| 摘要 |
A directional coupler designed to operate in a predetermined frequency range which includes a first electrical conductor of predetermined length and width, a second electrical conductor having the same length as the first electrical conductor, which is narrower than the first electrical conductor and fully underlies or overlies the first conductor. A dielectric is disposed between the first and second conductors. The width of the first electrical conductor is selected to be 2 DELTA 1 wider than the second electrical conductor, where DELTA 1 is wider than the layer to layer alignment tolerance of the fabrication process being used. The length of each conductor is less than gamma /8 epsilon r+E,fra 1/2+EE , where gamma is the free space wavelength at the designed frequency of the coupler. The coupler can further include a slot disposed within the first electrical conductor for reduced coupling values. The above described coupler can be cascaded with narrow conductors coupled to wide conductors and vice versa. By cascading pairs of coupled lines with opposite orientations, the reflection coefficients are maintained nearly identical at all ports and the coupling values are the same as long as the coupled line sections meet certain dimensional limitations.
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