diff --git a/user_models/sub-gridding/subgrid_basic.py b/user_models/sub-gridding/subgrid_basic.py
new file mode 100644
index 00000000..37fb2c22
--- /dev/null
+++ b/user_models/sub-gridding/subgrid_basic.py
@@ -0,0 +1,94 @@
+# Copyright (C) 2015-2020, John Hartley
+#
+# This module is licensed under the Creative Commons Attribution-ShareAlike 4.0 International License.
+# To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/4.0/.
+
+from pathlib import Path
+import sys
+import gprMax
+from user_libs.antennas.GSSI import antenna_like_GSSI_400
+
+import numpy as np
+
+# file path step
+fn = Path(__file__)
+parts = fn.parts
+
+# subgrid Discretisation is 1 mm in x, y, z directions. This allows us
+# to model the geometry of the antenna
+dl_s = 1e-3
+# subgridding ratio. This must always be an odd integer multiple. In this case
+# the main grid discrestisation is 9e-3 m.
+ratio = 5
+dl = dl_s * ratio
+
+# cells
+# default number of pml cells
+pml_cells = 10
+# distance between model and pml cells
+pml_gap = 15
+# number of cells between the Inner Surface and the Outer Surface of the sub-grid
+is_os_gap = 4
+# size of the sub-gridded region
+sub_gridded_region = 3
+# domain size
+extent = sub_gridded_region + 2 * (pml_cells + pml_gap + is_os_gap)
+
+# domain extent
+x = dl * extent
+y = x
+z = x
+
+tw = 1e-9
+
+scene = gprMax.Scene()
+
+title_gpr = gprMax.Title(name=fn.name)
+dxdydz = gprMax.Discretisation(p1=(dl, dl, dl))
+domain = gprMax.Domain(p1=(x, y, z))
+time_window = gprMax.TimeWindow(time=tw)
+
+scene.add(domain)
+scene.add(title_gpr)
+scene.add(dxdydz)
+scene.add(time_window)
+
+sg_x0 = (pml_cells + pml_gap + is_os_gap) * dl
+sg_y0 = sg_x0
+sg_z0 = sg_x0
+
+sg_x1 = sg_x0 + sub_gridded_region * dl
+sg_y1 = sg_x1
+sg_z1 = sg_x1
+
+sg_p0 = [sg_x0, sg_y0, sg_z0]
+sg_p1 = [sg_x1, sg_y1, sg_z1]
+
+sg = gprMax.SubGridHSG(p1=sg_p0, p2=sg_p1, ratio=ratio, id='mysubgrid')
+scene.add(sg)
+
+# plastic box in sub grid
+material = gprMax.Material(er=3, mr=1, se=0, sm=0, id='plastic')
+scene.add(material)
+plastic_box = gprMax.Box(p1=(30*dl, 30*dl, 30*dl), p2=(31*dl, 31*dl, 31*dl), material_id='plastic')
+sg.add(plastic_box)
+
+# create a geometry view of the main grid and the sub grid stitched together
+gv = gprMax.GeometryView(p1=(0, 0, 0),
+                         p2=domain.props.p1,
+                         dl=dl,
+                         filename=fn.with_suffix('').parts[-1],
+                         output_type='f',
+                         multi_grid=True)
+
+
+# create a geometry view of the main grid and the sub grid stitched together
+gv_normal = gprMax.GeometryView(p1=(0, 0, 0),
+                         p2=domain.props.p1,
+                         dl=dl,
+                         filename=fn.with_suffix('').parts[-1] + '_voxels',
+                         output_type='n')
+scene.add(gv)
+#scene.add(gv_normal)
+
+gprMax.run(scenes=[scene], n=1, geometry_only=False, outputfile=fn, subgrid=True, autotranslate=True)