Radome Transmission Characteristics Of The Asymmetric Thermal Environment Research

Radome is an equipment which protects antennas from the atrocious conditions. It is used widely in radio system such as aviation, spaceflight, missile, radar, communications, navigation and so on.Radome is designed to protect the antennas from the external environment. However, radome is interfering with the electromagnetic radiation of antenna, which may result in significant degradation of antenna performance, cause transmission attenuation and beam deflection. Beam deflection produces boresight error (BSE) which is defined as angle shift between viewing direction and true direction. Boresight error slope (BSES) is defined as the ratio of angle shift to the tracing angle of the antenna.For strategical missile, the main task is to attack the target accurately. To ensure the reliability of tracking the target, signal attenuation and boresight error must be predicted accurately. The missile with its radome is at high temperature during the entrance. due to aerodynamics heating process, The high temperature cause air ionization and ablation of the radome, so the radome is at unsymmetrical heat environment, its electrical properties vary with different parts of the radome. For analyzing, a new model is bulit, the radome is divided into parts along length, periphery, thickness of radome wall and each part with different dielectric constant.Based on unsymmetrical heat environment, boresight error, boresight error slope and transmission coefficient of a specific shape radome have been calculated with indirect ray method. Indirect ray method contains the following steps: The receiving plane wave field intensities on an adapted closed surface encloseing the antenna is calculated and then the radiation field of the antenna on the same closed surface is obtained from the given antenna. After using Lorentz reciprocal theorem, the far field patterns with and without radome are gotten. The radiation patterns at different scan angle from -20 to 20 degree are presented, and the angle difference between the maximum / minimum field points of their main beam shows the BSE of the radome.At different frequencies, the radiation from the antenna has been discussed when azimuth scan angle ranges between -20 degree and 20 degree. The relationship between...