| Regularly slitting on the waveguide to form a slot antenna,when the slot is formed into an array,higher gain and narrow beam can be easily obtained.Meanwhile the substrate integrated waveguide completes the transformation from non-planar structure to planar structure.lt not only has the characteristics of high quality factor of rectangular waveguide,but also the small size and low cost of microstrip,especially when the microstrip line is applied to the millimeter wave frequency band,the loss is too large.Therefore,when the working frequency is W band,the substrate integrated waveguide slots antenna is easy to have the characteristics of compact structure,high efficiency,low cost and light weight,etc.SIW slots antenna array has attracted more and more attention and has been widely used in radar,navigation,detection and other directions.With the development of modern science and technology,the antenna research has also completed the process from the low frequency to the high frequency.The higher the frequency is,the greater the loss will be.therefore,the higher the requirements for the antenna structure will be.In this paper,a substrate integrated waveguide slots array antenna at W band is designed.The radiation part and the feeding part of the structure are studied based on the substrate integrated waveguide and the waveguide slots antenna.The main work of this paper is as follows:1.Design of the W-band SIW linearly polarized slots antenna array:A 4×4 substrate integrated waveguide linearly polarized slots antenna array is designed.The design principles of the substrate integrated waveguide are discussed before the slots antenna is designed.the design of slots antenna array is mainly divided into radiation slots antenna and coupling slots antenna.The radiated slots antenna adopts the waveguide broad wall longitudinal offset slot,which is similar to the shunt admittance in the equivalent circuit,and can radiate energy out of the slots better.The coupling slots anterna array adopts the waveguide broad wall and the center tilting slot,which is similar to the series impedance in the equivalent circuit and can be used to feed the antenna structure.The above two kinds of slots antennas are designed and optimized by 3D simulation software,and the ideal results are obtained.When the working frequency is 94 GHz,the reflection coefficient of the linearly polarized SIW slots antenna array is-30.1 dB,the antenna gain is 16.8 dB,antenna sidelobe level is 19.5 dB,Half-power beam width is 380.2.Design of the W-band SIW circularly polarized slots antenna array:For a linearly polarized antenna,once the receiving direction is inconsistent with the transmitting direction of the antenna,there will be a great loss of energy,in practical application,antenna efficiency maybe very low in the face of complex terrain conditions and extreme weather conditions,and the antenna efficiency will be very low in the face of relatively complex terrain conditions and extreme weather environment.Therefore,a layer of circularly polarized symmetric oscillator is installed above the antenna radiation layer,and a circularly polarized wave is formed by changing the phase and direction of the electric field.Through simulation,the minimum reflection coefficient of circularly polarized SIW slots antenna array at 92.9 GHz is-32.5 db,and the bandwidth of-10 db of the antenna is(92.5.95.15)GHz.When the working frequency is 94 GHz.the gain is 16.65 dB,the sidelobe level of antenna is 12.6 dB,the half-power beam width is 80°.the axial ratio of the circularly polarized antenna is 1.1.dB.3.Design of the transition structure and experimental verification of the antenna processing:In order to complete the conversion from substrate integrated waveguide structure to standard rectangular waveguide,this paper designs a transition structure to connect with the antenna,and finally,the experimental verification and analysis of the antenna object were carried out. |
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