Design of polarization conversion metasurface for RCS reduction and gain improvement of patch antenna for Ku-band radar sensing applications

•Metasurface is used to convert, as physical sensing approach, electromagnetic signals.•Achieved gain improvement for antenna sensor in Ku-band.•Radar cross section is reduced thanks to the new approach in designing and subsequent testing.•Antenna sensor based on Ku-band radar properties for sensing applications. [Display omitted] In this paper, an improved loading approach of polarisation conversion metasurface (PCM) incorporated with linearly polarised patch antenna operating in Ku band is proposed for broadband RCS reduction and gain enhancement. The proposed PCM is arranged in a checkerboard configuration based on an improved loading approach consisting of a pair of E-shaped elements placed around the radiating patch. The proposed antenna design consists of two substrates with three layers. Simulated and measured results depict that the PCM-loaded antenna has a wide impedance bandwidth of 13.8–15.2 GHz in Ku-band. The peak gain of the proposed antenna improves by 1.25 dB as compared to the reference antenna. The PCM-loaded proposed antenna shows an average RCS reduction of more than 19 dB in the wide frequency range of 9–24 GHz when compared with the RCS of reference antenna. Further, maximum RCS reduction achieved by the proposed antenna is 41.5 dB at 18.6 GHz. The proposed metasurface-loaded antenna exhibits significant RCS reduction in a wide range and also shows improvement in radiation characteristics. The proposed antenna structure is a suitable candidate for Ku-band sensing radar systems and defense applications.