M. A. Ab Kadir, M. Hajikhani |
| File Type: | Journal Paper |
| Issue: | Volume: 29 Number: 1 Year: 2014 |
| Download Link: | Click here to download PDF File Size: 357 KB |