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In this article, a multilayered substrate integrated waveguide (SIW) Butler matrix beam-forming network is proposed, designed, and demonstrated at 24 GHz for automotive radar system applications. The proposed low-cost SIW structure can be used to develop a highly integrated multibeam antenna platform in automotive radar systems and other applications. In this structure, an SIW H-plane coupler is optimized with an H-plane slit to provide the required phase shift. A class of SIW E-plane 3-dB couplers in doubled layer substrate are studied and designed as the fundamental building blocks to avoid crossovers usually required in the construction of a Butler matrix. A 4 × 4 matrix is investigated and designed, which shows excellent performance over 22-26 GHz frequency band. Two types of antenna are tested with the proposed matrix scheme. First, an antipodal linearly tapered slot antenna (ALTSA) is incorporated into the Butler matrix to verify the broadband performances. Second, a longitudinal slotted waveguide antenna array is examined to generate radiation patterns in the broadside direction. Measured results agree well with simulated counterparts, thus validating the proposed multilayer SIW design concepts. In the next sections, the use as feeding networks for providing the reconfigurability operation of an antenna will be illustrated. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2012. [ABSTRACT FROM AUTHOR]

In this work, a single coupled cavity has presented for millimeter‐wave applications. The cavity is modeled to study the effect on the quality factor by adding cylindrical posts to coupled cavity resonator. This cavity model demonstrates a higher quality factor result and better performance compare to empty substrate integrated waveguide (ESIW) filter. The concept of enhancing the quality factor by adding posts is achieved. Based on this concept, the coupled cavity and bandpass filter are presented to show the feasibility of the fabrication process for building an ESIW filter where cylindrical posts is placed in middle on the planar substrate. The introduced cavity offers very good performance around (1%) fractal bandwidth at 24.7 GHz center frequency with Q‐factor of 2236. A cavity prototype is fabricated and measured where measurements agree well with simulation. [ABSTRACT FROM AUTHOR]