Helicopter Platform On The Vhf Band Antenna Miniaturization And Theoretical Research

As the port to receive and transmit radio waves, antenna is an indispensable part of the wireless communication system. Its structure and performance play a key role in communication quality. The space reserved for each of the antennas is limited because of the miniaturization and integration of airborne equipments and increase in the number of communications equipments. Coupled with the requirement that the antenna installed on the aircraft can not change its aerodynamic performance, there is a higher and higher demand for the miniaturization of antennas. In order to adapt to these developments in airborne communication, the development of high-performance, miniature VHF antenna becomes very urgent and important in theory and applications. Being associated with the research project"Miniaturization of VHF antenna on helicopter platform", this thesis is proposed a kind of antenna, which has a small size (about 0.1λ,λis the operating wavelength), low profile (about 0.03λ) and high gain (greater than 3dB), its performance is omni-directional in the horizontal direction. The design is developed according to the characteristics of airborne antenna design, the characteristics and research methods of microstrip antennas as well as miniaturization technologies. The test results verify the correctness of simulation results. Besides, the influence of structural parameters on the resonant frequency and certain properties are also studied, the analysis results are showed. The design of the antenna element will be followed by an integrated modeling of helicopter carrier and the antenna. The compared results and the physical analysis are also showed after the approximate calculation. The main contribution of this thesis and creative achievement are outlined as follows,(1) The current research status of airborne VHF antennas has been summarized, and characteristics of the airborne antennas, the key factors and the technical difficulty needed to be considered in the design have also been analyzed in details. It can provide some theoretical basis to the future study.(2) A kind of VHF low-profiled and small antenna is designed by the use of the short wall and bending technology in the case of limited size. The bending technology can increase the effective electrical length of the antenna and reduce the size of antenna. This is not only meaningful to the practical application, but also to the concept of the miniaturization of antenna on VHF band.(3) The detailed physical analysis and the study of structural parameters are done, which can provide theoretical direction to progressing and tuning.(4) The influence of the helicopter platform on the performance of antenna has been studied in numerical method. The results can provide foundation to the practical engineering applications.