60 GHz Investigation of Building Scattering at 2 GHz
Using a Scale Model
Jonathan S. Lu and Henry L. Bertoni
Electrical and Computer Engineering Department
Polytechnic Institute of New York University
firstname.lastname@example.org and email@example.com
Patrick Cabrol and Daniel Steinbach
InterDigital Communications, LLC
Abstract—In this work, we investigate building scattering at 2
GHz by performing 60 GHz scattering measurements on a 1/30
scale building model. The materials used to build this model were
chosen to have similar reflected and transmitted power
characteristics at 60 GHz that are common to building materials
at 2 GHz. Co-polarized and cross-polarized scattering
measurements of the model were performed with and without
furniture and the front building surface. Near the specular
direction, results show that the contribution from waves that
enter a building, internally scatter and/or reflect, and then exit
the building are not significant compared to those that only
interact with the features on the front building surface. However,
away from the specular direction, the influence of this
contribution can be observed.
Index Terms— Buildings, millimeter wave, mmW, Scaled
Measurements, Scattering, UHF
Understanding and modeling the scattering from buildings
at the sub-GHz and GHz frequencies has been a subject of
interest for radio systems in urban environment , . Along
with affecting the total power, this multipath significantly
affects the angle of arrival and departure profiles of a radio
link, which are especially important for MIMO links.
Past research  has shown that scattering from features on
a building surface such as columns and balconies, can give a
significant contribution to the total building scattered signal. It
is unclear whether the contributions from waves that enter a
building, scatter and then exit the building will also have a
significant impact on the total scattered signal. Furthermore,
the impact of furniture inside the building is also unknown.
Figure 1. 1/30 scale model and measurement setup.
The purpose of this study is to investigate the impact of
furniture and building surfaces on the scattered signal at 2
GHz. We use a scale model approach similar to that of  and
. Measurements were made at 60 GHz on a 1/30 scale model
for cases with and without office furniture and/or front building
surface. From these measurements, we are able to gain a
qualitative understanding of the impact of different building
features on the total scattered signal.
II. MEASUREMENT OVERVIEW
Scattering measurements on a scale model were made using
an indoor testbed. From these measurements, we compute the
scattering gain defined as the received scattered power
normalized to the free-space received power over the scattered
A. 1/30 Scale Model
The 1/30 scale model shown in Fig. 1 was used in our
scattering measurements. This model had three floors with
eight rooms and one corridor per floor as seen in Figs. 1 and 2.
Each room is 127 mm x 139.7 mm (models a 3.8 m x 4.2 m
room at 2 GHz). The interior and exterior walls, the floors, and
the ceilings were created from 6.35mm maple plywood (εr =
3.1 –j0.08). The reflectivity of this plywood at 60 GHz for a TE
wave at normal incidence was measured to be -9.4 dB which is
similar to the -8.2 dB reflectivity of 178 mm thick concrete (εr
= 6.3 –j0.69) and -6.6 dB reflectivity of 12.7mm thick drywall
(εr = 3.57 –j0.76) at 2 GHz. The transmissivities of the
materials are also expected to be similar. The removable
building surfaces, also shown in Fig. 1, are designed so that
each room has a 101.6 mm x 48.5 mm window, which models
a 3.05 m x 1.46 m window at 2 GHz.
To represent common office furniture, wooden blocks and
metal pieces 1/30
the size of typical office furniture were used
as seen in Fig. 2. The model furniture was chosen to be of
simple geometries in order to facilitate simple grid assignments
in future FDTD and ray-tracing simulations. The following
furniture were placed in each room using a mold to ensure
accurate furniture placement: 1) three metal chairs, 2) one
wooden bookcase 3) one wooden circular table, 4) one wooden
rectangular desk, and 5) two metal light fixtures.
B. Measurement Setup
The measurement test bed shown in Fig. 1 was used to
perform scattering measurements on the model. It was
composed of two 2 m arms having the same focal point. Each
arm had a horn antenna (11 degree 3 dB beamwidth) on one
end and a hinge on the other. At each hinge was an angle meter
which ensured accurate angle positioning of the incident angle
θi and scattering angle θs. The front surface of the scale model
was placed over the focal point as seen in Fig. 1. To perform
scattering measurements for a specific incident angle θi, the
transmit antenna arm was moved to the desired θi, while the
receive antenna arm was moved in an arc so that θs spanned a
desired range of angles. To perform reflection measurements,
both arms were moved so that θs= -θi. Note that because the
antennas are attached to the arms, the distances from the
antennas to the model remain constant.
As seen in Fig. 1, microwave absorbers with over 50 dB
absorption at 60 GHz were placed behind the model and in
front of the model stand to ensure that any multipath
originating from the model stand or wall behind the model was
severely attenuated. From scattering measurements taken
without the model, the scattering gain from undesired multipath
was < -55 dB. The scattering gain noise floor in our
measurements was approximately -80 dB.
III. RESULTS AND ANALYSIS
The average scattering gain for an incident wave of θi = -10
degrees is shown in Fig. 3. The average scattering gain is found
from varying θs from 4 to 80 degrees. Measurements are taken
at increments of 2 degrees. This process is repeated after
shifting the model vertically ½ floor and horizontally ½ room.
The average scattering gain is then computed by averaging the
three scattering gain measurements. This procedure was
repeated for incident angles of -45 and -70 degrees.
The scattering gain curves when only the building surface is
present (solid line in Fig. 3), and with building surface, floors,
walls and furniture (dotted line with squares in Fig. 3) are
similar. However when the building surface is removed from
the complete model (solid line with circles in Fig. 3), there is a
5 dB difference. The total scattering contribution appears to be
dominated by scattering from the building surface in and near
the specular direction. For all curves in Fig. 3, the scattering is
centered at the specular direction θs = 10 degrees as found in
. This is also true for the average scattering gains found for
incident angles of -45 and -70 degrees.
When the first surface is present, furniture does not seem to
have an effect on the total signal near the specular direction.
Away from the specular direction, the presence of furniture
seems to increase the scattering gain. For θs > 20 degrees when
the front building surface is present, the scattering gain appears
to be on average a few dB greater with furniture (dotted line
with squares in Fig. 3) than without furniture (solid line with
triangles in Fig. 3). Without the front building surface present
(solid line with circles and dashed line in Fig. 3), the same
trend is seen for θs > 25 degrees.
From results not shown, the cross-polarized received signal
is over 20 dB below the co-polarized received signal in and
around the specular angle. Away from the specular angle, the
average difference is 10dB. These results are much greater than
those given in , where the measured difference for an office
building is approximately 4dB. This difference may be due to
the simple building surface of our model.
This paper presents an investigation of 2 GHz building
scattering using 60 GHz scale measurements. Measurements
show that the scattered signal near the specular direction is
dominated by scattering from the building surface. Though,
away from the specular direction, the internal layout has a
significant effect on the scattered signal.
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Figure 2. Floor plan and furniture layout.
0 10 20 30 40 50 60 70 80
Only Building Surface
With Building Surface and Furniture
With Building Surface and Without Furniture
Without Building Surface and With Furniture
Without Building Surface and Furniture
Figure 3. Average scattering gain for incident angle θi = -10