Hou Jianqiang

Research on the method for producing a highly linear FMCW signal based on the PLL circuits

This paper describes a method for directly generating FMCW signal based on the PLL circuits; mainly by changing the PLL systems frequency divider ratio N rapidly and producing a corresponding control voltage to control VCO to output the FMCW signal. The key of this method is the transition period Δt of divider. Set up simulation model in ADS2011 to simulate, get the conclusion that the smaller the transition period Δt, the better the linearity of the FMCW signal than verify this conclusion by measurement. This method has many characteristics like high reliability, easy to adjust, mature circuit structure, etc.

An improved design of microstrip slot antennas using ring structure

This paper presents the simulation of a special microstrip slot antenna, which is formed by cutting a ring slot around a line slot in the patch. The side lobe levels were minimized and the back radiations were reduced by using a reflector at λ/4 distance from the geometries model. According to the special configuration of the slot, it estimates that the special microstrip slot antenna possesses the similar characteristic of slot antenna, such as wide bandwidth. Some simulations have been performed and the results show that gain of the special microstrip slot antenna is better than the normal slot antenna in certain conditions. It affords a new approach to design microstrip slot antenna.