Radiation Patterns of Antennas Installed on Aircraft.
Abstract : This thesis presents a study of radiation patterns for low-gain antennas installed on aircraft. With the aid of the computer program APATCH, a simulation of the radian on patterns for a given antenna located at various points on an aircraft structure can he evaluated. The program uses a technique referred. to as Shooting and Bouncing Rays (SBR), which is valid for structures that have typical dimensions of ten wavelengths or more. A Cessna 172 aircraft with a quarter-wavelength monopole antenna and an F-18 aircraft with a telemetry antenna are analyzed.
We propose and analyse three different power selection schemes for slotted ALOHA random access protocol operating under multiple power levels. Through analysis and numerical examples we demonstrate that these schemes can significantly improve the performance of slotted ALOHA, in terms of throughput and stability, under heavy load. The proposed schemes are truly distributive in nature and can be easily implemented in wireless access systems without requiring any centralised control.