Substrate integrated waveguide (SIW) 3 dB coupler for K-Band applications Nurehansafwanah Khalid, Siti Zuraidah Ibrahim, Fwen Hoon Wee and Farah Shazuani Mahmud EPJ Web Conf., 162 (2017) 01078 Published online: 22 November 2017 DOI: 10.1051/epjconf/201716201078