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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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Journal ArticleDOI
TL;DR: In this paper, a gain-enhanced pattern reconfigurable antenna is proposed, which consists of a windmill-shaped reconfigurative feeding network, four Vivaldi-shaped slots, and four groups of reconfigured artificial structures, with a gain enhancement of 1.0-3.5 dB and an FBR improvement of 4.5-8.2 dB over a wide band of 5.35-6.45 GHz.
Abstract: This letter presents a novel gain-enhanced pattern reconfigurable antenna. The proposed antenna consists of a windmill-shaped reconfigurable feeding network, four Vivaldi-shaped slots, and four groups of reconfigurable artificial structures. By electrically controlling the p-i-n diodes integrated in the feeding network and in the artificial surface, four endfire radiation patterns with enhanced gain and front-to-back ratio (FBR) are realized. The antenna is simulated and measured. Measured results show that, with the loaded reconfigurable artificial surface, a gain enhancement of 1.0-3.5 dB and an FBR improvement of 4.5-8.2 dB over a wide band of 5.35-6.45 GHz are obtained.

50 citations

Journal ArticleDOI
TL;DR: In this paper, a 20-GHz radio frequency microelectromechanical system (RF MEMS)-based electrically switchable antenna on a quartz substrate was demonstrated with a single-pole double-throw (SPDT) switch router network on a 21 mm times 8 mm chip.
Abstract: This letter demonstrates a 20-GHz radio frequency microelectromechanical system (RF MEMS)-based electrically switchable antenna on a quartz substrate Two quasi-Yagi antenna elements are monolithically integrated with a single-pole double-throw (SPDT) MEMS switch router network on a 21 mm times 8 mm chip Electrical beam steering between two opposite directions is achieved using capacitive MEMS SPDT switches in the router Port impedance and radiation patterns are studied numerically and experimentally Measured results show that the switched beam antenna features a 27% impedance bandwidth (S11 = -10 dB), a gain of 46 dBi, and a front-to-back ratio of 14 dB at 20 GHz when the control voltage is applied to one of the switch pairs of the SPDT switch

49 citations

Proceedings ArticleDOI
11 Jul 2010
TL;DR: In this article, a frequency reconfigurable quasi-Yagi dipole antenna with varactor diodes is presented, where the effective electrical lengths of the driver and director dipoles are varied by changing the biasing voltages.
Abstract: A frequency reconfigurable quasi-Yagi dipole antenna is presented in this paper. Simulation results show that a 35% continuously tuning impedance bandwidth, from 1.85 to 2.5GHz, is obtained. Loaded with varactor diodes, the effective electrical lengths of the driver and director dipoles are varied by changing the biasing voltages. The length adjustable director allows the endfire pattern with relatively high gain being maintained over each tuning sub-band. Across the tuning bandwidth, the predicted gain variation is from 5.8dBi to 7.9dBi. The H-plane cross-polarization level is below −17dB while this value is below −32dB in the E-plane. The front-to-back ratio is better than 12dB.

47 citations

Journal ArticleDOI
TL;DR: In this paper, the reflection coefficient phase is studied for four different artificial magnetic conductors (AMCs) having canonical frequency selective surface (FSS)-type two-dimensional periodic structures to be used as back reflectors for an aperture antenna.
Abstract: The reflection coefficient phase is studied for four different artificial magnetic conductors (AMCs) having canonical frequency selective surface (FSS)-type two-dimensional periodic structures to be used as back reflectors for an aperture antenna. The bidirectional circularly polarised (CP) radiation of the octagonal-shaped aperture (OSA) antenna is made unidirectional using these AMC surfaces as ground planes. The antenna height measured from the upper surface of AMC reflector to the OSA radiator is chosen to be small to realise low-profile antenna: 0.0825λ o at the lowest analysis frequency of 4.5 GHz. Different antenna parameters like voltage standing wave ratio (VSWR) of 2, 3-dB axial ratio (AR) bandwidth, gain, and front-to-back ratio are studied and compared for these four AMCs and the conventionally used perfect electric conductor (PEC) ground plane as back reflectors. Four different aperture shapes with fixed aperture perimeter are designed to integrate with the square-loop AMC as back reflector to realise a low-profile unidirectional wideband CP aperture antenna. Hexagonal-shaped aperture antenna over the square-loop AMC shows the largest measured 3-dB AR bandwidth of 23.33% (5.65-7.05 GHz), VSWR of 2 bandwidth of 36.67% (5.16-7.36 GHz), and the gain of around 7 dBic over the band for overall antenna volume of 0.72λ o × 0.60λ o × 0.19λ o at 6.0 GHz.

47 citations

Journal ArticleDOI
TL;DR: In this paper, a novel antenna structure based on a microstrip Yagi array antenna and a soft surface (SS) ring is proposed, that enables a highly directional gain in addition to an improved front-to-back (F/B) ratio of more than 20 dB.
Abstract: In this letter, a novel antenna structure based on a microstrip Yagi array antenna and a soft surface (SS) ring is proposed, that enables a highly directional gain in addition to an improved front-to-back (F/B) ratio of more than 20 dB. The SS ring is shown to be capable of greatly improving the performance while miniaturizing the design's size by half. The implementation of the SS ring to a microstrip Yagi array antenna is demonstrated to verify its functionality in suppressing surface waves, showing that an improvement of at least 3 dB in the F/B ratio can be obtained. The design is investigated at the center frequency of 5.8 GHz; however, the structure can be easily scaled to other frequency ranges. A design analysis is performed to give insight into the operational mechanism of the SS ring and the critical dimensions that affect the SS structure surrounding the antenna array. In addition, measurements are presented to validate the results obtained via simulation. The principles established in this letter can be applied to other planar antenna designs.

45 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202116
202026
201933
201823
201721
20169