Showing papers on "Front-to-back ratio published in 2015"

Effect of Loading Split-Ring Resonators in a Microstrip Antenna Ground Plane

Abstract: This study presents a new, simple method for improving the front-to-back (F/B) ratio of a microstrip patch antenna (MSA) based on surface wave suppression. The back radiation of the MSA is significantly reduced by using the meandered ground plane edges and placing split-ring resonators (SRRs) in the middle of the meandered slots. By loading SRRs near the center of the meandered ground plane edges, some parts of the diffracted back-lobe power density can be reduced further. Compared to the F/B ratio of a conventional MSA with a full ground plane of the same size, an improved F/B ratio of 18 dB has been achieved experimentally for our proposed MSA.

Anisotropic artificial material with ENZ and high refractive index property for high gain Vivaldi antenna design

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.

Substrate integrated waveguide cavity backed slot antenna with parasitic slots for dual-frequency and broadband application

Abstract: In this paper, a novel design of substrate integrated waveguide (SIW) cavity backed slot antenna for dual frequency and broadband application is demonstrated. In the proposed design, a parasitic slot is placed along with the conventional central slot at the top metallic plate of the cavity to generate dual frequency resonances at 10.08 GHz and 11.96 GHz. The central slot is placed at the center of the cavity and it is excited by TE 120 mode of the cavity to radiate into free space. However, the placement of parasitic slot in the cavity modifies the surface current distribution at top metallic plate at higher frequency and as a result, a hybrid mode resonance is achieved. Both these resonances contribute to the dual frequency operation of the antenna with unidirectional radiation pattern, high gain, high front-to-back ratio (FTBR) at both operating frequencies. The proposed antenna achieves a bandwidth of 108 MHz (1%) and 100 MHz (0.83%), a gain of 5.5 dBi and 5.3 dBi and front to back ratio of 10 dB and 12 dB respectively at first and second resonant frequency. The slot lengths can be varied to achieve a frequency ratio of two resonant frequencies in a broad range of 1.18–1.5. The length of the slot pair can also be tuned to merge the dual resonances to achieve a broadband response. A design example of broadband antenna is also demonstrated. The proposed design shows a bandwidth of 380 MHz (3.6%), a gain of 5.2–5.8 dBi and FTBR of 15 dB throughout the operating bandwidth.

Circularly Polarized Triband Printed Quasi-Yagi Antenna for Millimeter-Wave Applications

Abstract: This paper describes the design and development of a triband with circularly polarized quasi-Yagi antenna for ka-band and short range wireless communications applications. The proposed antenna consists of an integrated balun-fed printed dipole, parasitic folded dipole and a short strip, and a modified ground plane. The antenna structure, together with the parasitic elements, is designed to achieve circular polarization and triband operating at resonant frequencies of 13.5 GHz, 30 GHz, and 60 GHz. Antenna design was first simulated using HFSS ver.14, and the obtained results were compared with experimental measurements on a prototype developed on a single printed circuit board. Achieved characteristics include −10 dB impedance bandwidth at the desired bands, circular polarization axial ratio dB, front to back ratio of 6 dB, gain value of about 4 dBi, and average radiation efficiency of 60%. The paper includes comparison between simulation and experimental results.

Front-to-back ratio improvement of printed antennas based on electrically small resonators for microwave presence detectors

Abstract: The improvement of the front-to-back ratio (FBR) in low-profile antennas to be used in presence detection devices is explored. The main idea is to use electrically small resonators as radiating elements. This minimises the electric currents in the boundary of the ground plane at the working frequency, thus reducing the backward radiation. The choice of the resonant particle and its electromagnetic properties, along with the antenna structure, are discussed. The simulated results indicate that there is good impedance matching (-18 dB) at the operating frequency (3 GHz) and an excellent FBR of 24 dB. These characteristics are validated experimentally and the FBR is compared with that of a conventional patch antenna.

Planar ESPAR antenna based on Yagi-Uda array design for space diversity applications

Abstract: A planar Electronically Steerable Parasitic Array Radiator (ESPAR) antenna is proposed based on an Yagi-Uda array design for space diversity applications. Even though an conventional ESPAR antenna has various advantages of a simple structure, small volume, and cheap fabrication cost, it requires a 3-dimentional (3-D) form-factor. The proposed one is designed with planar active dipoles and parasitic element arrays from an Yagi-Uda design methodology. Four orthogonal arrays are configured of two active elements and eight parasitic elements, which is implemented with two bi-directional arrays. Each array has an active element, two reflector elements, and two director elements. The proposed architecture has been implemented on a planar substrate, and controlled with switched reactance for each parasitic element. From the experimental results, the proposed planar ESPAR antenna presents four orthogonal beams with a maximum gain of 10.74 dBi and a front to back ratio of 14.7 dB.

Wideband Circular Polarization Cavitay-Backed Slot Antenna for GNSS Applications

Abstract: This paper presents a wideband circular polarization antenna for Global Navigation Satellite System (GNSS). By exciting four slots etched along each edge of a square ground with equal amplitude and 90 ◦ phase difference, good circular polarization performance is achieved. A novel radiation element, composed of back-side slot and front-side monopole, is proposed to realize a wideband radiation. Meanwhile, the feed network composed of Schiffman phase shifters and Wilkinson power dividers maintains this wideband performance. A backed cavity is used to suppress the backward radiation, therefore enhances the frontward gain. Measured results of the fabricated antenna show good agreement with the simulated ones. The main advantages of this antenna include its wide bandwidth, good circular polarization, high front to back ratio, low cost, and easy fabrication, which make it very attractive for GNSS terrestrial applications.

A circularly polarized antenna based on EMSIW sub-array with high front-to-back ratio

Abstract: A high front-to-back ratio circularly polarized planar antenna is presented in this communication based on a quarter-mode substrate integrated waveguide sub-array. It is composed of three parts: an eighth-mode substrate integrated waveguide (EMSIW) sub-array, four coaxial cables which are used to connect the probe-fed sub-array and the corporate feed network, and the feed network of which composed three Wilkinson power dividers is applied to feed the array. The measured front to back radiation ratio and the measured antenna gain for right-hand circular polarization (RHCP) are 28.6 dB and 6.61 dBi at 5.2 GHz, respectively. The measured 10-dB return loss and 3-dB axial ratio bandwidths at the center frequency 5.2 GHz are 21.53% and 10.96%, respectively.

Self‐phasing of quadrifilar helix antenna by relative axial displacement of bifilars

Abstract: Self-phasing can be achieved in a quadrifilar helix antenna (QHA) by displacing one of the bifilars along the axis of the helix, yielding a circularly polarized cardioid shaped pattern. Impedance bandwidth of 10% (2105-2345 MHz) has been achieved with Front to back ratio greater than 10 dB.

Wide Bandwidth Endfire Antenna with Log-Period Directors

Abstract: This paper presents the design and implementation of a novel wide bandwidth endfire antenna with log-periodic directors. The feeding structure of the proposed antenna includes a balun which is formed using a pair of microstrip-to-slotline transitions. The proposed antenna has three resonant frequencies in the operating frequency band. Both simulation and measurement results show that the operating frequency band of the antenna for S11 18 dB and cross polarization level below -28 dB. The dimension of the proposed antenna is 26 mm × 27 mm. Good return loss and radiation pattern characteristics are obtained and measured results are presented to validate the usefulness of the proposed antenna structure for wide bandwidth endfire applications.

Double side high frequency flat plate antenna

Abstract: The utility model relates to an antenna, and especially relates to a high frequency flat plate antenna with the band of 2500MHZ to 2700MHZ The existing high frequency flat plate antenna cannot meet the existing demand due to low national standard of front to back ratio The double side high frequency flat plate antenna provided by the utility model comprises an antenna base plate (1) and sides (2) The sides (2) are located on both sides of the antenna base plate (1), and are fixedly connected with the antenna base plate (1) The double side high frequency flat plate antenna is characterized in that two sides (2) are arranged on each side of the antenna base plate (1); the heights of two sides (2) are different; the heights of two sides (2) on each side of the antenna base plate (1) are different; and the height of the outer side (3) is higher than the height of the inner side (4) According to the high frequency flat plate antenna structure provided by the utility model, the front to back ratio exceeds the national standard; the structure is simple; simple improvement is carried out based on the existing structure; and the effect is obvious

Low frequency flat plate antenna with high front to back ratio

Abstract: The utility model relates to an antenna, and especially relates to a low frequency flat plate antenna with the band of 824MHZ to 960MHZ. The existing low frequency flat plate antenna cannot meet the existing demand due to low national standard of front to back ratio. The low frequency flat plate antenna with high front to back ratio, which is provided by the utility model, comprises an antenna base plate (1) and sides (2). The sides (2) are located on both sides of the antenna base plate (1), and are fixedly connected with the antenna base plate (1). Two sides (2) are arranged on each side of the antenna base plate (1). In both sides of the antenna base plate (1), one end, which does not contact the antenna base plate (1), of at least one side of each side is wavy. The low frequency flat plate antenna provided by the utility model has the advantages of simple structure and easy processing. The best front to back ratio of the antenna is up to 30db, is much higher than the national standard, and basically meets the existing demand.

Double side intermediate frequency flat panel antenna

Abstract: The utility model relates to an antenna, and especially relates to an intermediate frequency flat plate antenna with the band of 1710MHZ to 2500MHZ The existing intermediate frequency flat plate antenna cannot meet the existing demand due to low national standard of front to back ratio The double side intermediate frequency flat plate antenna provided by the utility model comprises an antenna base plate (1) and sides (2) The sides (2) are located on both sides of the antenna base plate (1), and are fixedly connected with the antenna base plate (1) The double side intermediate frequency flat plate antenna is characterized in that two sides (2) are arranged on each side of the antenna base plate (1); the heights of two sides (2) are different; the heights of two sides (2) on each side of the antenna base plate (1) are different; and the height of the outer side (3) is higher than the height of the inner side (4) According to the intermediate frequency flat plate antenna structure provided by the utility model, the front to back ratio exceeds the national standard; the structure is simple; simple improvement is carried out based on the existing structure; and the effect is obvious

Performance Analysis of Microstrip Antenna Using GNU Radio with USRP N210

Abstract: Radiation pattern and power spectrum measurements become inevitable while analysing performance of an antenna. Current test bench for these measurements are considerably costly. In this paper, the performance of microstrip antenna is evaluated using GNU (GNU is Not Unix) Radio companion (GRC) and Universal Software Radio Peripheral (USRP). The radiation pattern obtained is used in the measurement of Half Power Beam Width and Front to Back Ratio of the antenna. In addition to these measurements, received signal power is also calculated using the Frobenius norm method. Finally, the economic advantage of the proposed method is compared with conventional measurements.

An extraordinary transmission analogue for enhancing microwave antenna performance

Abstract: The theory of diffraction limit proposed by H.A Bethe limits the total power transfer through a subwavelength hole. Researchers all over the world have gone through different techniques for boosting the transmission through subwavelength holes resulting in the Extraordinary Transmission (EOT) behavior. We examine computationally and experimentally the concept of EOT nature in the microwave range for enhancing radiation performance of a stacked dipole antenna working in the S band. It is shown that the front to back ratio of the antenna is considerably enhanced without affecting the impedance matching performance of the design. The computational analysis based on Finite Difference Time Domain (FDTD) method reveals that the excitation of Fabry-Perot resonant modes on the slots is responsible for performance enhancement.

Broadband directional antenna on an EBG structure for body-centric wireless communication

Abstract: A thin broadband textile dipole antenna on an EBG structure is proposed for body-centric wireless communications. The proposed antenna (44 × 44 × 2.5 mm3) leverages a Non-Uniform Aperiodic (NUA) EBG surface as its reflector and reduces the overall thickness to 2.5 mm for operation between 6–9.75 GHz. The proposed antenna has 48% bandwidth, 4–8 dBi of gain and high Front to Back ratio (F/B).

Meshed Patch Antenna for Portable UHF Band Radio Communication Devices

Abstract: This paper presents a meshed microstrip patch antenna for UHF band radio communications. Meshed elements allow making antenna flexible, light and more suitable for wearable devices. Several antennas, intended for PMR446 band with different meshing configurations, have been designed. Un-meshed, semi-meshed and fully meshed microstrip patch antennas have been compared. The analysis was focused on the best tradeoffs between concentration of conductor, gain and front to back ratio. Results below are showing that more than 50 % of conductor can be removed without significant gain reduction. In some cases the meshing gives a reduction of back radiation. The meshed antenna has smaller dimensions in comparison with the unmeshed antenna on the same frequency. DOI: http://dx.doi.org/10.5755/j01.eee.21.4.12778

Meshed Patch Antenna for Portable UHF Band Radio Communication Devices

Abstract: This paper presents a meshed microstrip patch antenna for UHF band radio communications. Meshed elements allow making antenna flexible, light and more suitable for wearable devices. Several antennas, intended for PMR446 band with different meshing configurations, have been designed. Un-meshed, semi-meshed and fully meshed microstrip patch antennas have been compared. The analysis was focused on the best tradeoffs between concentration of conductor, gain and front to back ratio. Results below are showing that more than 50 % of conductor can be removed without significant gain reduction. In some cases the meshing gives a reduction of back radiation. The meshed antenna has smaller dimensions in comparison with the unmeshed antenna on the same frequency. DOI: http://dx.doi.org/10.5755/j01.eee.21.4.12778