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60 GHz Investigation of Building Scattering at 2 GHz Using a Scale Model
Research Paper / Feb 2014

 

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 

 

lushiaoen@gmail.com and hbertoni@poly.edu  

 

Patrick Cabrol and Daniel Steinbach 

 

InterDigital Communications, LLC 

 

Patrick.Cabrol@interdigital.com and 

 

Daniel.Steinbach@interdigital.com 

 

 

 

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  

 

 

 

I. INTRODUCTION 

 

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 [1], [2]. 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 [1] 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 [3] and 

[4]. 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 

 

path length. 

 

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

 

th

 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 

[2]. 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 [2], where the measured difference for an office 

building is approximately 4dB. This difference may be due to 

the simple building surface of our model. 

 

IV. CONCLUSION 

 

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. 

 

REFERENCES 

 

[1] M.R.J.A.E. Kwakkernaat and M.H.A.J. Herben, “Diagnostic analysis of 

radio propagation in UMTS networks using high-resolution angle-of-

arrival measurements,” in IEEE Antennas and Propagation Magazine, 

Vol. 53, No. 1, pp. 66-75, Feb. 2011. 

 

[2] E. M. Vitucci, F. Mani, V. Degli-Esposti, and C. Oestges, “Polarimetric 

properties of diffuse scattering from building walls: Experimental 

parameterization of a ray-tracing model,” in IEEE Trans. Antennas and 

Propagation, Vol. 60, No. 6, pp. 2961-2969, June 2012. 

 

[3] D. Erricolo, G. D'Elia, and P.L.E. Uslenghi, “Measurements on scaled 

models of urban environments and comparisons with ray-tracing 

propagation simulation,” in  IEEE Trans. Antennas and Propagation, 

Vol. 50, No. 5, pp. 725-735, May 2002. 

 

[4] F. Aryanfar and K. Sarabandi, "Validation of Wireless Channel Models 

Using a Scaled mm-Wave Measurement System, " IEEE Antennas and 

Propagation Magazine, Vol.49, No.4, pp.124-134, Aug. 2007. 

 

 

 

 

Figure 2.  Floor plan and furniture layout.  

 

0 10 20 30 40 50 60 70 80

-55

 

-50

 

-45

 

-40

 

-35

 

-30

 

-25

 

-20

 

-15

 

-10

 

Scattered Angle 

s

  [degrees]

 

A

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ra

ge

 

 S

ca

 

tte

rin

 

G

 

ai

 

[d

B

 

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 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 

degrees.