Research On Miniaturization Of Microwave Passive Components Based On Slow-Wave Structure

With the rapid development of modern microwave and millimeter wave circuit systems,wireless communication is closely integrated with people's daily lives.As people's demand for data increassing,there are higher demands on wireless communication systems.Miniaturization,low cost,multi-frequency/multi-mode,and easy integration with active systems have become the main research direction of modern communication systems.As a key component of modern communication systems,microwave passive components play a decisive role in miniaturization and high integration of the entire wireless communication system.Therefore,it is important to carry out research on miniaturization of microwave passive devices.With the trend of miniaturization of passive devices,this thesis discusses the miniaturization design of phase shifters and antennas.The research content was mainly divided into the following five parts:1)In this thesis,the guided wave characteristics of the Substrate Integrated Waveguide(SIW)and the Slow Wave Substrate Integrated Waveguide(SW-SIW)model were analyzed by theoretical analysis and simulation.Conclusions were: SW-SIW reduced the main mode cutoff frequency to 62% of SIW compared to SIW of the same size;With the same cutoff frequency,the lateral dimension of the SW-SIW reduced to 63.9% of the SIW;With the same cutoff frequency,the vertical dimension of SW-SIW reduced to 51.7% of SIW when the SIW reached the same phase shift amount as SWSIW;For SW-SIW as a whole,its overall area reduced to 33.1% of SIW.At the same time,the above conclusions were also verified through the physical processing test.2)The ferrite sheets were loaded based on SIW and SW-SIW,and the phase shift characteristics of the ferrite sheets were studied by high frequency simulation software HFSS.It was concluded that the phase shift of the SW-SIW phase shifter increased by 1100° compared to the SIW phase shifter with the same magnetic field offset of the same dielectric substrate of the same size.3)Through a theoretical calculation,a dedicated Dedicated Short Range Communications(DSRC)antenna was designed in HFSS.By adjusting the length and impedance matching of the radiating element of the antenna,the center resonance point of the antenna was 5.9GHz and the bandwidth was 5.7-6.2GHz.Through field testing,the antenna had a maximum gain of 5.3dBi over the operating frequency range and a half power lobe width of 360°.4)By adding a radiating oscillator to increase the resonance point based on 3),a 4G/LTE dual-band antenna was designed.Then,the length of the radiating element of the antenna is adjusted such that the center resonance point of the antenna was at 0.74 GHz and 2.3GHz,and the bandwidth was 0.68-1GHz and 1.75-3GHz.Through the external field test,the antenna gain was greater than 1dBi in the low frequency band,and higher than 2dBi in the high frequency band,and had better omnidirectional characteristics.5)In order to reduce the longitudinal dimension of the antenna in a fixed area,a slow-wave structure antenna was designed based on the 4G/LTE antenna.The antenna had an antenna gain of more than 0.5dBi in the low frequency band and more than 2dBi in the high frequency band by the external field test.Its longitudinal length was reduced by about 31%,achieving low profile and miniaturization.