Research On SIW-based Slot Array Antenna

Substrate Integrated Waveguide?SIW?is widely utilized in the design and manufacture of microwave and millimeter wave devices such as antennas,filters,power splitters,and so on for its advantages of easy integration and low loss.In this paper,SIW structure was combined with antenna and filter.Two slot antennas based on SIW structure were designed.Also,a dual band slot array antenna is proposed and modified.What's more,a filter and a filtering antenna combining SIW structure and DMS were designed.Two slot antennas,which are respectively operated in the X and Ka bands,based on SIW structure were designed in the first part.The antenna structure is composed of two dielectric substrates.Four rows of metalized vias are employed on the lower substrate to form a SIW cavity.A feeding slot and several radiation slots are etched on the middle metal layer.Energy was fed by the microstrip printed on the upper substrate,coupled into the cavity of the lower layer through the feed gap and forming a TE₂₀ mode in the cavity.The two antennas operate at 9.38 GHz to 9.6 GHz and 35 GHz to 39.52 GHz,respectively,and one can achieve a fairly wide bandwidth in the Ka band.The second part is based on the above two slot antennas,a dual-frequency slot array antenna was designed and the feed structure is basically the same as the above antenna,only the design and layout of the radiation slot is different.In the original design,we studied the coupling between the two frequency bands,and we can see that there is good isolation between the gaps in different frequency bands where the influence between the two arrays is small.The antenna can achieve radiation from 9.35 GHz to 9.6 GHz and 28.56 GHz to 40 GHz.However,it can be seen from the pattern that the main radiation direction deviates from the normal direction of the gap on Ka band.In the subsequent design,the length of the waveguide cavity is extended,and the size of the feeder is appropriately adjusted to improve the performance of the radiation pattern.The number and arrangement of the radiation gaps are also rearranged to further improve the two frequency bands and isolation between the gaps.The improved antenna was fabricated and tested.The measured 10dB impedance bandwidth was 9.76 GHz to 10.25 GHz and 26.7 GHz to 40 GHz.Both of these bandwidths were weak less compared with the simulation results.In addition,the measured gains at the two selected frequencies reached 10.9 dBi?10 GHz?and 9.05 dBi?37 GHz?,which were only 0.05 dBi and 0.161 dBi lower than the simulation results,respectively.General speaking,the simulated and measured results are in good agreement.The third part is based on the substrate integrated waveguide,a filter was designed assembling this structure and the defect microstrip structure.Since only electromagnetic waves with a frequency higher than the SIW cutoff frequency can propagate in the SIW structure,the SIW structure has a similar"high pass"characteristic,and the defective microstrip structure has a"low pass"characteristic,so a bandpass characteristic is available when the two are combined.Using this principle,a bandpass filter was designed,and then the waveguide slot array antenna is loaded to complete a filter antenna,which can radiate in the 11.52 GHz¹7.23 GHz band.With a relative impedance bandwidth of 39.78%,the in-band gain is flat.