diff --git a/DSNRxR/LNA/doc/calc_match.m b/DSNRxR/LNA/doc/calc_match.m
new file mode 100644
index 0000000000000000000000000000000000000000..b5ad33dd824412f7c45ce0e679090dc4fd47f2ab
--- /dev/null
+++ b/DSNRxR/LNA/doc/calc_match.m
@@ -0,0 +1,14 @@
+Znf = 35.4+i*48.7;
+
+Z0 = 50;
+
+Gamnfin = (Z0-Znf)/(Z0+Znf);
+
+S11 = 0.15 + i*0.56;
+S21 = 2 + i*4.1;
+S12 = 0.09 + i*0.04;
+S22 = -0.12 + i*0.37;
+
+Gamnfout = (S22 + (S21*Gamnfin*S12)/(1-S11-Gamnfin));
+
+Zout = -50*((Gamnfout-1)/(Gamnfout+1));