阻抗匹配禁区

A-Lin

阻抗匹配禁区
$ E  [4 E6 e$ R7 V( o

Forbidden Regions of Impedance Matching（Translate BY Lawrence）

阻抗匹配禁区

        Because of the way in which the addition of series and parallel capacitances and inductances move along lines of admittance and reactance, there are certain areas on the Smith Chart, known as forbidden regions, within the combinations of inductance and capacitance cannot be used to translate the impedance to the center of the chart (peRForm an impedance match). The reason can be made clear by an example.

       虽然通过串联或并联电容、电感的方法可以是传输线的容差和电抗发生改变，但是史密斯圆图有些特定的禁区，在禁区中，无论怎样将电容、电感如何加入都不能使阻抗匹配到圆图中心（阻抗匹配）。其中的原因从下面的例子我们就可以知道了！

                        

       Series-added reactive components (inductors and capacitors) move the impedance point along constant resistance lines as shown in red and purple to the right. Shunt-added reactive components move the impedance point along the constant conductance lines as shown in blue and green to the left. Recall that adding a shunt capacitor increases overall capacitance, and adding a series capacitor decreases the overall capacitance. The opposite is true for inductance.

       增加串联电抗元件（电感或电容）使阻抗点沿红色和紫色方向的电阻常数向右移动；增加并联电抗元件使阻抗点沿蓝色和绿色的电导常数向左移动。我们知道，并联电容会增加整体的电容值，如果串联电容会降低整体的电容值；对于电感来说正好相反。

       Suppose the impedance of a source lies in the Forbidden Region in the Smith Chart in the upper right (above). Adding series inductor increases the overall inductance and therefore moves the point along the red line (constant resistance), which keeps the impedance within the Forbidden Region. The addition of a shunt capacitor increases the overall capacitance and moves the point along the green line (constant conductance), but can never move the point to the center where 50 W lies.

  假如阻抗点位于上图中右面的史密斯圆图的匹配禁区。串联电感增加了整体的电感量，因此阻抗点会保持沿红线（阻抗常数）在匹配禁区中移动；并联电容会增加整体的电容量，使阻抗点沿绿线（电导常数）移动，但都阻抗点都不会移动到中心的50欧姆匹配点的。

                        

cat12620

感谢分享