| In recent years, with the development of wireless communication network, wirelessrecognition system, wireless intelligent network and other new technologies, the wirelessapplication domain continues to expand and the scarcity of frequency band resourceincrease with days. There are occasions that interference between devices occurs due to theoveruse of frequency spectrum. The influence of electro-magnetic environment hasreceived world-wide attention. So the importance of spectrum monitoring has becomeincreasingly prominent due to these factors and it is meaningful to design variouswide-band monitoring antenna with own features especially design and implementation ofantenna with miniaturization, wide-band, portable is the vital part of frequency monitoring.In addition, the establishment of wireless frequency spectrum monitoring system withfeatures of remote monitoring, making record and data processing has become the focus ofgovernment and industry.The design of wide-band monitoring antenna and automatic frequency spectrummonitoring system have been studied and explored in this paper. Based on former research,a series of passive wide-band antennas that are used for frequency monitoring aredesigned.In this paper, the specific work includes the following aspects:Firstly, study of two fabric antennas is conducted. Fabric antenna has merits like lightweight, portable and compressible. In this paper a VHF band load added fabric antenna isdesigned with height of500mm. The measured result shows that the bandwidth meets therequirement of VHF band requirements and verifies the possibility that fabric material canbe used in low band application. And then a fabric ultra-wideband antenna is fabricated.The bandwidth is from2GHz to8.8GHz which can be used in high frequency bandfrequency spectrum monitoring.Secondly, two types of3D wideband antennas are designed. The dual-frequency lowprofile antenna is based on PCB technique and silent element theory. The band spans from842MHz to1049MHz and from2.4GHz to2.5GHz. This antenna is with omni-direction radiation pattern with height of nearly1/8wavelength of low band. On the basis of thisstructure and load added theory, a VHF band application antenna is designed andfabricated.-10dB bandwidth spans from34MHz to345MHz and it is withomni-directional radiation pattern. The height of this antenna is300mm. So features ofbroadband and low profile at VHF band are realized.At last a frequency spectrum monitoring system is developed. This system is a PCterminal software based on C/S architecture which realizes functions of data fetching,display and analysis. This system helps to ease burden of test staff. And at the same time ageographic position based electromagnetic radiation intensity presenting platform isdesigned. This platform provides supervisor tools in macroscopic analysis. |
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