Wide-Scanning Conformal Phased Array Antenna for UAV Radar Based on Polyimide Film

Polyimide film is a practicable alternative to the conventional substrates utilized in conformal antennas. Due to its flexibility, the antennas based on the polyimide film can be easily conformed to the platform surface. An eight-element linear-phased array operating at the P-band with a wide scan angle is investigated in this letter, which is constructed by the dipoles printed on the polyimide film. The antenna surface is mounted on the front wing of an unmanned aerial vehicle (UAV). Strong coupling is observed between the array elements when the beam scans. Therefore, decoupling structures are loaded in the array elements to broaden the scan angle. To satisfy the requirement of the radar system, directors and reflectors are also employed on the surface of the front wing to narrow the main lobe beamwidth in the elevation plane. The proposed phased array achieves a fractional bandwidth of 16.7% when scanning up to ±60° in the E-plane. The validity of this design is verified by the simulation and measurements of a 1 × 8 array prototype.