Research Of Rotman Lens Multibeam Antennas Based On SISL Platform

The multi-beam antennas have the advantages of higher gain and wider beam coverage,which solves the contradiction between these two important indicators in fixedbeam antennas.And the multi-beam antennas have been widely used in satellite communications,space exploration,radar systems,mobile communications,and so on.The Rotman lens is widely used as a beam-forming network(BFN)for multi-beam antennas due to its advantages such as wide operating frequency band and true time delay(TTD).At present,the designs of Rotman lens-fed multibeam antennas have been widely implemented based on transmission line structures such as metal parallel plate,rectangular waveguide,microstrip,and substrate integrated waveguide(SIW),etc.This dissertation will design Rotman lens-fed multibeam millimeter antennas based on substrate integrated suspended line(SISL)platform,with the advantages of low loss,low cost,and self-packaging.The main research contents and contributions are summarized as follows:1.Research on Rotman lens multibeam antennas based on SISL platform for low cost: In order to solve the problems of high processing cost and limited bandwidth of most Rotman lenses,the advantages of Rotman lenses based on the SISL platform are comprehensively analyzed,and detailed design steps and improvement methods are proposed.Specifically,based on the SISL platform,two Rotman lenses,ie.4×4and 8×8,and an end-fired quasi-Yagi antenna were designed,and then the lenses and antenna were integrated to verify the beam scanning performances of the multibeam antennas.The measured beam patterns show that the designed lens-fed antennas cover approximately ±24° and ±30° over the K band(18-26.5 GHz),respectively.2.Research on Rotman lens multibeam antennas based on SISL platform for wideangle scanning: In response to problems such as the degradation of the feed quality of the edge input port caused by the wider scanning range and the increase of the circuit size caused by more ports,some tradeoff design considerations have been led to the Rotman lens.Specifically,A broadband high-gain patch antenna is designed as side-fire antenna element,and a 16×16 Rotman lens is used as the BFN using SISL technology.The measurement results demonstrate that the lens-fed multibeam antenna achieves a scanning range of ±52° at 24 GHz.3.Research on miniaturized Rotman lens multibeam antennas based on SISL platform: In view of the large size of the Rotman lens multi-beam antenna,a new miniaturization method is proposed: the upper and lower air cavities of the SISL platform are loaded with high dielectric materials.And the problems of how to fix the dielectric materials and impedance matching of different equivalent dielectric constant parts are solved.According to this method,a miniaturized high permittivity dielectric filled SISL Rotman lens multibeam antenna is designed.The comparison with the above design proves that the size is reduced to 28.23% while maintaining good performance.The proposed method reduces the antenna size and also provides a new degree of freedom for the SISL Rotman lens design.