| With the continuous development of radar and communication,beam scanning array antennas have been widely studied and applied in these fields.The frequency scanning antenna is a typical traveling wave antenna in which the main lobe steers its direction with the change of the working frequency.Due to the superiorities of simple structure,large radiation mouth area and low production cost,it plays an extremely important role in applications such as radar detection,aerospace and automobile collision avoidance systems.However,the ordinary frequency scanning antennas have shortcomings such as narrow beam scanning angle,large size,heavy weight,etc.In view of the above-mentioned shortcomings,the research has been carried out on a miniaturized,low-profile,wide-angle scanning frequency scanning antenna.The main research contents of the thesis are as follows:1.Two spoof surface plasmon(SSPP)leaky wave antennas working in the Ku-band are designed.Both antennas are based on the equivalent circuit principle of the SSPP unit cell.By introducing interdigital stubs in the unit cell to enhance the coupling capacitance effect,the cut-off frequency of the cell dispersion curve is reducing.(a)Compared with the holetype SSPP unit cell,under the condition of the same cutoff frequency for the unit cell of antenna 1,the transmission line width is only 61.5% of the former,which reduces the lateral size of the antenna.At the same time,the analysis result of the electric field distribution of the antenna without any terminal load shows that its radiation performance remains unchanged.Therefore the terminal open circuit structure is adopted to further reduce the overall size of the antenna.In the bandwidth of 11?16GHz,the main lobe is continuously scanned from-54° to +6°,and the average gain can be up to 12 d Bi.It not only has the feature of wide-angle frequency scanning,but also achieves miniaturization;(b)To improve the band utilization rate of the frequency sweeping antenna,the antenna 2 is based on the doublesided comb structure,and realizes beam scanning from-56° to +25° in the working frequency band of 11.6?16.5GHz.The full-space beam scanning range can cover 162°,and the frequency band utilization rate is about 32.4°/GHz,and during the beam scanning process,the peak gain fluctuations are all lower than 3d B,which ensures the gain consistency during the frequency scanning process.2.Based on the composite left and right hand(CRLH)structure,a wide-angle scanning leaky wave antenna that works in the E-band is designed.A periodic mushroom-shaped unit cell is introduced into the substrate integrated waveguide(SIW)to realize the left-handed transmission characteristics,forming a composite left-handed leaky wave antenna.The antenna realizes continuous beam scanning from-58° to +16° in the frequency range of60?90GHz,and the maximum peak gain can be up to 14.84 d Bi.In the broadside direction,the H-plane 3d B beam width is 125°.The antenna has a simple structure and has the advantages of high gain and wide-angle scanning.3.Based on the spoof surface plasmon structure,a wide-angle beam scanning leaky wave antenna is designed based on the substrate integrated waveguide.The periodic slots with SSPP characteristics are etched in the substrate integrated waveguide(SIW)to further broaden the beam scanning range and realize wide-angle frequency scanning.And the asymmetrical structure is designed to suppress the open stop band(OSB)effect,so that the antenna can achieve continuous scanning from back to front.The result shows that the antenna can achieve beam scanning coverage of-72?+70 in the half-space within the operating frequency range of 68?89GHz.At the same time,due to the symmetrical dualbeam radiation characteristics of the antenna,the antenna can achieve a frequency beam scan of 284° in the entire space area.4.To improve the band utilization of the frequency scanning antenna,a narrow-band wide-angle scanning leaky wave antenna is designed by adopting a serpentine-shaped bent substrate integrated waveguide structure.Based on the substrate integrated waveguide(SIW)technology,the vertical slot on the broad side of the waveguide is used as the basic radiating unit,combined with impedance matching technology,forming a serpentine bent SIW slot array antenna.The antenna can achieve continuous beam scanning from-62° to +53° in the operating bandwidth of 72?80GHz(10.5%).During the beam scanning process,the peak gain change is less than 1.19 d B,and the maximum peak gain can reach 10.48 d Bi.The antenna has a simple structure and a low profile,which can not only achieve narrow-band wide-angle frequency scanning beam coverage,but also maintain a stable gain during the scanning process.It has a good application prospect in the field of E-band radar detection. |
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