| abstract |
A directional coupler characterized as having improved directivity. The directional coupler and methodology uses enhanced destructive interference to reduce the leakage at the output port of a signal incident at the coupled port of the coupler thereby giving the coupler improved directivity. The directional coupler creates this enhanced destructive interference by the introduction of impedance discontinuities in the coupled transmission lines. The impedance discontinuity in the coupled transmission lines can take on many forms, such as recesses at the coupling sides of the coupled transmission lines, protrusions at the non-coupling sides of the coupled transmission lines, or both. Another directional coupler is capable of being tuned for different coupling levels. This coupler comprises adjacent conductors between the coupled transmission lines that are connected, as required, to the coupled lines to change the coupling level. |