Current Issue : April - June Volume : 2012 Issue Number : 2 Articles : 9 Articles
This paper demonstrates a novel dual-band operated MIMO antenna which consisted of planar monopole (main antenna) and 3D\r\nslot element (auxiliary antenna). The main antenna is printed on a 1.6mm thick FR4 board, while the auxiliary antenna is fabricated\r\nwith gold-coated copper. A lumped impedance network is applied to enhance matching effect at port1. From simulations by\r\ncommercial software, it can be found that the proposed antenna is able to cover GSM800, GSM900 (lower band), and LTE/\r\nWiMAX/WLAN (higher band) quite well. Good agreements between simulations and measurements are obtained. Corresponding\r\nmeasured results, antenna efficiency, peak gain, and radiation patterns, are presented at the same time. By equipping a passive decoupling\r\nelement, the coupling power on the ground is radiated into free space, and great enhancement of isolation between\r\nantenna elements, especially for lower band, is achieved....
In this paper software based design and analysis has been carried out for a slotted circular patch antenna for dual band applications. A circular patch (radius 22 mm and thickness 0.5 mm) with cross slot etched at center provides dual band operation. The design is analyzed by Finite Element Method based HFSS EM Simulator Software. The designed antenna operates on ISM (Industrial, Scientific and Medical) band, UMTS (3G) and C-Band....
The electromagnetic interference between electronic systems or between their components influences the overall performance. It\r\nis important thus to model these interferences in order to optimize the position of the components of an electronic system. In\r\nthis paper, a methodology to construct the equivalent model of magnetic field sources is proposed. It is based on the multipole\r\nexpansion, and it represents the radiated emission of generic structures in a spherical reference frame. Experimental results for\r\ndifferent kinds of sources are presented illustrating our method....
The isolation enhancement between the donor antenna and the service antenna for indoor repeater systems is presented by using\r\na frequency-selective surface (FSS). A unit cell of the proposed FSS consists of a quarter-wavelength resonator, a chip resistor, an\r\nFR4 substrate, and a ground plane. Applying the unit cells of the proposed FSS embedded a chip resistor on the side walls of each\r\nreflector for indoorWCDMA repeater antennas and aligning them along with the cross-polarization of each antenna, the isolation\r\nis improved by about 13 dB at theWCDMA band....
This paper presents the isolation improvement techniques of a microstrip patch array antenna for the indoor wideband code\r\ndivision multiple access (WCDMA) repeater applications. One approach is to construct the single-feed switchable feed network\r\nstructure with an MS/NRI coupled-line coupler in order to reduce the mutual coupling level between antennas. Another approach\r\nis to insert the soft surface unit cells near the edges of the microstrip patch elements in order to reduce backward radiation\r\nwaves. In order to further improve the isolation level, the server antenna and donor antenna are installedin orthogonal direction.\r\nThe fabricated antenna exhibits a gain over 7 dBi and higher isolation level between server and donor antennas below -70 dB at\r\nWCDMA band....
In this paper complete literature review of reconfigurable antennas is presented. In recent years the study of reconfigurable antenna in communication field has made great progress. Reconfigurable antenna provides selectivity in frequency, bandwidth, polarization and gain with small dimension, light weight and low price. The demand of reconfigurable antennas has increased drastically in multi-band systems, satellite communication, and mobile communication applications. The researches on this antenna are summarized and analyzed from literature....
A method to reduce truncation errors in near-field antenna measurements is presented. The method is based on the Gerchberg-\r\nPapoulis iterative algorithm used to extrapolate band-limited functions and it is able to extend the valid region of the calculated\r\nfar-field pattern up to the whole forward hemisphere. The extension of the valid region is achieved by the iterative application of a\r\ntransformation between two different domains. After each transformation, a filtering process that is based on known information\r\nat each domain is applied. The first domain is the spectral domain in which the plane wave spectrum (PWS) is reliable only within\r\na known region. The second domain is the field distribution over the antenna under test (AUT) plane in which the desired field\r\nis assumed to be concentrated on the antenna aperture. The method can be applied to any scanning geometry, but in this paper,\r\nonly the planar, cylindrical, and partial spherical near-field measurements are considered. Several simulation and measurement\r\nexamples are presented to verify the effectiveness of the method....
An active receiving antenna with small size consisting of a monopole loaded with a transistor bipolar is presented in this paper. A\ntransistor is used in order to miniaturize the receiving active antenna size in VHF band. The vertical size of the structure is equal to\n?/175, where ? is the wavelength at the lower frequency of the bandwidth. Despite the very small size of the antenna, the frequency\nbandwidth is very wide and the gain is suitable for FM application with sensitive receivers....
Multiple-input multiple-output (MIMO) synthetic aperture radar (SAR) that employs multiple antennas to transmit orthogonal\r\nwaveforms and multiple antennas to receive radar echoes is a recently proposed remote sensing concept. It has been shown that\r\nMIMO SAR can be used to improve remote sensing system performance. Most of the MIMO SAR research so far focused on\r\nsignal/data models and corresponding signal processing algorithm. Little work related to MIMO SAR antenna analysis can be\r\nfound. One of the main advantages of MIMO SAR is that the degrees of freedom can be greatly increased by the concept of virtual\r\nantenna array. In this paper, we analyze the virtual antenna array for MIMO SAR high-resolution wide-swath remote sensing\r\napplications. The one-dimensional uniformand nonuniformlinear antenna arrays are investigated and their application potentials\r\nin high-resolution wide-swath remote sensing are introduced. The impacts of nonuniform spatial sampling in the virtual antenna\r\narray are analyzed, along with a multichannel filtering-based reconstruction algorithm. Conceptual system and discussions are\r\nprovided. It is shown that high operation flexibility and reconfigurability can be obtained by utilizing the virtual antenna arrays\r\nprovided by the MIMO SAR systems, thus enabling a satisfactory remote sensing performance....
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