Abstract—Our study concerns the analysis of K-band passive devices using a new technology, substrate integrated waveguide (SIW), by the HFSS code. This technology has been applied successfully to the conception of planar compact components for the microwave and millimeter waves applications. This application focuses on three components: A coupler junction (-3dB) used for routing, dividing and combining the signals in the microwave system. The levels of reflection and isolation below -15dB occupy more than 26.43% of the bandwidth, the insertion loss S 21 and coupling S 31 fluctuate between -3.24dB and -3.78dB, respectively. The SIW ferrite junction circulator has potential applications in integrated communication and radar systems. Its frequency response shows reflection losses below -15 dB in more than 21.75% of the bandwidth, an insertion loss about -0.65 dB, while the maximum of the isolation is -38.11dB. The T-junction SIW power divider (-3dB) indicates that levels of reflection below -15dB occupy more than 26.32% of the bandwidth. The transmission coefficients S 21 and S 31 are around -3.54dB, showing equal division of the power injected into port 1. In this paper, design considerations and results are discussed and presented. Index Terms—Rectangular wave guide, substrate integrated waveguide, HFSS, coupler, circulator, power divider. I. INTRODUCTION The rectangular waveguide is known for its characteristic properties of low loss and high power handling. However, due to its bulky structure, it is difficult to integrate and to manufacture at low cost in the planar structure. Recently, a new technology, called "substrate integrated waveguide (SIW)" [1], [2] has emerged. It responds to these constraints in the design of microwave components [3], integrating the rectangular waveguide in the microstrip substrate. The SIW technology is one of the most popular and developed until now because it is very easy to integrate the conventional rectangular waveguide in the standard printed circuit board (PCB). The rectangular waveguide, synthesized in the substrate integrated waveguide technology (RSIW) (Fig. 1), is built in a dielectric substrate by placing two discrete metal walls designed by metal rods, the ground plane of the substrate and the cover are also metal, preserving most of the benefits of conventional metallic rectangular waveguides. Indeed the geometry and the distribution of the electric field in (RSIW), illustrated in Fig. 2 and Fig. 3, are similar to those of the equivalent rectangular waveguide [4], [5]. In this paper, K-band RSIW components are proposed and optimized. They are building blocks of many microwave and millimeter waves integrated circuits and telecommunication systems. Manuscript received July 25, 2013; revised October 14, 2013. Bouchra Rahali and Mohammed Fehamare are with STIC Laboratory, University of Tlemcen, Tlemcen, Algeria (e-mail: b_rahali@hotmail.fr, m_feham@mail.univ-tlemcen.dz). II. DESIGN OF RSIW The concept of integrated rectangular waveguide substrate is based on electrical side walls synthesized by rows of metalized holes. The substrate of permittivity   is sandwiched between two metal plates placed on top and bottom to allow propagation of all modes TE n0 [5]. If the RSIW is properly designed by optimal parameters (Fig. 1), a width   , a diameter d of the holes, and a spacing p between two consecutive holes, its electrical behavior is similar to that of a conventional rectangular waveguide filled with the same dielectric of width   [4]. Indeed, the current lines along the side walls of the RSIW are vertical, the fundamental mode TE 10 can propagate efficiently. This means that the propagation modes, the characteristic impedances and the dispersion characteristics are almost identical with negligible radiation losses. Fig. 1. Rectangular waveguide integrated into a substrate RSIW. Based on the work of [3], empirical equations were derived:          (1)                 where   is the space wavelength. In this paper, the software HFSS [6], based on the finite element method (FEM), has been applied to analyze the RSIW devices. It should be noted that the formulas given by equations (1), (2) and (3) are commonly used to obtain initial values of  , which is optimized later by HFSS. Following this approach, we deduce the parameters (Table I) of the RSIW, designed in K-band [18-26.5] GHz from a conventional waveguide WR42 [7] (Fig. 2) Then we analyze this structure by using HFSS, which allows the electromagnetic field cartography of the TE 10 mode and the scatter diagram. Fig. 3 shows the similarity of the electric field distribution of the TE 10 mode guided in the RSIW and in its equivalent waveguide. Design of K-Band Substrate Integrated Waveguide Coupler, Circulator and Power Divider Bouchra Rahali and Mohammed Feham International Journal of Information and Electronics Engineering, Vol. 4, No. 1, January 2014 47 DOI: 10.7763/IJIEE.2014.V4.406 (2) (3)