Compact Multibeam Antenna Using Miniaturized Slow-Wave Substrate-Integrated Waveguide Rotman Lens for Satellite-Assisted Internet of Vehicles.

A compact multibeam antenna using a miniaturized slow wave substrate integrated waveguide (SW-SIW) Rotman lens for satellite-assisted Internet of Vehicles (IoVs) is reported in this paper. It is well known that conventional Rotman lens is bulky as the key part of the beamformer, i.e., the lens body, occupies most area of the multibeam antenna. In this work, the miniaturization of the Rotman lens body is realized first by loading slow wave structures in the form of metallized blind via-holes inside the lens. In this manner, the effective permittivity of the substrate integrated waveguide (SIW) increases. Meanwhile, the phase velocity within the Rotman lens decreases such that the guided wavelength is shortened. Consequently, the size of the SW-SIW based Rotman lens is significantly miniaturized. Compared to the conventional SIW based Rotman lens, the size of the reported lens is reduced by 66.1% with good transmission performance from 15.3 to 16.3 GHz. Moreover, the miniaturized SW-SIW Rotman lens is adopted to design a compact five-beam antenna, which was simulated, fabricated and measured. The measured results agree reasonably well with the simulations, showing the reported SW-SIW Rotman lens is an ideal candidate for Ku band satellite-assisted IoV applications.