Research Of Twin-whip Antenna In Very High Frequency

Antennas play a very important role in the modern communication system. In order to keep secret in military communication, communication technologies of Frequency-Hopping and Spread Spectrum have been widely used in the Communication equipments such as VHF radio , which makes broadband and high gain antennas are more demanded. The way how to broaden bandwidth and increase gain of antenna with multi-dipole structure is one of main content of VHF antenna researches。This paper mainly researched omni-direction broadband antennas in very high frequency (VHF) with a lot of theoretical and experimental studies. The method of analysis such as MoM and electromagnetic simulation software are used to complete the design and simulation. The author's major contributions are as follows:1. The transmission characteristics of ultrashort wave communication and antenna broadband technology was introduced and analyzed.2. The electrical characteristics of dipole antenna are analyzed. Author change the feed point location of antenna, which constitute non-symmetrical dipole antennas. These non-symmetrical antennas are simulated and compared according to different extent of dissymmetry.3. For Specific project-oriented applications, the structure and dimension of twin-whip antenna is designed and optimized, including the length of antenna, radius and the antenna spacing. The analysis focus on relation between the pattern,gain and antenna spacing. Finally, a reasonable size is proposed.4. A broadband matching network are designed and optimized by the genetic algorithm to realize a VSWR claim over 30~88MHz.5. The simulation of twin-whip antenna, the manufacture of sample and experimental test are completed,include the test of vswr and the performance of antenna at the distance of 2km and 30km.To make use of above these ways a twin-whip antenna of non-symmetrical dipole with matching network loaded are designed. The omni-directional antenna can realize VSWR<3, and have a good gain. At last, miniaturization of twin-whip antenna is researched because the size is too large. Author proposed a monopole with a parasitic helix as the element of twin-whip antenna, which provide a new thought for the future work and research.