| With the continuous updating of communication technology,the significance of the antenna in wireless system is growing.The modern radar system has the capacity of early warning,electronic warfare,navigation,communication,therefore,it has stringent requirements for the performance of the antenna system such as a wide range of bandwidth,low profile,miniaturization and so on.In recent years,tightly coupled antennas have attracted wide attention of scholars both at home and abroad,this is a new design method different from that of traditional array antennas.Due to the long slot antenna has special value.Combined with the relevant literature at home and abroad,two long slot antennas with ultra wideband characteristics have been designed in this thesis by utilizing the mutual coupling effect among units.The content follows these step.We have a research about the theory of UWB antenna and long slot antenna in depth.The advantages have been analyzed and compared between tightly coupled antenna and traditional array antenna.The design of single feed slot antenna is the starting point of research.The design method of antenna is achieved by increasing the length of the gap and increasing the number of feed points,and a wideband antenna with an approximate four multiple frequency is designed and achieved by selected triple wavelength long slot and eight parallel feeding modes.Throughing processing,production and testing show that the impedance bandwidth of the antenna is 1.05GHz-4.07 GHz,which is close to 4: 1.Furthermore,we have a research about infinite long slot array antenna,and a low-profile dual-polarized long slot antenna has been designed.The orthogonal long slot was coupled with the mutually orthogonal bowtie antenna and then achieved the ultra-wideband.The low-profile of the antenna is achieved by loading on the metal reflecting floor using ferrite and periodic metal sheet structures.The results illustrate that the active voltage standing wave ratio is less than 2 in the frequency range of 0.11GHz-7.58 GHz,so the antenna has the ultra-wideband characteristics.This antenna has a profile of 26.5mm,nearly 1/100 of the wavelength at the lowest operating frequency,so the antenna has extremely low profile. |
