Showing papers on "Front-to-back ratio published in 2000"
TL;DR: In this paper, a coplanar waveguide fed quasi-Yagi antenna is used to achieve a wide bandwidth and cross-polarization better than -17 dB at 10 GHz.
Abstract: A novel coplanar waveguide fed quasi-Yagi antenna is presented. A wide bandwidth is achieved by using a broadband coplanar waveguide to a slotline balun. An X-band prototype has been realised which demonstrates a broad bandwidth (30%), –19 dB front-to-back ratio, and cross-polarisation better than -17 dB at 10 GHz.
111 citations
03 Dec 2000
TL;DR: In this paper, the authors designed an antenna array consisting of a center driven element circled by four parasitic elements symmetrically arranged, which achieved a front to back ratio of approximately 15 dB, S/sub 11/ less than -35 dB and 360 degree coverage of within 1.5 dB of the main lobe gain for both frequencies.
Abstract: Wire dipole and monopole switched-parasitic antennas have been designed to operate at 900 and 1900 MHz simultaneously. The array consists of a centre driven element circled by four parasitic elements symmetrically arranged. DC levels applied to p.i.n. diodes on each parasitic element allow full 360 degree coverage in the horizontal plane. The design of the antenna was undertaken using the genetic algorithm technique with the NEC2 solver. The design was optimised for element spacing and lumped impedance size and position. The cost function included the input impedance and directional characteristics at both frequencies. The final design has a front to back ratio of approximately 15 dB, S/sub 11/ less than -35 dB and 360 degree coverage of within 1.5 dB of the main lobe gain for both frequencies.
79 citations
Patent•
28 Feb 2000
TL;DR: An antenna structure including a ground plane (12) that provides a good front to back ratio while maintaining a small size and which can mechanically be made to fit into tight areas is described in this article.
Abstract: An antenna structure including a ground plane (12) that provides a good front to back ratio while maintaining a small size and which can mechanically be made to fit into tight areas. The antenna structure may be a GPS patch antenna (10), or any other antenna adapted to receive broadcast signals. The ground plane (12) is made from radar absorbing material (14, RAM) in electrical contact with conductive radials (16). The RAM (14) inherently acts to suppress surface currents on the ground plane (12), which in turn reduces back signals. Although RAM (14) has some resistance, it is low enough such that the electrical effect of the radials (16) is extended through the RAM (14), essentially simulating a 'solid' conductive disk. Both the RAM (14) and radials (16) may be made from light and flexible material, and consequently may be adapted for use in a variety of applications.
24 citations
TL;DR: In this paper, a broadband microstrip patch antenna well suited for monolithic microwave integrated circuits (MMICs) is presented, which exhibits a measured bandwidth of 35%, low surface wave loss, a high front-to-back ratio, and is fabricated directly on the MMIC substrate material.
Abstract: A broadband microstrip patch antenna well suited for monolithic microwave integrated circuits (MMICs) is presented. The antenna exhibits a measured bandwidth of 35%, low surface wave loss, a high front-to-back ratio, and is fabricated directly on the MMIC substrate material. The predicted and measured input impedances are given along with the measured radiation performance.
24 citations
10 Sep 2000
TL;DR: In this paper, the design of a X-band single radiator for a wide-band dual polarized-aperture coupled stacked patch microstrip antenna is introduced, and a bandwidth of 2 GHz with enhanced port decoupling, improved front to back ratio and high gain can be obtained by using thin substrates for the feeding network.
Abstract: The design of a X-band single radiator for a wide-band dual polarized-aperture coupled stacked patch microstrip antenna is introduced. A bandwidth of 2 GHz with enhanced port decoupling, improved front to back ratio and high gain can be obtained by using thin substrates for the feeding network. Simulated and measured results of S-parameters and measured radiation patterns are presented.
9 citations
TL;DR: In this article, an exhaustive parametric study of 3-element and 6-element Yagi-Uda antennas has been carried out using Method of Moments (MOM) for TV reception and other applications in the VHF/UHF band.
Abstract: Yagi-Uda antenna is extensively used for TV reception and other applications in the VHF/UHF band. Because of mutual interaction among the array elements, the directivity (D), front to back ratio (F/B), and Input impedance (Zin) are complicated functions of element dimensions and their relative spacings. Hence, an exhaustive parametric study of 3-element and 6-element Yagi-Uda antennas has been carried out using Method of Moments (MOM). The performance of both 3-element and the 6-element Yagi-Uda antennas has been optimized with respect to D, F/B, and VSWR.
3 citations
06 Jul 2000
TL;DR: In this paper, the performance of slot antennas and shielded dipole antennas, including resistive material or resistive elements, is investigated. But, the authors did not consider the influence of the spacing between the antennas and the ground.
Abstract: Slot antennas and shielded dipole antennas, including resistive material or resistive elements, are considered. Numerical modeling has been carried out by finite difference method in time domain and by integral equation method in frequency domain. The following characteristics has been studied: `front to back' ratio, near field patterns for pulse radiation, far field patterns and energy flux distribution in frequency domain, gain to the ground and the air, input impedance, transient response. An influence of the spacing between the antennas and the ground was studied. Several ways of using of resistive elements and covering were considered: placing of the resistive material into the spacing and around slot antennas, between the dipole and it's screen, including of resistive elements to the bottom surface of the slot antenna, resistive screen of slot antennas. Some optimal antennas have been found. Influence of antenna's design to characteristics is shown. Dipole antenna with a resistive material between the dipole and the screen may provide greater front to back ratio, then the slot antennas, having the same size. Slot antenna with resistive covering on lateral sides ensures high front to back ratio when it is placed on the ground. Optimal conductivity of resistive covering around slot antennas have been found depending of type of the covering and conductivity of the ground.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
2 citations
27 Apr 2000
TL;DR: In this article, the effect of the spacing between the antennas and the ground surface for soils having various dielectric constant and conductivity was studied, and the optimal conductivity of the resistive covering have been found for various types of the covering of the slot antennas.
Abstract: Slot antennas, with and without resistive covering, dipole antennas having a screen have been modeled by finite difference scheme in time domain. The following characteristics has been studied: 'front to back' ratio, field patterns for pulse radiation, coupling between transmitting and receiving antennas. An influence of the spacing between the antennas and the ground surface for soils having various dielectric constant and conductivity was studied. Optimal conductivity of the resistive covering have been found for various types of the covering of the slot antennas. Filling of the spacing between the antenna and the ground by the resistive material leads to large increase of the front to back ratio, the optimal conductivity depends on the spacing. When the antenna is covered on lateral sides, the optimal conductivity is greater. Partial filling of the spacing leads to moderate increase of the front to back ratio. Dipole antenna with a screen and resistive material between the dipole and the screen, placed at some height above the ground, provides greater front to back ratio, than the slot antenna, having the same size. Computed field patterns and other characteristics enable to understand behavior of the radiation of the antennas and are useful in designing of shielded antennas.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
2 citations