Defence Research Agency

About: Defence Research Agency is a based out in . It is known for research contribution in the topics: Synthetic aperture radar & Radar. The organization has 1211 authors who have published 1109 publications receiving 31542 citations.

Improved six-port reflectometer based on symmetrical five-port junction

Abstract: A waveguide six-port reflectometer incorporating a symmetrical five-port junction is described that covers the frequency range 26.5–40 GHz. Its performance is compared with an earlier design, illustrating the improvement in sensitivity and stability that is available from the new configuration.

Modelling of spanwise mixing in compressor through-flow computations:

Abstract: Although three-dimensional Navier-Stokes computations are coming into use more and more, streamline curvature through-flow computations are still needed, especially for multistage compressors, and where codes which run in minutes rather than hours are preferred. These methods have been made more realistic by taking account of end-wall effects and spanwise mixing by four aerodynamic mechanisms: turbulent diffusion, turbulent convection by secondary flow, spanwise migration of aerofoil boundary layer fluid and spanwise convection of fluid in blade wakes. This paper describes the models adopted in the DRA streamline curvature method for axial compressor design and analysis. Previous papers are summarized briefly before describing the new part of the model-that accounting for aerofoil boundary layers and wakes. Other changes to the previously published annulus wall boundary layer model have been made to enable it to cater for separations and end bends. The resulting code is evaluated against a range of experimental and computational results.

A review of the interference resistance of sps gps receivers for aviation

Abstract: Demonstrations of GPS-based approach and landing systems have caused many potential users of the Microwave Landing System (MLS) to question whether it is appropriate to install such a costly system. An investigation of the resistance to electromagnetic interference of Standard Positioning Service (SPS) C/A-code GPS receivers in aviation environments demonstrated their susceptibility to inband noise; for example, 1 W of radiated power jammed an airborne receiver at ranges in excess of 30 km. Although resistance to out-of-band interference is significantly greater, transmissions from communications systems in frequencies adjacent to the GPS bands present considerable problems for GPS reception. Consequently, the use of C/A-code receivers for applications requiring high reliability and integrity, such as approach and landing, must be questioned.