Currently, many automotive radar systems employ linear arrays of series fed antennas whose beam steering is limited to a single plane. Circular antenna arrays offer unique beam steering advantages over linear arrays which make them desirable for adaptive beam steered radar applications. Due to their inherent symmetry, circular arrays are capable of beam steering in the elevation plane as well as 360- degrees in the azimuth plane. Two types of circular arrays are presented both with uniform magnitude excitation and non-uniform phase excitation. The first one is an 8-element conformal circular array of CPW-fed dual dipole radiating elements, designed at 2.45 GHz using HFSS, to scan a 360-degree azimuth region. This array may be placed on top of a road vehicle and used in an autonomous or semi-autonomous driving system to scan the surrounding environment for obstacles or to supplement other sensing systems such as LiDAR and computer vision in inclement weather such as fog, low-light conditions, or snow where the performance of other sensors suffer. The electronic steering of the array would eliminate the mechanical rotation of conventional and commercially available nautical radar systems. The distortion of the radiation pattern of a single dipole fed by a coplanar waveguide (CPW) is overcome with a dual dipole configuration as the radiating element. The primary challenge is the design of the feed system that starts as a corporate microstrip transmission line system and is aperture coupled with a transition to the CPW feeding the dipoles. Both the feed system and antenna elements are etched on either side of a single thin dielectric sheet which is then wrapped into a cylinder to form the circular array. The second one is a circular microstrip patch array designed at 10 GHz using HFSS to scan a narrow beam in a conical broadside region. The array may be placed on the front of a vehicle used in adaptive beam-steering applications for obstacle detection with the beam steered for two degrees of freedom, to anticipate curvature in the road to increase the effective range over a conventional radar array. Prototypes are fabricated on duroid with passive phase excitations to demonstrate beam steering. Measured radiation pattern and gain of both types of the prototypes show excellent agreement with simulated results. Speaker(s): Connor Devitt, Virtual: https://events.vtools.ieee.org/m/281835