A Research On L-band Vehicle Mounted Multimedia Mobile Satellite Antenna

While scooters have become an increasingly indispensable part for people lives,the requirements of security,multi-function,intelligent and so on for car are higher and higher.As an important part of receiving and transmitting signal,antenna plays an important role in the realization of multi-function(such as real-time positioning,workshop communication,vehicle entertainment)and intelligence.So the related research of vehicle antenna has become a necessary topic.The performance characteristics of vehicle antenna,such as miniaturization,low elevation,high gain,conformal with the vehicle,adapting to the vehicle application environment of different installation positions,are the important research directions.In this paper,the L-band mobile satellite antenna is researched and designed,especially for the application environment installed on the roof,in order to design a more suitable characteristic vehicle antenna for the vehicle environment.The main research work of this paper is as follows:1.In view of the unique vehicle environment different from the ground and other antenna applications,it is analyzed that when the roof shark fin is installed,a metal roof similar to a huge metal surface will have a huge impact on its internal antenna.In order to so solve this problem,an anti-metal high-gain circularly polarized antenna improved on the basis of a circularly polarized microstrip antenna was designed.This design not only avoids the negative impact of the roof metal on the performance of the antenna,but also makes reasonable use of the metal surface as part of the antenna structure to make an appropriate structural design,thereby achieving high gain performance of the antenna.2.For L-band satellite broadcast vehicle applications,a low-profile broadband circularly polarized antenna is designed based on the quarter-mode substrate integrated waveguide(QMSIW).The antenna uses a novel QMSIW cavity quaternion array to provide 90° sequential rotation excitation for the radiation patch to achieve circular polarization.This form of feeding introduces another resonant mode,effectively expanding the antenna bandwidth.At the same time,it simplifies processing compared to coaxial feed without soldering,while maintaining floor integrity compared to coupled feed.Then,the integrity of the antenna ground plate is used to place the active module above the dielectric substrate,which reduces the antenna profile from the overall angle of the antenna and is beneficial to the electromagnetic compatibility problem.3.Under the background requirements of vehicle multi-function requirements,two antennas of different frequency bands and different functions that use QMSIW cavity sequential rotation feeding,are integrated together.The antenna floor integrity and radiation patch center position retained by the QMSIW cavity feeding method are always the minimum point of the electric field strength,which provides a feasible condition for this integration.Because the feeder feeds the upper antenna through the radiation patch,it will not affect the performance of the lower antenna.Moreover,the radiation patch of the lower antenna is used as the ground plate of the upper antenna,that is,the lower metal plate of the QMSIW cavity,which reduces the overall utilization space of the antenna and is beneficial to the realization of vehicle multi-function.