120 Komal Dhiman, Deepak Sood, Krishan Gopal International Journal of Electronics, Electrical and Computational System IJEECS ISSN 2348-117X Volume 7, Issue 3 March 2018 Compact Ultrathin Polarization Rotator based on Frequency Selective Surface Komal Dhiman Dept. of Electronics and Communication Engineering, University Institute of Engineering and Technology, Kurukshetra University, Kurukshetra, India, Deepak Sood Dept. of Electronics and Communication Engineering, University Institute of Engineering and Technology, Kurukshetra University, Kurukshetra, India, Krishan Gopal Dept. of Electronics and Communication Engineering, University Institute of Engineering and Technology, Kurukshetra University, Kurukshetra, India, ABSTRACT-A novel design of frequency selective surface based polarization rotator is presented.The proposed structure rotates the linearly polarized incident wave by 90° in a given frequency band. The periodic element of the FSS is designed with a metallic pattern on the top surface and a continuous metallic layer at the bottom surface with dielectric substrate separating the two. The design exhibits -10dB bandwidth of 19% (5.7 – 6.8 GHz). The proposed structure is ultrathin with a thickness of 0.03λand have compact unit cell size 0.156λ as compared to the already reported polarization rotator.The proposed polarization rotator design has potential applications in the polarization control, in radomes, remote sensors and radiometer etc. KEYWORDS-Polarization, frequency selective surface (FSS), polarization rotation . INTRODUCTION Polarization is property of electromagnetic (EM) wave in which the direction and magnitude of the electric field vibrating in specified way. Light may be polarized by reflection or by transmission through the crystal. Polarization of the EM wave divided into linear polarization, circular polarization and elliptical polarization which have many applications. The controlling of the polarization state of EM wave is very necessary due to their many application in biological science,liquid crystal data storage, optical data storage, and in a polarimetry[1,2,3]and the controlling of the polarization state of the EM wave is FSS application such as polarization rotator[4]. In the past decade, FSS can also be used for manipulation of the polarization state of EM wave. FSS has attracted a great interest due to their many application in EM wave which are unattainable in natural material. The birefringent effect and optical activity of natural materials are widely used in a polarization control and these conventional methods of controlling polarization control are limited due to their bulky volume[5]. FSS is periodic array which consist of a metallic patches printed or slots etched on the top and bottom layer of the dielectric substrate. FSS has many advantages such as perfect absorber [8], EM cloaking [9], negative reflection[6], in phase refraction[7]. Polarization rotators are divided into two typereflection type[10] and transmission type[11] polarization rotator.Reflection type polarization rotator used in a reflect array antenna and transmission type use in a transmit array antenna. Many rotators have been developed for reflection type polarization rotator, in this rotators the bandwidth, unit cell size and thickness are main issue to improvement. There are two way to broaden the bandwidth one method is stacking metallic dielectric multilayer and other method is high impedance surface and the operating frequency band broaden by multiple plasmon resonances. In conventional polarization rotator, multilayer designs show broad bandwidth but these rotators have been