Study And Design Of Conformal Radial Line Slot Antennas

A radial line slot antenna(RLSA) is a nonresonant multimode waveguide slotted planar array. In the last two decades, as it holding both the advantages of free of conductor loss and high efficiency of slotted waveguide arrays, and the intrinsic low cost for mass production and planarity of microstrip arrays, high gain RLSAs have been widely used for microwave and millimeter wave systems. Lots of papers have been published on this topic. However, they all refer to a uniform field aperture distribution that produces a maximum antenna gain. The fulfillment of this requirement is sufficient for several telecommunication systems, but not for all. As a matter of fact, the design of dual-frequency antennas, monopulse antennas and conformal antenna are often requested. The effectiveness of a RLSA solution for these cases is still an open question.Based on the situation above, this thesis aims at expanding the application range of high efficiency RLSA, for which, further research on planar and quadric surface conformal RLSA are carried out after in-depth analysis of the principle and design method of conventional single layer RLSA. The main contents of this thesis are listed as follows:First of all, this thesis introduces the background, relevant research dynamic, and significance of the research, goes into details on the fundamental theory and design techniques, designs and compares some types of conventional RLSA, which lay a foundation for later studies.Then, performing some innovation on the structure and the feed of single layer RLSA, this thesis design three types of planar antenna: shared-aperture dual-band and dual-circularly polarized RLSA, capacitive pin feed spiral arranged single layer RLSA and monopulse RLSA. Simulation results show the feasibility and effectiveness of these innovation operations. A prototype of monopulse RLSA is manufactured and tested. The antenna achieves radiating sum and difference beams simultaneously, and the simulated and tested gain of sum beam are 32.51 dB and 31.10 dB respectively, good accordance is obtained between simulated and measured results, which reach to the expected target.At last, this thesis proposes a new design strategy for quadric surface conformal RLSA. After studying the distribution of waveguide dominant modal field and strictly derived the phase lag compensation for the optical path difference due to the curved surface structures, we design two types of convex quadric surface conformal RLSA, spherical and paraboloid. The simulation results show that the conformal RLSA can keep high efficiency when the ratio of the height and the aperture diameter of antenna lower than the value of 0.14, and efficiency decreases dramatically when it exceeds the value. After that, this thesis proposes a shared-aperture parabolic reflector/RLSA antenna, the feasibility and validity of the antenna is validated by of an example designed.