Experimental investigation of a new butler matrix using slotline technology for beamforming antenna arrays

The design and realisation of a 4 times 4 Butler matrix for multibeam antenna arrays operating at 5.8timesGHz are described. The matrix is implemented on a single layer slotline structure to avoid using air bridges as required in coplanar waveguide technology. In this design, a new hybrid coupler and a crossover using slotline technology were designed and fabricated, and they are used to build a new Butler matrix. To examine the performances of the proposed matrix, numerical simulations and experimental measurements were carried out; the comparison between simulated and experimental results shows a good agreement.