The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The feasibility of using the spherical wave method (SWM) to analysis the shaped beam, singly curved reflector antennas is investigated in this paper. It is shown that for low sidelobe level (SLL) beams, or main beam scanned, the reflector length is longer than the line source length, but the cylindrical wave method (CWM) couldn't deal with this additional part. Calculated results by the SWM and the...
The performance of adaptive beamforming degrades in presence of signal model mismatches. In particular, when the desired signal is present in training snapshots, the adaptive beamforming is quite sensitive to desired signal steering vector mismatch. Therefore, a robust adaptive beamforming for actual system is proposed based on the reconstruction of interference covariance matrix and mismatched steering...
In ideal cases, assumptions are made that the direction of the desired signal is accurately known and there are no array position errors. But in practice, some errors of DOA estimation and array geometries will bring the uncertainty of steering vector of the desired signal. Then, investigation is needed to solve the beamforming problem when steering vector error is uncertain. In this paper, we propose...
In order to solve the problem that most of the directions-of-arrival (DOA) algorithms are based on the prior knowledge of source number and the estimation error of source number leads to the degradation of DOA algorithm performance, a conformal array DOA algorithm with unknown source number is proposed. This method is realized by introducing the pseudo expected signal. The optimum weight deduced by...
Gradient metasurfaces (GMs) can provide additional parallel wave vectors for reflected waves and thus anomalous reflection can be induced. Hence, EM wave reflection can be redirected using reflective GMs. In this paper, we focus our research on the manipulation of EM wave reflection using reflective GMs under normal incidence both theoretically and experimentally. The design theory of reflective GMs...
A new algorithm for ray tracing that called “minimum included angle algorithm” was proposed in order to analyze airborne antenna layout optimization. First of all, the discrete surface was divided into triangular meshes to generate surface grid data that accorded with the format that was required in this article. The “minimum included angle algorithm” was used to process the data mentioned above....
Wireless communication is very important for the safety production in coal mine. In this paper, the novel analysis method for polarization modes on wireless communication in coal mine tunnel using reflection coefficient and transmission coefficient is presented, and we suggest packet-level adaptive interleaved forward error correction(I-FEC) at the application layer for improving the communication...
In this paper, the propagation characteristics of radio wave is studied in tunnel environments based on the method of SBR/Image (Shooting and bounding ray tracing/Image). An agreement is achieved by a comparison of simulated results and measured results. The formula of field strength considering polarization has been derived. Then the tunnel physical model has been set up. Some propagation parameters...
Appling the passive vector radiate transfer equation to build the mathematical model of single layer from random distributed spherical particles. Then the Eigen value and Eigenvector method is used to calculate the radiate brightness temperature of MIE particles and Rayleigh particles. The characteristics of the passive radiation of these two kinds of particles are observed and studied by analysis...
The propagation properties of electromagnetic wave through chaff clouds are investigated. The orientation characteristics of chaffs in atmosphere are analyzed and a modeling method of directional distributions of chaffs is introduced. The orientation distributions of chaffs in polarimetric coordinate systems are thereupon obtained. Using the Einarsson solution, we calculate the forward and back scattering...
The transition radiation of charged particle moving with a constant velocity perpendicular to the axis of regular waveguide filled with anisotropic magneto dielectric medium is considered. The wave equation and the analytical expressions for the transverse-electric (TE) filed are obtained. The energy of transition radiation of moving particle is calculated. The conditions for the appearance of the...
Recently, researches on wideband wireless communications have been investigated intensively. With the progress of wideband wireless communications, DOA estimation technique for wideband incident waves has been also required. The history of high-resolution wideband DOA estimation started several decades ago. However its standard technique is not developed yet. In this report, we have proposed a new...
This article acquires the microwave imagery of target through simulation, bases on ISAR imagery of complex target, and adopts the CLEAN method to extract the strong scattering point of target imagery; meanwhile, combine the non-uniform illumination under missile-target encounter conditions, respectively obtain the distribution parameters of target scattering points at various miss distance, providing...
A large number of numerical methods have been proposed and continue to be developed for solving electromagnetic structure problems. This paper presents a new look at these numerical methods and a way of unifying them with the node-based method of weighted residuals (MWR). As a result, a unifying approach to constructing of numerical methods is shown. It can then be applied to develop new numerical...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.