Research On The Key Technologies Of Integrated Front-end Of W-band Anti-collision Radar

Due to the complex geographical environment and weather conditions, low altitude aircrafts, such as helicopters, are easy to be crashed. This causes serious casualties and property losses. Millimeter-wave anti-collision radar has the ability to work in various weather conditions. The radar can detect the collision threats in front of the low altitude aircraft in real time and provide the risk warning. Thus, it provides security assurance for the low altitude aircraft. In order to enhance the resolution, achieve miniaturization, and improve reliability, anti-collision radar, which is based on W-band solid-state integrated front-end, is one of the focus in recent years. In this dissertation, the theoretical analysis and experimental study of the key components of front-end(include W-band GaAs chip, W-band integrated transceiver module, and W-band reflectarray antenna) are carried out. Specific research contents are as follows.1. The noise characteristics of pHEMT GaAs low noise amplifier are studied. Small signal transistor model(SSTM) and its error are analyzed. Using the two-port linear network synthesis method, a new optimization method of SSTM of “T network + SSTM +T network” is used to reduce the transistor’s de-embed and parameter errors. A W-band low noise MMIC amplifier is designed with the optimization method. At the same time, the efficiency of Ga As balanced quadrupler is studied. Using the nonlinear characteristics of the diode, the working mechanism of the balanced quadrupler is analyzed from two operation modes(one is frequency multiplication mode, and the other is mixing mode). The frequency multiplication efficiency, using different input and output harmonic reflection networks, is evaluated. And a W-band GaAs quadrupler chip is developed. The development of the W-band MMIC chips provides a prerequisite for the development of W-band anti-collision radar.2. In this chapter, the integrated transceiver module is developed based on the W-band chips above. It focuses on the key processes and passive circuits of the module. First, the gold wire bonding between plane devices is deeply analyzed. And a good-performance gold wire bonding method is obtained. Considering the mutual coupling of the two wires, a static model of the W-band gold wire bonding is obtained by theoretical calculation and full wave electromagnetic simulation. Second, in order to improve the electromagnetic compatibility of the integrated front-end, the transmission characteristics of substrate integrated waveguide(SIW) are studied. The broadband vertical transition structure between the air-filled rectangular waveguide(AWG) and SIW is realized by using the voltage probe and current probe. The electromagnetic field mode transition(In turn, the AWG TE01 mode the voltage probe the quasi coaxial TEM mode the current probe the SIW TE01 mode) is clearly demonstrated. Third, in order to improve long term reliability of the integrated front-end, the AWG is recommended to be sealed. Using the direct coupled filter theory and the two-port linear network synthesis method, the RT/Duroid5880 waveguide window is equivalent to the parallel LC resonator and the quarter-wavelength straight waveguide is equivalent to the J converter. By using the direct coupled filter network structure(dielectric resonator-waveguide J converter- dielectric resonator), a W-band broadband low-cost compact double-layer waveguide window is developed. Using the key processes and passive components, the W-band frequency multiplication module and the W-band low noise receive module are developed. The modules provide the necessary conditions for the miniaturization of W-band anti-collision radar.3. Taking into account the special requirements for anti-collision radar antenna, the chapter focuses on the W-band reflectarray antenna. A design method to reduce the sidelobe level(SLL) of the offset reflectarray is proposed, namely when the main beam direction is consistent with the specular reflection direction, the antenna SLL will be reduced. And the large radiating element area also improves the SLL. Finally, a W-band reflectarray antenna is developed.4. MMIC chip, integrated transceiver module and reflectarray antenna are used to integrate a set of W-band front-end. The super-heterodyne FMCW radar front-end architecture is used to avoid the disadvantages, such as the blind area of the pulse radar, the zero frequency signal interference of zero intermediate frequency FMCW radar. Through the far field testing, the theoretical analysis and design methods are verified.