How to scale vectors in VectorPlot?

Question

I generated some pics from 2 datum，one in $x$ direction and the other in $y$，so I used the commands:

exfield = Range[200];
polarplane = Range[200];
Get["C:\\Users\\dc\\Desktop\\polarplane.dat"];
Get["C:\\Users\\dc\\Desktop\\exfield.dat"];
xx = Table[
Transpose[{exfield[[25, i]], polarplane[[25, i]]}], {i, 71}];
ListVectorPlot[xx]

to get the vector field. But one problem here is, all the pics generated by the commands share the same maximum length of the vector. I can only see the orientation change but no magnitude change. I need a cartain standard (for instance, 1 cm vector length for the maximum data value $a_{max}$) to generate all the pics, so I can see the relative magnitude change. But I couldn't find the options. Have anyone encountered this same problem? Thank you. And the sample datum are like:

 exfield[[001]] = {              
{
   a11,
   ……，
   a1i，
},
{
   a21,
   ……，
   a2i，
 },
   ……
 {
   ai1,
   ……，
   aii，
  },
 }

and the sample data:

data

Answer 1

You can use the VectorScale option for ListVectorPlot to control the scaling of vector sizes.

ListVectorPlot[Table[{y, -x}, {x, -3, 3, 0.2}, {y, -3, 3, 0.2}], 
 VectorScale -> .05]

ListVectorPlot[Table[{y, -x}, {x, -3, 3, 0.2}, {y, -3, 3, 0.2}], 
 VectorScale -> .1]

Here is a fleshed out version:

Gather some data:

xxs = Table[Transpose[{exfield[[#, i]], polarplane[[#, i]]}], {i, 71}] & /@Range[27,35];

Find the relevant max vector sizes.

scales = With[{s = Max@Apply[Norm@#&,#,{2}] & /@ xxs}, s/Max@s];

Plot the vector fields, with a couple of fiddle factors for arrowhead size and absolute vector length:

GraphicsGrid[
 Partition[
  MapThread[
   ListVectorPlot[#1, VectorScale -> #2, 
     VectorStyle -> Arrowheads[#2 0.015]] &, {xxs, 0.3 scales}], 3]]