Current Issue : July - September Volume : 2015 Issue Number : 3 Articles : 10 Articles
A new compact design of monopole antenna for triple-band WLAN/WiMAX applications with two band-notches based on\nbroadband antenna is presented. By introducing a stub loaded ground and two new paper clip structures etched on radiation patch,\na compact overall dimension 31mm Ã?â?? 33mm Ã?â?? 1mm and three separated operating bands effectively covering 2.4/5.2/5.8GHz\nWLAN bands and 2.5/3.5/5.5GHz WiMAX bands can be achieved. Compared with familiar U type slot, the introduced compact\npaper clip structure can save about 37% of dimension regions, which could effectively improve efficiency of band-notch formation.\nSimulated and measured results demonstrate that the proposed antenna has good dipole-like radiation characteristics with\nappreciable gain across the operating bands. Besides, main parameters of the two etched paper clip structures are investigated\nto control the positions and bandwidths of the two stop-bands, respectively, on basis of which the three working bands can be\nadjusted independently....
An optimal resource allocation strategy for MIMO relay system is considered in simultaneous wireless information and energy\ntransfer network, where two users with multiple antennas communicate with each other assisted by an energy harvesting MIMO\nrelay that gathers energy from the received signal by applying time switching scheme and forwards the received signal by using the\nharvesting energy. It is focused on the precoder design and resource allocation strategies for the system to allocate the resources\namong the nodes in decode-and-forward (DF) mode. Specifically, optimal precoder design and energy transfer strategy in MIMO\nrelay channel are firstly proposed. Then, we formulate the resource allocation optimization problem. The closed-form solutions for\nthe time and power allocation are derived. It is revealed that the solution can flexibly allocate the resource for the MIMO relay\nchannel to maximize the sum rate of the system. Simulation results demonstrated that the performance of the proposed algorithm\noutperforms the traditional fixed method....
A convectional microstrip Antenna having radiating patch on dielectric substrate supported by ground plane having an attractive features and planar structure which is inherently used in practical application. Paper represents design of circular patch antenna fed via 90° hybrid coupler in order to obtain circular polarization. A two port circular microstrip patch antenna was investigated in this paper. The antenna was designed for operating in S band (2 – 4 GHz, with centre frequency 2.12 GHz) frequency range with a circular polarization. The paper also presents the detail steps of designing the circular patch microstrip antenna and the simulated result, ANSOFT HFSS software was used to compute the S11, gain, current distribution and axial ratio of the antenna, which has application in monopulse radar and satellite communication....
In recent years development of wearable antennas for wireless communication system is a very important field of knowledge. Wearable antenna serves as element of clothes, whose purpose is performing tasks related to telecommunications such as tracking and navigation, remote computing and communication tasks related to public safety. The paper present the design of the wearable antenna made in micro strip technique working at a frequency of 5.5 GHz. Here Jeans textile is used as substrate for this antenna.The antenna is fed with inset feed.Here,examined the radiation characteristic, return loss and gain which are the critical parameters of wearable antenna....
For most joint direction of arrival (DOA) and polarization estimation methods, the performances of proposed methods in dealing\nwith unequal power sources are not discussed.However, sources with unequal powers apparently exist widely in actual applications.\nIn this study, we propose a joint DOA and polarization estimation method for unequal power sources by utilizing the invariance\nproperty of noise subspace (IPNS) to the power of sources. This work extends the IPNS method to the dual polarized antenna array\nfor joint DOA and polarization estimation. Moreover, we theoretically prove that the IPNS remains valid even when the sources\nare correlated. The computer simulations illustrate that the proposed method can effectively estimate the DOA and polarization\nparameters as the power difference between sources increases, as opposed to the polarimetric multiple signal classification (MUSIC)\nalgorithm, which suffers from degradation in resolution probability. In addition, the performances of the proposed method are\nprovided, as well the Cramer Rao Bound (CRB), which show approximate performance as the polarimetric MUSIC algorithm....
The multiple-input-multiple-output (MIMO) synthetic aperture radar (SAR) system with a linear antenna array can obtain 3D\nresolution. In practice, it suffers from both the translational motion errors and the rotational motion errors. Conventional single channel\nmotion compensation methods could be used to compensate the motion errors channel by channel. However, this method\nmight not be accurate enough for all the channels.What is more, the single-channel compensation may break the coherence among\nchannels, which would cause defocusing and false targets. In this paper, both the translational motion errors and the rotational\nmotion errors are discussed, and a joint multichannel motion compensation method is proposed for MIMO SAR 3D imaging. It is\ndemonstrated through simulations that the proposed method exceeds the conventional methods in accuracy. And the final MIMO\nSAR 3D imaging simulation confirms the validity of the proposed algorithm....
A low-profile monopole antenna with height below ?0/16 is proposed. The antenna is based on a square substrate-integrated\ncavity radiating through apertures in its four side walls. This effectively creates a small square loop of magnetic currents, which\nradiates omnidirectionally as an electric monopole.The antenna cavity has a side length of less than ????0/3 and thus resonates in the\nmonomode region, in a fundamental TM11 mode. This means that the structure is robust in terms of feeding and manufacturing\ntolerances, as no parasitic modes can be excited. The designs of the cavity and the feed are introduced in detail. The measurement\nresults from a manufactured prototype operating at 5.9GHz show good agreement with simulations and validate the proposed\napproach....
Genetic algorithm (GA) has been a popular optimization technique used for performance improvement of microstrip patch\nantennas (MPAs).When using GA, the patch geometry is optimized by dividing the patch area into small rectangular cells. This has\nan inherent problem of adjacent cells being connected to each other with infinitesimal connections, which may not be achievable\nin practice due to fabrication tolerances in chemical etching. As a solution, this paper presents a novel method of dividing the patch\narea into cells with nonuniform overlaps. The optimized design, which is obtained by using fixed overlap sizes, shows a quad-band\nperformance covering GSM1800, GSM1900, LTE2300, and Bluetooth bands. In contrast, use of nonuniform overlap sizes leads to\nobtaining a pentaband design covering GSM1800, GSM1900, UMTS, LTE2300, and Bluetooth bandswith fractional bands with of\n38% due to the extra design flexibility....
A novel robust adaptive beamforming based on worst-case and norm constraint (RAB-WC-NC) is presented. The proposed\nbeamforming possesses superior robustness against array steering vector (ASV) error with finite snapshots by using the norm\nconstraint and worst-case performance optimization (WCPO) techniques. Simulation results demonstrate the validity and\nsuperiority of the proposed algorithm....
Target localization in urban sensing can benefit from angle dependency of the pulse shape at a radar receiver antenna.We propose\na localization approach that utilizes the embedded directivity in ultra-wideband (UWB) antennas to estimate target positions. A\nsingle radar unit sensing operation of indoor targets surrounded by interior walls is considered, where interior wall multipaths are\nexploited to provide target cross-range. This exploitation assumes resolvability of the multipath components,which is made possible\nby the virtue of using UWB radar signals.The proposed approach is most attractive when only few multipaths are detectable due\nto propagation obstructions or owing to low signal-to-noise ratios. Both simulated and experimental data are used to demonstrate\nthe effectiveness of the proposed approach....
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