Microwave beamforming networks employing Rotman lenses and cascaded Butler matrices for automotive communications beam scanning electronically steered arrays

This paper presents the novel designs of steerable microwave beamforming networks (BFNs) employing a 4×4 Rotman Lens for operation at 3.15 GHz (S-band), an 8×8 Rotman Lens for operation at 6.3 GHz (C-band), and cascaded 4×4 Buter Matrcies for operation at 3.15 GHz (S-band). The microwave beamforming networks are intended for automotive communications beam scanning electronically steered arrays. Although the frequency range likely to be allocated to such systems is 63 GHz, where the short transmission range allows multiple frequency re-use, the planar beamforming networks are frequency scaled models to verify the concept. The objective of this investigation is to develop microwave beamforming networks suitable for a use in inter-vehicle (IVC) and roadside-to-vehicle (RVC) automotive communications electronically steered arrays. The steerable microwave beamforming networks demonstrate appropriateness to develop well-established designs for systems that can be used in automotive communications beam scanning electronically steered array and vehicular telematics.