| Nowadays band has been widely used in wireless communications due to its better signal to noise ratio and high efficiency. However, Because of its low frequency and long wavelength, VHF/UHF antennas have to be made big size conventionally and have been unable to adapt to the development of current wireless communication systems. At the same time, frequency-hopping and spread-spectrum techniques are widely used in modern communication systems, the rate of frequency-hopped becomes more and more rapid, and the range becomes more and more wide. So narrow-band antenna can not meet the requirements of modern communication systems. The requirement of broadband miniaturized antennas for society become more and more urgent and important.In this paper, it does a great deal of theoretical analysis and experimental research in the VHF/UHF antennas at first, then, it uses the CST simulation software to simulate several types of antenna and optimize the antenna parameters. Finally two antennas were produced and tested. The results are very well. The work done in this paper can be summarized as follows:1. A brief summary and analysis of technology development of the current broadband miniaturized antenna are done by this thesis. And this paper analyzes several antennas’electrical properties related and summarizes their advantages and disadvantages.2. Monopole antenna, equivalent to a dipole antenna, resistive loading antenna and the sleeve antenna has been improved and simulation by using CST Microwave Studio simulation software. And it gets better antenna electrical performance parameters.3. According to the simulation results, this thesis selects two better antennas. Resistive loading antenna and new sleeve antenna were produced and tested the electrical properties through a series of tests. The measured results and simulation results are basically same.4. The summary of the whole thesis is given and some possible key techniques of the antenna design are predicted. |
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