| The waveguide slot antenna has the advantages of small size,high gain,high mechanical strength,and easy control of the excitation current distribution.Substrate integrated waveguide(SIW)is a new type of planar transmission line,which has the characteristics of a waveguide and can be implemented on a printed circuit board.The SIW slot antenna has the advantages of the waveguide slot antenna and the substrate integrated waveguide,which has become one of the hotspots in the field of antenna research.For the traveling wave structure of the SIW slot antenna,it is usually necessary to connect a matched load at its terminal to reduce the reflected wave.Therefore,only a part of the input power is radiated by the slot,and a lot of energy is absorbed by the load,making the SIW slot antenna less efficient.In order to solve the problem of low efficiency of the existing SIW slot antennas,this thesis focuses on how to construct the topology of SIW slot antennas to improve energy utilization.The main works completed include:(1)A three-way SIW slot antenna with serial-parallel hybrid feeding is designed.The antenna has a transverse slot structure,and the slot distance is much smaller than the operating wavelength.When the longitudinal size is not significantly increased,by loading a T-junction and a curved structure at the end of the middle SIW slot antenna,the effective integration of the three-way SIW slot antenna is realized to improve the antenna energy utilization.In addition,a vertical reflector is added at an appropriate position at the rear end of the antenna,so that the backward radiation and the forward radiation are combined into a single main beam to improve the antenna gain.The measurement results show that the energy utilization rate reaches 89.2%at 9.4 GHz which significantly improves the energy utilization compared with the single-way antenna,the direction of the main lobe is ?=52°,the gain is 1 1.8 dBi,and the antenna radiation characteristics are good.(2)A four-way SIW slot antenna with parallel feed is designed.A l-to-4 SIW power splitter formed by cascading T-junctions and Y-junctions is used to feed the four-way traveling wav e SIW slot antennas in phase,and a SIW combiner is used to connect a single matched load.In addition,the sinusoidal envelope distribution of the slot lengths of the SIW slot antenna is adopted to expand the spatial scanning range.The measurement results show that the operating frequency band is shifted to a higher frequency.In the frequency range of 9.52?9.73 GHz,|S11|<-10dB,|S21|<-9.1dB,the energy utilization rate reaches 87.6%at 9.66GHz which significantly improves the energy utilization compared with the single-way antenna.The direction of the main lobe at 9.6 GHz is ?=56°,the gain is 12.3 dBi.(3)A SIW slot antenna based on energy self-recycling structure is designed.The antenna includes a single-way SIW transverse slot antenna,a phase delay line,and an unequal power microstrip hybrid.The microstrip hybrid makes the energy at the output port of the traveling wave SIW slot antenna return to the input port,which has the effect of signal combination and energy superposition.The measurement results show that at 9.4 GHz,the direction of the main lobe is ?=57°and the gain is about 5.74dBi.In the case of single-way,energy utilization still reaches up to 91.4%. |
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