Design And Research Of Millimeter-Wave Planar Slotted Array Antenna Fed By Ridge Waveguide

The slotted waveguide array antenna radiating unit operates as a slot cutting off the current flow of the main mode TE₁₀ on the inner wall of the waveguide.So that the electromagnetic wave in the waveguide cavity radiates to the outer space through the slots.The slotted waveguide array antenna is compact in structure,small in size,high in mechanical strength,and easy to control the radiating aperture distribution,so it can achieve high radiation efficiency,high gain and low side lobes.The millimeter wave spectrum is wide,the information capacity is large,the wavelength is short,the resolution is high,the penetration ability is strong,and the anti-interference ability is strong.The millimeter-wave slotted waveguide array antenna has both the advantages of frequency band and antenna type,and are more suitable for conforming to the carrier with the advantage of small size,and the application scenarios are very wide,including airborne,navigation,radar and other fields.Based on the theory of waveguide slot antennas,this thesis focuses on the analysis and design of miniaturized broadband antennas with high gain and low side lobes in millimeter wave.The main work is as follows:(1)Analysis and design of ridge waveguide structureFirstly,based on the advantages of small size and large bandwidth of the ridge waveguide,it is selected as the realization of miniaturization of the antenna.Taking the standard waveguide size of the same frequency band as the initial value,the ridge waveguide size is simulated and optimized.The ridge waveguide of the 94GHz antenna is designed firstly.The final cross-sectional area of the structure is 1.45mm²,which is 45%of the W-band standard waveguide WR10.The simulation results show that the working frequency band of the TE₁₀ mode in the ridge waveguide includes the entire W-band.In the same way,the radiating ridge waveguide of the 220GHz antenna is designed,and its cross-sectional area is 55%of the standard waveguide WR4.Both antennas use ridge waveguides to achieve miniaturization.(2)Analysis and design of array distributionThe number of array elements and the array arrangement are determined according to high gain and low side lobe requirements.Due to the large number of array elements,the Taylor synthesis method is selected for array distribution.And then a small model is established for parameter extraction,the array aperture distribution is converted into the slot structure parameter distribution,and the design of the antenna is finally completed.The simulation results show that the94GHz ridge waveguide slot antenna has a maximum gain of 32.17d B and a side lobe level of-25.3d B,and the 220GHz ridge waveguide slot antenna has a maximum gain of 32.7d B and a side lobe level of-18.1d B,all of which meet the requirements of high gain and low side-lobe requirements.(3)Analysis and design of array feedingThe single-layer and multi-layer feeding methods are introduced and analyzed.The 94GHz antenna is fed at the center by the coupling waveguide,attention is focused on analyzing and optimizing the width of coupling slots for feeding in the ridge of the radiating waveguide.Finally,it achieves a good match at 94GHz,the voltage standing wave ratio(VSWR)is 1.27.The working frequency band is 93.3GHz-94.5GHz,and the bandwidth is relatively narrow.For the purpose of optimizing the bandwidth,the 220GHz antenna adopts waveguide power division network to feed at the center.The waveguide power divider is formed by cascading three layers of H-plane waveguide T-shaped junctions.Through simulating and optimizing,the working frequency band is205.2GHz-230GHz,which improves the bandwidth performance.The design of two antennas with different frequency bands verifies the universality of the design method.