Serwis Infona wykorzystuje pliki cookies (ciasteczka). Są to wartości tekstowe, zapamiętywane przez przeglądarkę na urządzeniu użytkownika. Nasz serwis ma dostęp do tych wartości oraz wykorzystuje je do zapamiętania danych dotyczących użytkownika, takich jak np. ustawienia (typu widok ekranu, wybór języka interfejsu), zapamiętanie zalogowania. Korzystanie z serwisu Infona oznacza zgodę na zapis informacji i ich wykorzystanie dla celów korzytania z serwisu. Więcej informacji można znaleźć w Polityce prywatności oraz Regulaminie serwisu. Zamknięcie tego okienka potwierdza zapoznanie się z informacją o plikach cookies, akceptację polityki prywatności i regulaminu oraz sposobu wykorzystywania plików cookies w serwisie. Możesz zmienić ustawienia obsługi cookies w swojej przeglądarce.
Synthetic time domain processing can be used to produce range-only RCS images of stationary targets in the laboratory environment. If the target is rotated in angle, two dimensional images can also be constructed. However, to image a moving target, the synthetic time-domain processing must use pulsed signals. The DREO I/J band RCS measurement radar has recently been modified so it can collect coherent...
A line of base station antenna products using microstrip technology has been developed for use in cellular communications. The antennas operate In the 800–900 MHz range. The main product is a half cylinder three beam radome enclosed antenna. There are three microstrip planar array panels within the half cylindrical radome. Each microstrip planar array panel illuminates one 60∗ sector and all three...
Vichniac has stated that “Exact numerical reversibility yields instability in the presence of an attractor” [1]. Vichniac's statement relates the reversibility of an algorithm (i.e., its ability to preserve the information encoded in its initial conditions) to the dynamics of an attractor. In this paper, the relevance of Vichniac's statement to the time-domain numerical methods applied to model electromagnetic...
The conventional design approach to provide a shaped beam antenna pattern has been to illuminate a paraboloid reflector with a multielement feed array. The beam shaping is achieved by selection of the size and placement of the feed elements in the focal plane of the reflector, and the excitation coefficient which drive the elements. Recent developments at Space Systems/Loral have proven the benefits...
Intensive investigations of the millimeter waves spectrum are stimulated by the requirements of large bandwidth adapted to the high bit rate of the future wireless LAN. This paper deals with experimental results obtained for the narrowband and wideband indoor radio channels at 37.2 GHz. CW results are obtained using two kinds of transmission antennas, omnidirectional and directional Under LOS condition,...
In this paper, the analysis of slot-coupled microstrip structures is considered. Typical methods applied to the analysis of this class of problem include: analytic techniques such as modal-field analysis [1], cavity models [2]; and the numerical solution of integral-equation formulations [3]. The Transmission Line Matrix (TLM) method is a general numerical technique for obtaining an approximate solution...
The RADARSAT mission utilizes a Synthetic Aperture Radar (SAR) system to produce images representing terrain radiometric backscatter levels. The SAR system consists of Space and Ground Segments. The Space Segment is a polar orbiting satellite at 800 km nominal altitude carrying a C-band (5.3 GHz) radar sensor. The Ground Segment provides the SAR image data processing facility, as well as the associated...
Because of low profile planar configuration, light weight, and ease of fabrication microstrip antennas are attractive candidates for personal communication applications. In array forms, they can be used to provide high gains to replace conventional antennas, such as the paraboloid and dual reflector antennas. However, at high EHF frequencies the resistive losses associated with their feed network...
This paper describes the design and development of a low profile phased array suitable for INMARSAT Standard-M vehicular satellite communications. The array consists of twelve dual layer elements symmetrically positioned on a circular disk. The lower microstrip patches are fed directly to radiate right-handed circular polarization while the upper patches act as parasitic elements. Optimization has...
In recent years, the investigation of inverse scattering problems in the area of microwave imaging has been performed mainly by applying iterative algorithms. The method based on me Born approximation [1] and the method using a Newton-type iterative algorithm [2] are two typical iterative methods currently being employed. An improved technique based on the equivalent current reconstruction has been...
The second flight unit of the Italian telecommunication satellite (ITALSAT F2) will embark an L-band multicarrier payload for European Mobile Service (EMS) replacing the 40/50 GHz experimental propagation package presently in orbit with ITALSAT F1. The EMS payload has introduced the passive intermodulation (PIM) products problem into the Italsat spacecraft previously not designed to be PIM free. This...
The RADARSAT Synthetic Aperture Radar (SAR) antenna is a large (1.5m × 15m) slotted waveguide planar array operating at 5.3 GHz. The antenna comprises 32 slotted waveguide rows, and is mechanically divided into 4 panels to enable stowage during launch. Each waveguide row is fed by a 1-to-8 azimuth power dividing network (APDN). The 32 rows of the APDN are excited across the 1.5m dimension by the elevation...
The amplifier-types of active antennas, in which amplifiers are integrated with microstrip patches, is an innovative topic recently [1], [2]. In addition to the advantages of reducing the losses in the feed circuits, this type of active antennas can be designed with both higher realized gain and wider gain bandwidth than their passive counterparts when active concept is employed [3]. This type of...
The synthetic aperture radar (SAR) antenna on-board the Canadian remote sensing satellite, RADARSAT, is a large deployable planar array (1.5m × 15m) [1], [2]. It provides a set of selectable pseudo-trapezoidal elevation beam shapes (see figure 1–1) which afford flexible coverage within a 500 km wide accessibility region, which runs parallel to, and to the side of, the orbital plane of the spacecraft...
A new Full Wave Finite Difference (FWFD) is proposed which is capable of evaluating field patterns of guided wave structures simultaneously and efficiently. Unlike the traditional finite difefrence methods, its formulation is based on all six vector field components.
A dispersion model for shielded microstrip lines is given here for the first time. This model is valid for a wide range of values of frequency, geometrical parameters and of relative dielectric constants. Unlike previous models for open microstrip lines, the inflection frequency of the dispersion curve has been shown to be a polynomial of the frequency at which the quasi TEM mode of the microstrip...
The CAL AMT-100 system provides communications capabilities for an aircraft. Via the Inmarsat series of L-band satellites, voice or data facilities (phone, fax etc.) are available globally on demand. The antenna for the system (Fig. 1) is housed in a tail-mounted radome, and is mechanically scanned in two dimensions to track the satellite.
The analysis presented in this paper provides a polarimetric observation over the Kelvin's wake sensed by a SAR in a numerical simulation. A computer simulation of L band SAR images of surface ship wakes is described and the results analysed. The model accounts for the perturbation in the fluid by the ship and the influence of the sea in calm wind conditions. The fluctuations of the Kelvin's waves...
An active integrated antenna may be defined as a radiating element on which the current distribution along the structure may be altered in a controlled manner. The ability to control the current distribution along its structure is the unique feature of this class of antennas and gives it its primary advantage. With this ability, radiation characteristics such as pattern shape, axial ratio, and gain...
Most phenomena is interpreted by its special differential equations and relating boundary values. Mathematically in order to interpret the phenomena, we consider the wave function(ψ), Wave functions derived from the original differential equation of the phenomena. General space part spherical wave function is:, (▿2+k2)ψ=0, where ψ= ψ(r,θ,ϕ) in spherical. The equation can describe diverse phenomena...
Podaj zakres dat dla filtrowania wyświetlonych wyników. Możesz podać datę początkową, końcową lub obie daty. Daty możesz wpisać ręcznie lub wybrać za pomocą kalendarza.