Research And Design Of Coaxial Slot Broadcasting TV Transmitting Antenna

With the development of the TV industry,the requirements of quality for TV images get higher and higher,the quality of the antenna system,the choice of the site,and the rational use of the band will directly effect the quality of the image.Due to the large transmission power,slight reflection at the antenna end will damage to the end of the transmitter,and the return loss is generally required to be greater than 20 dB(Grade C).Therefore,the research and design of broadcast television transmitting antennas is great significance.The coaxial slot antenna has the advantages of integration,simple installation and low cost,it has broad application prospects in the field of broadcast television transmission.The research topic of the thesis comes from the antenna design project proposed by Liaoning Putian Digital Co.,Ltd.The project need to design of UHF and VHF band coaxial slot antennas.The main work of the thesis is as follows:(1)In order to verify the feasibility of the method for coaxial slot antenna design,first design a 2.45GHz coaxial slot small antenna.The outer conductor of the antenna has a cylindrical shape,and the inner conductor has a stepped shape,and on the outer conductor has a longitudinal slit along the outer conductor.The simulation results show that the antenna roundness can reach 1.5dB when the center frequency of the antenna is 2.45GHz,and less than-25dB in the range of 2.43GHz?2.46GHz.Physical processing and testing.The test results showed that the center frequency of the antenna operation was-42 dB at 2.45 GHz and the roundness was 1.498 dB.Proves the feasibility of the coaxial gap applied to TV transmission.(2)Designed a coaxial slot broadcast television transmitting antenna for UHF band.The outer conductor and the inner conductor of the antenna has a rectangular cross section,and six longitudinal slits are formed on the outer conductor and form an antenna array.The simulation optimization results show that the antenna roundness reaches 1.5 dB when the center frequency is 600MHz,and reflection coefficient less than-25dB in the frequency range of 580MHz-614MHz.The in-band gain is above 8dBi and the maximum gain is 12.05dBi.The technical indicators are satisfied."Technical Specifications of TV and FM Radio and Television Antenna Feeder System" issued by the Ministry of Radio,Film and Television.(3)Designed a 4-slot coaxial slot antenna operating in the VHF band.The simulation results show that the reflection coefficient less thans-25dB in the range of 200 MHz?236 MHz,and the antenna gain is 8.1 dBi.Then,physical processing and testing.the test results show that the reflection coefficient is less than-25dB in the range of 200MHz?235MHz...