Contents I. Introduction
The considerable growth in the mm-wave systems has placed extensive research effort in developing high efficient radiators, with relatively wide bandwidth and compatibility with planar integrated circuits. In this context, DRAs are proved to be excellent candidates due to their negligible conductor losses, light weight, flexibility in their design and compatibility with various feeding mechanisms[1]. Among the various reported feeding techniques, aperture coupling is preferred in mm-wave range for ease of fabrication. Further, Substrate integrated waveguide (SIW) technology has been integrated with DRAs to provide high radiation efficiency at mm-wave band in both linear polarization (LP)[2], and circular polarization (CP)[3]. Sequential rotation is a popular technique used to enhance the radiation characteristics of circularly polarized arrays such as high polarization purity, good axial ratio[4]. In[5], a novel simplified configuration for sequential feeding circuit is introduced using the SIW technology to provide the required phase difference without a need to add extra quarter wavelength lines for achieving the required 90 ° phase shift using LP rectangular DRAs. In this paper, parasitic DRA element is added at one side of the driven DRA in each branch to enhance the performance of the driven DRA using field coupling. Simulated results of the designed structure are presented to validate the proposed antenna array design.
