Abstract-This paper introduces a novel design of Butler matrix in substrate integrated waveguide (SIW) technology with wide frequency band characteristics. Butler matrices are particularly useful in advanced antenna design and characteristics such as wideband operation, power handling, manufacturing, integration, cost, etc. are typical issues to be addressed in many applications. The proposed planar 4 × 4 Butler matrix provides an interesting solution to most of these issues. Wideband operation is achieved thanks to improved cross-couplers. These components are also characterized by higher power handling when compared to E-plane couplers. The use of SIW technology enables to reduce insertion losses compared to other printed technologies, while maintaining most advantages of such technologies such as high integration, manufacturing simplicity, low weight, etc. The proposed design is fully described, from the elementary building blocks to the full assembly performances. The design is optimized for operation in Ku-band with a center frequency at 12.5 GHz. A prototype of the 4 × 4 Butler matrix is manufactured, and good performances are confirmed over 24% relative frequency bandwidth. Potential use of this sub-system in multibeam antenna design is also discussed.

This work presents an approach for the design of a quad-band substrate integrated waveguide (SIW) bandpass filter based on multilayer process. TE 101 /TE 102 /TE 103 /TE 104 modes are used to characterize the four passbands, respectively. Firstly, the locations and band ratios of the passbands are chosen based on the effective width-length of the SIW resonator and its ratio. Then, vertical couplings of the modes and source-load are designed on the middle metal layers between the dielectric layers, which provides a relatively independent bandwidth tuning and high selectivity. To demonstrate the proposed design method, a quad-band SIW bandpass filter is fabricated and measured. Experimental results agree well with the simulated counterpart. The proposed quad-band SIW filter presents good selectivity and compact size.