Alow-cost, compact 8 Ã?â?? 8 Butler matrix based on a novel bilayer microstrip configuration is presented and implemented for 4.3GHz\ntelecommunication application. A back-to-back placed bilayer microstrip structure has been proposed to avoid using crossover. To\nexpand operational bandwidth of the Butler matrix, a three-branch line directional coupler has been employed as 3 dB/90Ã?° bridge,\nand a kind of improved two-order Schiffman phase shifter has been adopted as fixed phase shifter. For application of indoor wireless\ncommunication, a compact broadband 8 Ã?â?? 8 Butler matrix has been designed and fabricated. The measured results show that the\nreturn loss of the matrix is lower than -10 dB, the isolation is better than 17 dB, the power distribution error is less than Ã?±2.0 dB,\nthe phase error is less than Ã?±15Ã?°, and the relative bandwidth is more than 23%.
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