Topic
Front-to-back ratio
About: Front-to-back ratio is a research topic. Over the lifetime, 292 publications have been published within this topic receiving 3314 citations.
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08 May 2010
TL;DR: In this article, a novel wide beam UWB antennae design for Impulse Radio-Ultra Wide Band (IR-UWB) Through-the-Wall detection radar is presented.
Abstract: This paper presents a novel wide beam UWB antennae design for Impulse Radio-Ultra Wide Band (IR-UWB) Through-the-Wall detection radar. The design is based on a typical bowtie slot antenna structure with an added reflector in order to achieve unidirectionality and wide beam. The effects of different parameters of the added reflector on the impedance and radiation characteristics are analyzed. The different structural parameters of antenna are optimized by numerical simulations. Simulated and measured results show that the front-to-back ratio is great than 10dB and the beam width is approximately 120° ~145 ° within operation band for |S11|<-10dB (0.8GHz~2.3GHz).
12 citations
TL;DR: In this article, a new low cost switched-beam antenna array suitable for 2.4 GHz ISM applications is presented, which consists of four planar inverted-F antennas sharing the same ground plane, in a configuration designed for symmetrical coverage of the horizontal plane.
Abstract: A new low cost switched-beam antenna array suitable for 2.4 GHz ISM applications is presented in this paper. The proposed structure consists of four planar inverted-F antennas (PIFA), sharing the same ground plane, in a configuration designed for symmetrical coverage of the horizontal plane (Quad-PIFA). A custom Genetic Algorithm (GA) is used in order to optimize the array parameters regarding resonation frequency and radiation pattern orientation angle and beamwidth. The optimized Quad-PIFA exhibits low profile (size equal to 8 cm × 8 cm), high front to back ratio (15.6 dB), and satisfactory directivity (3.6 dB) over an operational bandwidth of over 200 MHz. Simulation and measurement results are presented indicating consistency between design and implementation and demonstrating the performance of the array.
12 citations
26 Apr 2011
TL;DR: In this article, an octafilar helical antenna (OFHA) is proposed for handheld ultra-high-frequency (UHF) radio frequency identification (RFID) reader, which is designed at UHF band centred at 915 MHz.
Abstract: Octafilar helical antenna (OFHA) is proposed for handheld ultra-high-frequency (UHF) radio frequency identification (RFID) reader. The investigated antenna configuration consists of OFHA placed on reader device in the presence of human hand model. The antenna is designed at UHF band centred at 915 MHz. The antenna return loss, axial ratio, gain, co-polarized and cross-polarized field components are calculated using the finite element method (FEM) and compared with that calculated by finite integration technique (FIT) for verification of the simulated results. A comparison between the performance of the quadrifilar helical antenna (QFHA) and the octafiliar helical antenna (OFHA) designed at 915 MHz in the presence of the reader device and human hand model is investigated. The OFHA introduces high gain, high front to back ratio, good axial ratio and omnidirectional coverage.
12 citations
TL;DR: A wideband beam-switching metasurface antenna using programmable unit-cells is proposed for electromagnetic torso scanning and is successfully tested on altering the intensity of the electric field at right, center and left sides of a torso phantom.
Abstract: A wideband beam-switching metasurface antenna using programmable unit-cells is proposed for electromagnetic torso scanning. The design aims at changing the intensity of the electric field inside the torso without any mechanical movements and thus enables fast electronic scanning of the torso. The antenna consists of an H-shape microstrip-fed slot as the radiator and a metasurface layer containing 5 × 5 programmable square ring resonator as the superstrate layer. Four PIN diodes are embedded in each cell to alter the electric field intensity within the metasurface layer and consequently switch the radiation pattern in the azimuth plane, elevation plane, and diagonal axis of the metasurface layer. As a proof of concept, a prototype antenna capable of switching the radiation pattern from -25° to +25° in the azimuth (x-z) plane is fabricated and measured. The antenna, which has the compact size of 0.9λ
0
×0.9λ
0
×0.06λ
0
(where λ
0
is the wavelength at the center operation frequency), achieves a wide bandwidth of 30% at 0.9-1.2 GHz. The peak measured gain is 9.5 dBi with maximum front to back ratio of 12 dB. The fabricated antenna is successfully tested on altering the intensity of the electric field at right, center and left sides of a torso phantom.
12 citations
01 Nov 2015
TL;DR: In this paper, an anisotropic artificial material (AAM) is proposed which shows epsilon near zero (ENZ) or zero index metamaterial (ZIM) property and effective refractive index greater than 1, simultaneously in a direction.
Abstract: In this paper, an anisotropic artificial material (AAM) is proposed which shows epsilon near zero (ENZ) or zero index metamaterial (ZIM) property and effective refractive index greater than 1, simultaneously in a direction. Further, the proposed material is investigated to improve the gain of an ultrawideband (UWB) Vivaldi antenna (VA). The unit cell of AAM consists of compact meandered line metallic strip on a dielectric substrate. The AM shows the ENZ property in the frequency band of 8 GHz–12 GHz due to the electrical resonance along the meandered axis of the AAM. While, due to the non-resonant electrical property in the direction orthogonal to the meandered axis high refractive index property is observed in UWB. Significant gain enhancement of up to 2 dBi is observed due to the AAM. The VA with AAM shows good unidirectional radiation characteristics with improved front to back ratio in the UWB.
12 citations