Keep old way of inserting antenna along with new API method.

user_models/antenna_like_GSSI_1500_fs.in

@@ -0,0 +1,11 @@
+#title: GSSI 1.5GHz 'like' antenna in free-space
+#domain: 0.250 0.188 0.220
+#dx_dy_dz: 0.001 0.001 0.001
+#time_window: 6e-9
+
+#python:
+from user_libs.antennas.GSSI import antenna_like_GSSI_1500
+gssi_objects = antenna_like_GSSI_1500(0.125, 0.094, 0.100, resolution=0.001)
+for obj in gssi_objects:
+    print(obj)
+#end_python: