| 摘要 |
<p>The invention relates to a implementation way of a directional coupler used in radio frequency circuits. Coupling to the transmission path of the signal to be measured takes place at one point through a measuring line (421, 422). The terminal resistor (425) of the measuring line is placed preferably in the direction of the transmission path in the field (EMF) of the signal to be measured so that it functions as part of the measuring strobe sensing the field strength. In addition, the strobe has a piece of conductor surface (424), which belongs to one conductor of the measuring line and is located on the side where the signal to be measured is coming, with respect to the resistor. The directivity is based on such an asymmetric structure of the strobe. As viewed from the transmission path, the outer end of the measuring line functions as the measuring port (P3) of the directional coupler thus formed. A good directivity is achieved on a very wide frequency range. In addition, the level of the measuring signal in relation to the level of the signal to be measured is relatively constant, and the reflection attenuation of the input port of the directional coupler is high on a wide frequency range. The directional coupler is small-sized, and it can be implemented in connection with some other structural part.</p> |
