阻抗圆图，或者叫史密斯图，是无线电设计方面用的；

基本的阻抗圆图如下，

下面尝试用C#能不能画一下；

先在网上找一个画坐标的C#类，它的效果如下；

自己再增加一个函数，可以绘制中心在画布中心的坐标系；

看一下基本的阻抗圆图，它有4个圆；先把4个圆画一下如下，

那几条曲线不知道怎么画，不知道是什么曲线，用什么函数描述； 有时间继续；

using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms; using System.Drawing; using System.Drawing.Drawing2D;  namespace commengineer {     public static class XYlinesFactory     {         #region   画出X轴与Y轴         /// 
           /// 在任意的panel里画一个坐标，坐标所在的四边形距离panel边50像素           /// 
           ///            public static void DrawXY(Panel pan)         {             Graphics g = pan.CreateGraphics();             //整体内缩move像素               float move = 50f;             float newX = pan.Width - move;             float newY = pan.Height - move;              //绘制X轴,               PointF px1 = new PointF(move, newY);             PointF px2 = new PointF(newX, newY);             g.DrawLine(new Pen(Brushes.Black, 2), px1, px2);             //绘制Y轴               PointF py1 = new PointF(move, move);             PointF py2 = new PointF(move, newY);              g.DrawLine(new Pen(Brushes.Black, 2), py1, py2);         }         #endregion          public static void DrawCXY(Panel pan)         {             Graphics g = pan.CreateGraphics();             //整体内缩move像素               float move = 50f;             float newX = pan.Width - move;             float newY = pan.Height - move;              float x1 = move / 2;             float x2 = move / 2 + newX;             float y1 = newY / 2 + move/2;              PointF p1 = new PointF(x1, y1);             PointF p2 = new PointF(x2, y1);             PointF p3 = new PointF(move/2 + newX/2, move/2);             PointF p4 = new PointF(move / 2 + newX / 2, pan.Height - move/2);              g.DrawLine(new Pen(Brushes.Black, 1), p1, p2);             g.DrawLine(new Pen(Brushes.Black, 1), p3, p4);         }          public static void DrawSmithCircle(Panel pan)         {             Graphics g = pan.CreateGraphics();             float bound = 50f;             float centerX = pan.Width / 2;             float centery = pan.Height / 2;             float scr1 = ((pan.Width - bound) /2) * 0.8f;              float scr2 = (scr1 + scr1 / 2) / 2;             float scr3 = scr1 / 2;             float scr4 = scr3 / 2;              //float r1 = ((pan.Width - 50f) / 2) * 0.8f;             //GraphicsPath circlePath = new GraphicsPath();             //circlePath.AddEllipse(pan.Width/2, pan.Height/2, r1, r1);              // 设置画笔和填充色             //Brush brush = Brushes.Blue;              // 绘制圆             g.DrawEllipse(new Pen(Brushes.Black, 1), centerX - scr1, centery - scr1, scr1*2, scr1*2);             g.DrawEllipse(new Pen(Brushes.Black, 1), centerX - scr1/2, centery - scr2, scr2 * 2, scr2 * 2);             g.DrawEllipse(new Pen(Brushes.Black, 1), centerX, centery - scr3, scr3 * 2, scr3 * 2);             g.DrawEllipse(new Pen(Brushes.Black, 1), centerX+scr3, centery - scr4, scr4 * 2, scr4 * 2);              //g.FillPath(brush, circlePath);         }          /// 
           /// 画出Y轴上的分值线，从零开始           /// 
           ///            ///            ///                #region   画出Y轴上的分值线，从零开始         public static void DrawYLine(Panel pan, float maxY, int len)         {             float move = 50f;             float LenX = pan.Width - 2 * move;             float LenY = pan.Height - 2 * move;             Graphics g = pan.CreateGraphics();             for (int i = 0; i <= len; i++)    //len等份Y轴               {                 PointF px1 = new PointF(move, LenY * i / len + move);                 PointF px2 = new PointF(move + 4, LenY * i / len + move);                 string sx = (maxY - maxY * i / len).ToString();                 g.DrawLine(new Pen(Brushes.Black, 2), px1, px2);                 StringFormat drawFormat = new StringFormat();                 drawFormat.Alignment = StringAlignment.Far;                 drawFormat.LineAlignment = StringAlignment.Center;                 g.DrawString(sx, new Font("宋体", 8f), Brushes.Black, new PointF(move / 1.2f, LenY * i / len + move * 1.1f), drawFormat);             }             Pen pen = new Pen(Color.Black, 1);             g.DrawString("Y轴", new Font("宋体 ", 10f), Brushes.Black, new PointF(move / 3, move / 2f));         }         #endregion          /// 
           /// 画出Y轴上的分值线，从任意值开始           /// 
           ///            ///            ///            ///            #region   画出Y轴上的分值线，从任意值开始         public static void DrawYLine(Panel pan, float minY, float maxY, int len)         {             float move = 50f;             float LenX = pan.Width - 2 * move;             float LenY = pan.Height - 2 * move;             Graphics g = pan.CreateGraphics();             for (int i = 0; i <= len; i++)    //len等份Y轴               {                 PointF px1 = new PointF(move, LenY * i / len + move);                 PointF px2 = new PointF(move + 4, LenY * i / len + move);                 string sx = (maxY - (maxY - minY) * i / len).ToString();                 g.DrawLine(new Pen(Brushes.Black, 2), px1, px2);                 StringFormat drawFormat = new StringFormat();                 drawFormat.Alignment = StringAlignment.Far;                 drawFormat.LineAlignment = StringAlignment.Center;                 g.DrawString(sx, new Font("宋体", 8f), Brushes.Black, new PointF(move / 1.2f, LenY * i / len + move * 1.1f), drawFormat);             }             Pen pen = new Pen(Color.Black, 1);             g.DrawString("Y轴", new Font("宋体 ", 10f), Brushes.Black, new PointF(move / 3, move / 2f));         }          #endregion         /// 
           /// 画出X轴上的分值线，从零开始           /// 
           ///            ///            ///            #region   画出X轴上的分值线，从零开始         public static void DrawXLine(Panel pan, float maxX, int len)         {             float move = 50f;             float LenX = pan.Width - 2 * move;             float LenY = pan.Height - 2 * move;             Graphics g = pan.CreateGraphics();             for (int i = 1; i <= len; i++)             {                 PointF py1 = new PointF(LenX * i / len + move, pan.Height - move - 4);                 PointF py2 = new PointF(LenX * i / len + move, pan.Height - move);                 string sy = (maxX * i / len).ToString();                 g.DrawLine(new Pen(Brushes.Black, 2), py1, py2);                 g.DrawString(sy, new Font("宋体", 8f), Brushes.Black, new PointF(LenX * i / len + move, pan.Height - move / 1.1f));             }             Pen pen = new Pen(Color.Black, 1);             g.DrawString("X轴", new Font("宋体 ", 10f), Brushes.Black, new PointF(pan.Width - move / 1.5f, pan.Height - move / 1.5f));         }         #endregion          #region   画出X轴上的分值线，从任意值开始         /// 
           /// 画出X轴上的分值线，从任意值开始           /// 
           ///            ///            ///            ///            public static void DrawXLine(Panel pan, float minX, float maxX, int len)         {             float move = 50f;             float LenX = pan.Width - 2 * move;             float LenY = pan.Height - 2 * move;             Graphics g = pan.CreateGraphics();             for (int i = 0; i <= len; i++)             {                 PointF py1 = new PointF(LenX * i / len + move, pan.Height - move - 4);                 PointF py2 = new PointF(LenX * i / len + move, pan.Height - move);                 string sy = ((maxX - minX) * i / len + minX).ToString();                 g.DrawLine(new Pen(Brushes.Black, 2), py1, py2);                 g.DrawString(sy, new Font("宋体", 8f), Brushes.Black, new PointF(LenX * i / len + move, pan.Height - move / 1.1f));             }             Pen pen = new Pen(Color.Black, 1);             g.DrawString("X轴", new Font("宋体 ", 10f), Brushes.Black, new PointF(pan.Width - move / 1.5f, pan.Height - move / 1.5f));         }         #endregion       } }

调用代码；

        private void toolStripMenuItem2_Click(object sender, EventArgs e)         {             //XYlinesFactory.DrawXY(panel1);             //XYlinesFactory.DrawXLine(panel1, 100.00f, 12);             //XYlinesFactory.DrawYLine(panel1, 100.00f, 12);              XYlinesFactory.DrawCXY(panel1);             XYlinesFactory.DrawSmithCircle(panel1);         }          private void Form8_Load(object sender, EventArgs e)         {             panel1.Width = 600;             panel1.Height = 600;         }

看了一点资料，这图上都是圆；曲线的那几根是圆弧，是圆的一部分；

把圆在脑子里想出来，按照C#画弧的方式，只画出圆的一部分；加上如下四句画弧的代码，

            g.DrawArc(new Pen(Brushes.Black, 1), centerX,centery-scr1*2, scr1*2,scr1*2,  90, 90);             g.DrawArc(new Pen(Brushes.Black, 1), centerX, centery, scr1 * 2, scr1 * 2, 180, 90);             g.DrawArc(new Pen(Brushes.Black, 1), centerX-scr1/2, centery-scr2*3, scr2 * 3, scr2 * 3, 90, 78);             g.DrawArc(new Pen(Brushes.Black, 1), centerX - scr1 / 2, centery, scr2 * 3, scr2 * 3, 192, 78);

效果如下，

还没完全理解它的规律；

所取的画弧的正方形的边长分别是scr1 * 2,   scr2*3，转78的角度也是大致试出来的；

scr1是最大圆的半径，scr2是第二大圆的半径；

g.DrawArc()的第一个参数是画笔，接下来2个参数是画弧参照正方形的左上角x和y坐标，再接下来2个参数是正方形的长和宽，然后是画弧的起始角度，最后一个参数是需要画多大的角度；