Design Of Periodic Leaky-Wave Antenna With Continuous Beam Scanning Based On Slow-Wave Substrate Integrated Waveguide

As a class of traveling-wave antennas,the leaky wave antennas have the main beam scanning with frequency.Periodic leaky-wave antennas have the main scanning beam in the both backward and forward quadrant spaces.Therefore,periodic leaky-wave antennas have attracted much attention because of wide scanning range.However,periodic leaky-wave antennas face two problems.One is the poor radiation performance under the short length of antenna.Good radiation performance usually requires much larger apertures.The other is the broadside radiation deteriorated due to the presence of open-stopband（OSB）,which makes it impossible for periodic leaky wave antennas to achieve continuous beam scanning from backward-to-forward direction.The slow-wave substrate integrated waveguide is formed by loading the slow-wave structures on the basis of traditional substrate integrated waveguide.The slow wave structures decelerate the phase velocity of the electromagnetic wave traveling in substrate integrated waveguide by increasing the effective permeability or permittivity,reducing the guide wavelength.Compared with normal SIW periodic leaky-wave antenna with the same length,the distance between the adjacent radiating slots in the proposed SW-SIW PLWA is decreased,resulting in more radiating slots in SW-SIW PLWA,leading to increased efficiency and gain.Compact period leaky wave antennas with continuous beam scanning through broadside and good radiation performance based on the slow-wave substrate integrated waveguide transmission line with a limited length are designed.In this thesis,for the study of periodic leaky-wave antenna designed based on slow-wave substrate integrated waveguide,the following works are carried out:1.Periodic leaky-wave antenna with increased gain and continuous beam scanning is designed based on slow-wave substrate integrated waveguide.The periodic leaky wave antenna based on normal substrate integrated waveguide is designed first,which has the problems of low gain and open-stopband.In order to solve the problem of low gain with limited length of antenna,a periodic leaky wave antenna based on slow-wave substrate integrated waveguide is designed.Loading slow-wave structures can effectively reduce the guided wave wavelength of electromagnetic waves,while the period of the radiating units of the periodic leaky-wave antenna is about one guided wave wavelength,resulting in more radiating units in slow-wave substrate integrated waveguide periodic leaky wave antenna,leading to the improved gain.In order to realize continuous beam scanning through broadside,the OSB is suppressed by extending the loaded patches,with which the impedance match of cell structures is completed.Finally,the designed antenna is measured and verified.In the operating frequency range of 13.4-15.4 GHz,S₁₁ is less than-10 d B,and S₂₁ is less than-10 d B.The scanning angle of the proposed PLWA reaches 72.7°during the operating frequency range with maximum gain of 8.47 d Bi.The simulation results are in good agreement with the measured results,which verifies the feasibility of the design in this chapter.2.Periodic leaky-wave antenna with miniaturized dimensions and continuous beam scanning through broadside is designed based on slow-wave half mode substrate integrated waveguide.A slow-wave half mode substrate integrated waveguide is designed first,which effectively reduces the lateral dimension of the transmission line.Then,a compact periodic leaky-wave antenna with continuous beam scanning through broadside is designed based on the above slow wave half mode substrate integrated waveguide.The OSB is suppressed by loading the impedance matching structure based on slow wave structure.Compared with periodic leaky wave antenna based on the common slow wave substrate integrated waveguide,the lateral size of the proposed antenna is reduced to 46.4%.Finally,the designed antenna is measured and verified.In the operating frequency range of 13.7 GHz-15.7 GHz,S₁₁ is less than-10 d B,and S₂₁ is less than-10 d B.The scanning angle of the proposed PLWA reaches 62.3°during the operating frequency range with maximum gain of 11 d Bi.The simulation results are in good agreement with the measured results,which verifies the feasibility of the design in this chapter.