| Antenna is a key component in wireless communication systems.With the rapid development of wireless communication systems,the communication systems require more and more antennas.Beam scanning antennas can replace multiple antennas with one antenna array and problems such as multipath fading and cochannel interference can be solved.So beam scanning antennas are widely used in microwave communication systems,missilecontrol systems,satellite communication systems and radar systems.In this paper,three kinds of beam scanning antenna arrays for Q-band application are designed.The main work and innovations are as follows.Firstly,Substrate Integrated Coaxial Line(SICL)is designed and manufactured.The measured S11 is less than-13 dB and the insertion loss is less than 0.09 dB/mm in the range of 40 to 50 GHz.Butler matrix is designed based on SICL structure and the components of Butler matrix including 3-dB coupler,crossover,45-degree phase shifter and 0-degree phase shifter are simulated and optimized.At 45 GHz,the power distribution of the four output ports are within-6.6±0.8 dB.When the four input ports are fed in turn,the phase differences between the adjacent output ports is-45° +6°,45° ±6°±-135° ±11° and 135° ±11°,respectively.The designed SICL Butler matrix achieves low loss and specified phase differences.It can be used as the beam-forming network of antenna array.Secondly,a broadband,high gain and high integration coupling fed beam scanning antenna array is designed and fabricated.The back-cavity patch antenna element made of a radiation patch,via holes and ground plane consists of a 1×4 series-fed sub-array.Four sub-arrays are arranged symmetrically to reduce side lobes and fed by SICL Butler matrix.The size of the antenna array is 6.3?0×7.10?,and the measured impedance bandwidth is 21.8%.The beam direction is-28.5°,-14.1°,18.4° and 35.6?,and the corresponding gain is 13.11,13.88,14.02 and 11.78 dBi,respectively at 45 GHz.The measured results and the simulated results agree well.Then,a compact probe-fed beam-scanning antenna array is designed.The antenna sub-array is composed of compact parallel fed 2×2 circular patches and back cavity.Four sub-arrays are linearly arranged in equal distance and fed by SICL Butler matrix.The area of the antenna array is only 6.3?0×5.2?0,,and the simulated impedance bandwidth is 21.1%.The simulated gains of four beams is between 13.12 and 13.94 dBi,and the beam scanning angle is±320°at 45 GHz.Finally,a slot beam scanning antenna array with high gain,low side lobe and wide scanning range is designed.The slot element is excited by a vertical short branch added to the SICL.The slot element is evenly distributed on both sides of the SICL to form a 1×8 sub-array.Four sub-arrays are linearly arranged and fed by the SICL Butler matrix.Compared with the other two antenna arrays,the side lobes of this antenna array are reduced by 4.5 dB and 4 dB,respectively,and the coverage range of the antenna beam is±460.The area of antenna array is 6.3 ?0×7.6?0?,and the simulated impedance bandwidth is 18.9%.The simulated gain is between 14.81 and 15.99 dBi at 45 GHz. |
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