| 摘要 |
<p>A directional coupler to be inserted into a line for transmitting wide band signals. The line has a central conductor and a grounded outer conductor. The coupler has an input terminal and an output terminal to be electrically connected to the central conductor of the line. A first series transformer has a primary winding and a secondary winding, with one side of the primary winding connected to the output terminal of the coupler. A second shunt transformer has a single winding connected between the other side of the primary winding and ground. The single winding has a first intermediate tap connected to the input terminal of the coupler and a second intermediate tap connected to an output tap point. The secondary winding of the first transformer is connected between the output tap point and ground. Sample signals applied to the output tap point by each transformer are in phase when the transformers are energized by wide band signals travelling along the line in a direction from the input terminal toward the output terminal of the coupler and are out of phase when energized by reflected signals travelling in the opposite direction. This invention increases the usable length of CATV transmission line without increasing the output level of the line amplifier. It provides a directional coupler having a relatively low tap value coupled with improved input to output impedance matching; low insertion loss; good directivity and good frequency response.</p> |
