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Propagation Characterization of an Office Building in the 60 GHz Band
Research Paper / Feb 2014 / mmW

This work investigates the propagation characteristics of an office building in the 60 GHz band. From reflection and scattering measurements of several painted and un-painted common building materials recorded at 60 GHz, the complex permittivity and Lambert’s Law scattering coefficient of each material are extracted. Diffraction measurements at a building corner at 60 GHz are also presented and analyzed. Lastly, power angular profiles of building penetration and scattering at 60 GHz are presented and used to characterize the outdoor to indoor propagation, and the significant scatterers on a building surface, respectively.


Propagation Characterization of an Office Building in 

the 60 GHz Band 




Jonathan Lu1, Daniel Steinbach2, Patrick Cabrol2, Phil Pietraski2 and Ravikumar V. Pragada2 

1 Polytechnic Institute of New York University, USA,   


2 InterDigital Communications, LLC, USA,,, and 





Abstract—This work investigates the propagation 

characteristics of an office building in the 60 GHz band. From 

reflection and scattering measurements of several painted and 

un-painted common building materials recorded at 60 GHz, the 

complex permittivity and Lambert’s Law scattering coefficient of 

each material are extracted. Diffraction measurements at a 

building corner at 60 GHz are also presented and analyzed. 

Lastly, power angular profiles of building penetration and 

scattering at 60 GHz are presented and used to characterize the 

outdoor to indoor propagation, and the significant scatterers on 

a building surface, respectively. 


Index Terms—60 GHz, Buildings, Diffraction, Millimeter 

Wave, mmW, NLOS, Penetration, Reflection, Scattering, Urban. 



Many cellular, back-haul and peer-to-peer applications [1]-


[3] have been proposed for the 57–64 GHz millimeter wave 

(mmW) unlicensed band, also known as 60 GHz band. These 

applications will utilize directive antenna arrays at the 

transmitter and receiver to perform beamforming and achieve 

multi-gigabit data rates. To assist in the simulation and 

planning of such applications, a measurement campaign was 

carried out to investigate various wave propagation 

interactions with an office building. 


Reflection and scattering measurements at 60 GHz of 

several painted and un-painted building materials are presented 

in this work and then used to extract each material’s complex 

permittivity and scattering coefficient. Past works [4]-[9] have 

mostly focused on reflection and transmission characteristics 

of various building materials at 60 GHz and have largely 

neglected their rough surface scattering characteristics which 

cause angular dispersion in the received signal. A scattering 

profile from a brick at 60 GHz was given in [8] and empirical 

investigations of scattering select materials at higher 

frequencies (69-74 GHz, 94 GHz) were presented in [10], [11].  

 For outdoor applications, the presence of a building can 

cause shadowing or conversely, provide an alternate ray path 

to beamform along. Limited work has been performed for 60 

GHz band. Past works for corner diffraction have focused on 

cellular applications at 28 [12] and 40 GHz [13], and 

diffraction from metal and wooden wedges at 60 GHz [14]. 

Two sets of building corner diffraction measurements [15] are 

presented and then compared to the absorbing screen 

diffraction model.  



Figure 1. Block diagram of 60 GHz measurement setup. 


 In addition to the diffraction from building corners, the 

columns, window frames, etc. on building surfaces are 

expected to give significant contributions to the received 

signal. Knowing where the pertinent scatterers on the surface 

are, can speedup beam-finding times and enhance 

performance. Our findings through a set of measurements 

show that the majority of power arrives in the horizontal plane 

containing the transmitting and receiving antennas. 


For femtocell applications in which the transmitter is inside 

a building and receiver is outside, or vice versa, understanding 

the propagation into and out of buildings is paramount. 

Limited work was found in the literature. Most works focus on 

transmission through uniform slabs of building material [9]. 

We will present angular power profile measurements of a radio 

link where one end of the link is located in an office building 

near and far from the windows.      


The organization of the paper is as follow. The reflection 

and scattering properties of select building materials are 

characterized in Section II. Measurements of corner diffraction 

and building scattering are presented and analyzed in Section 

III. Lastly, in Section IV, outdoor to indoor propagation 

measurements are presented.  




A. Measurement Equipment and Setup 

The measurement equipment setup illustrated by the block 


diagram in Fig. 1 was used to record the received power at 60 

GHz. In the individual measurement scenarios, the antennas, 

their heights and positioning systems varied. To model the 

effect of antenna arrays at the transmitter (TX) and receiver 

(RX), the measurements used directive vertically-polarized V-

band horn antennas and lens antennas with 24 and 34 dBi gain, 

and 11 degree and 4 degree 3-dB-beamwidths, respectively. 



10 GHz



(w 25dB pad)









Vector Signal 

AnalyzerV-Band Horn



Gain = 20dB


NF = 4dB


Input Range: 





7.4GHz – 14.9GHz



















The max EIRPs of the transmitter were 15.6 and 25.6 dBm, 

respectively. For more details on the setup refer to [15]. 


The measurement testbed used for our small-scale building 

model measurements [16] was used to perform the reflection 

and scattering measurements on the building materials listed in 

Table I. To perform scattering measurements for an incident 

angle θi, the transmit antenna was moved to the desired θi at 

distance ri from the focal point of the setup, while the receive 

antenna was moved in an arc of constant distance rs from the 

focal point, so that θs spanned a desired range of angles as 

shown in Fig. 2(a). To perform reflection measurements, both 

antennas were moved so that θs = θi.  


All power measurements are normalized to the received 

power from a large metal sheet when θs = θi. These relative 

measurements are called the Normalized Power (NP). Note 

that from image theory, the received power from a large metal 

sheet is equivalent to the free-space power for the antenna 

separation rs + ri = 1 + 1 = 2 m. For reflection measurements, 

NP is approximately equal to the magnitude squared of the 

reflection coefficient |Γslab|2.  


B. Reflection Measurements and Relative Permittivities 

Reflection coefficient |Γslab| measurements were recorded at 


60 GHz for the building materials listed in Table I. As an 

example, measurements for a ceiling tile and a concrete block 

(CMU) wall are scatter plotted versus reflection angle θr = θi = 

θs in Figs. 3(a)-(b). To extract the complex relative permittivity 

εr of each material from the measurements, we utilize the same 

approach used in [4]-[7] where the material under test is 

treated as an infinite homogeneous slab. Using this 

assumption, the reflection coefficient Γslab can be expressed as 





,2 2



1 ( , )

1 ( , )




slab TE TM r rj

TE TM r r







δ ε θε θ




Γ = Γ


− Γ

,              (1) 



where 𝛿 = !!!! 𝜀! − 𝑠𝑖𝑛!(𝜃!), λ = 5 mm is the wavelength 

and  ∆ is the thickness of the slab in meters. ΓTE,TM (εr, θr) is 

either the transverse electric (TE) or transverse magnetic (TM) 

Fresnel reflection depending on the polarization of the incident 

wave relative to the slab. For our measurements, the incident 

wave was TE polarized.  

 The estimated complex relative permittivity εr was then 

found from minimizing the prediction error from (3) to 

measurements. The estimated εr for all materials are listed in 

Table I. Example predictions for the ceiling tile and CMU wall 

using the estimated εr are also plotted in blue in Figs. 3(a)-(b). 

From these figures, it is seen that the homogeneous slab model 

gives good prediction of a materials Γslab. This is also true for 

the other materials listed in Table I. 


To investigate the effect of paint, measurements were 

recorded for painted and unpainted drywall. The semi-gloss 

paint with primer appeared to affect the estimated εr of drywall 

as seen in Table I. While the flat-paint which was not applied 

with primer, did not appear to have any effect. It remains to be 

determined whether the thickness of the dried paint and/or the 

composition of the paints caused this change.  








Figure 2. (a) Building material testbed , (b) horn antenna on 

pan-tilt motor.   




































193.7 3.3


  j0.38 11.3 -­‐17.1



  Wall 92 2.55


  j0.43 14.7 -­‐17.3





12.7 3.0


  j0.54 17 -­‐


Drywall 12.7 2.26


  j2.4*10-­‐3 0.09 -­‐12.5







12.8 2.77


  j1.9*10-­‐2 0.6 -­‐








12.8 2.28


  j2.4*10-­‐3 0.09 -­‐14.2


Plexiglass 2.2 2.70


  j0.26 8.6 -­‐

Glass 12.7 6.55


  j0.20 4.3 -­‐

Wood 5.1 2.8


  j4.0*10-­‐2 1.3 -­‐



  Tile 15.9 1.55


  j2.6*10-­‐2 1.12 -­‐11.9











Figure 3. Reflection coefficient magnitude |Γslab| measurements 

and predictions for (a) ceiling tile and (b) CMU wall. 


0 10 20 30 40 50 60 70 80 90













θr [degrees]


| Γ



b |








0 10 20 30 40 50 60 70 80 90













θr [degrees]


| Γ



b |










Also listed in Table I is the attenuation parameter α of each 

material which was calculated from its εr [6]. α is the rate of 

absorption loss incurred by propagating through a material. 

Note that this loss does not include the transmission and 

reflection loss at the material-air boundaries. The CMU and 

brick walls commonly used in exterior walls were both found 

to have very high attenuation with α > 11 dB/cm. While glass 

was found to have much lower attenuation with α = 4 dB/cm. 

Accounting for the smaller thickness of glass, these results 

suggest that dominant contribution from waves propagating 

into and out of buildings are those that propagate through 

windows rather than walls. 

 For interior walls, drywall has a small α which promotes 

penetration, while cement backerboard, which is commonly 

used as a substrate for tiles, has very high attenuation. This 

suggests the feasibility of non-line of sight (NLOS) 

communication between certain rooms separated by drywall, 

though a more complete study which includes the inner 

structure (eg., multi-layers [4], insulation and studs) should be 



C. Scattering Measurements and Lambertian Model 

Scattering measurements at 60 GHz were recorded while 


the transmitting antenna at a fixed θi, while the receiving 

antenna was moved over a range of θs. An example for a CMU 

wall with θi = 45° is shown in Fig. 4 where the normalized 

power NP in dB is plotted versus θs. Also plotted in blue is the 

power contribution from a single reflected ray using ϵr = 3.3 – 

j0.38 from Table I. In Fig. 4, the scattering is seen to be 

dominant in the region θs < 20°, where the measured power is 

greater than that predicted by reflection. Note that the shape of 

the blue curve is partially dependent on the antennas used, so 

that for a set of more directive antennas, the blue curve would 

have a narrower shape. 


To predict the average total scattered power for the θs < 20° 

region, the surface was segmented into K patches each of area 

A m2. The bi-static scattering equation [17] was then applied to 

each patch assuming a Lambert’s Law model (σ = γ cos(θi) 

cos(θs)). The average power <Pr> assuming each patch had 

uniformly random phase, was then the power sum over all 

patches. Thus,  





3 2 2

1(4 )




r t

k kTX kRX





λ σ

π =


= ∑  .  (2) 


where Pt is the transmitted power in watts, RkTX is the distance 

in meters from the TX antenna to the kth slab and RkRX is the 

distance from the kth slab to the RX antenna. 

 To extract γ, a 0-watt-error criterion between predicted 

scattered power and measurements was enforced. Note that, a 

locally ergodic assumption was used where the variation 

caused by different realizations of the random surface was 

approximated by the local variation in θs of the received signal. 


For the example in Fig. 4, a value of γ = 0.02 was 

computed and used to plot the green curve in Fig. 4. The level 

of the scattered contribution relative to the reflected 


contribution in and near the specular direction (θs = θi = 45°) 

suggested that the rough scattering contribution (2) was 

relatively weaker to the reflected contribution. This resulted in 

very little angular dispersion in and near the specular direction. 

Similar results were found for the other materials in Table I.  


Note that the ceiling tile has the greatest γ value in Table I. 

This was because the size of the ceiling tile was not large 

relative to the antenna pattern footprint, so the diffraction from 

the edges was significant. All other materials in Table I were 

large enough so that the edge effects were negligible.  





The TX antenna and RX antenna were each placed on push 

carts for the building corner diffraction, scattering and 

penetration measurements. The pointing of the antennas was 

performed using pan-tilt motors shown in Fig. 2(b) that have 

0.0032⁰ angle resolution. 


A. Corner Diffraction  

 Diffraction coefficient magnitude |D| measurements for 

two different corners were recorded when the RX antenna was 

in the shadowed region (θ < 0° in Fig. 5) of each corner [15]. 

The measurements are scatter plotted in Fig. 6.  




Figure 4. Scattering measurements from a CMU wall (ϵr = 3.3 

– j0.38) and simulated reflection and scattering curves. 




Figure 5. Diffraction at a building corner. 




Figure 6. Comparison of diffraction coefficient |D| 

measurements and absorbing screen diffraction coefficient. 


0 20 40 60 80 100















Scattering Angle θs [degrees]











r N










Reflected Contribtuion

Scattered Contribution


-70 -60 -50 -40 -30 -20 -10 0
























t |








θ [deg]





Corner 1 Measurements

Corner 2 Measurements

Abosrbing Screen




To model the angular dependence of the diffraction, we 

compared these measurements to predictions from a semi-

infinite absorbing screen with a knife edge corner whose D is  



( ) 2 1 cos( ) 2 2

2sin( )2


S S SD f jg



π θ



θ π ππ


⎡ ⎤⎛ ⎞ ⎛ ⎞+

= − +⎢ ⎥⎜ ⎟ ⎜ ⎟⎜ ⎟ ⎜ ⎟⎢ ⎥⎝ ⎠ ⎝ ⎠⎣ ⎦


.     (3) 



Here θ is the angle the diffracted ray makes with the shadow 

boundary as seen in Fig. 5, and f, g, and S are defined in [18]. 

The absorbing screen predictions are plotted as the dotted line 

in Fig. 6 and are seen to give good comparison to the 


 As an example, consider an urban scenario in which the TX 

and RX are located on adjacent sides of a building, so that θ ≈ 

90°. From the measurements and predictions in Fig. 6, corner 

diffraction involves a large loss with |D| ~ -40 dB. Thus, it is 

the scattering from the clutter in the street (e.g., cars and 

lamppost) which will provide the dominant contribution to the 

received signal [15].  

 Conversely, for the case in which the TX and RX are 

located on the same street and the line-of-sight (LOS) path is 

blocked (e.g., humans [15], etc.), the TX and RX can use a 

corner diffracted ray to beamform along. Though, only 

shallowly diffracted ray paths (θ < 10°) should be considered 

because of the large loss. Note that due to the symmetrical 

property (3), |D(θ = 10°)| ≈ -20° as seen in Fig. 6.  


B. Building Surface Scattering 

Building scattering measurements were recorded using the 


setup depicted in Fig. 7. The TX and RX antennas were 

pointed at different portions of the wall using the pan-tilt 

antennas. The received power from the point of view of the 

RX antenna normalized relative to the LOS power for 7.5 m is 

plotted in Fig. 8. The majority of power was observed to arrive 

in the horizontal plane (elevation angle = 0°) containing the 

TX and RX antennas at 0°, 25° and 40°. The 0° and 40° humps 

correspond to the vertical columns on the building surface 

shown in Fig. 7. The specularly reflected contribution 

corresponds to the hump at 25°. Other humps outside of the 

horizontal plane correspond to features on the building surface 

such as window sills. These 60 GHz results are similar to UHF 

band measurements [19], in which features on the building 

surface such as balconies, contributed significantly to the 

received power angle profile.  



To investigate the propagation into and out of buildings at 


60 GHz, two received power angular profiles were recorded 

when the TX was located at ground level outside a building 

while the RX was located on the third floor of the building at 

the two locations illustrated in Fig. 9. The first location 

denoted by RX1 in Fig. 9 was near a window, so the RX 

antenna had LOS with the TX antenna. The second RX 

location was away from the window as shown in Fig. 9, so that 

the TX and RX antennas were NLOS and there were 3 office 

cubicles separating the RX antenna and the nearest window.  


The power angular profile recorded when the RX antenna 

was located near the window is plotted in Fig. 10(a). There are 

three dominant contributions seen in the profile. The largest 

contribution is the direct contribution (5° Azimuth, -15° 

Elevation) that penetrates the window. Lesser yet still 

significant contributions were found to scatter off the top and 

sides of the window frame. The profile recorded when the RX 

antenna was located further away from the window is plotted 

in Fig. 10(b). For this case, the dominant contributions arrive 

in the vertical plane (VP) containing the TX and RX antennas. 

The dominant contribution (5°, 20°) was found to propagate 

through the window bisected by the VP and then reflect/scatter 

from the ceiling. A smaller contribution (5°, -5°) diffracted 

from the window frame and then was further attenuated by the 

clutter in the environment before reaching the RX antenna. 

Note that in both RX locations, other arrivals diffracted from 

other windows away from the VP or those penetrating the 

walls were found to be severely attenuated and did not affect 

the angular dispersion of the received signal. 





Figure 7. Building scattering measurement setup 




Figure 8. Scattering profile from a building surface.  




Figure 9. Outdoor to indoor measurement setup for RX 

antenna located near to (RX1) and away from (RX2) window. 





In this work, several different sets of measurements were 


presented and analyzed. The reflection and scattering 

properties of a variety of building materials were extracted 

from measurements. Semigloss paint with primer was found 

to have an effect on the relative permittivity of a material. 

Outer wall building materials were seen to have very high 

attenuation coefficients, so that building penetration is 

expected to be least attenuated through windows. Rough 

surface scattering from the considered building materials was 

found to have little effect on the angular dispersion of the 

received signal. 


Diffraction measurements were recorded for two building 

corners. The absorbing screen model was found to model 

relatively well the angular dependence of the diffraction. For 

some cases, the diffraction loss for turning corners was found 

to be very large, so that the scattering form street furniture 

(e.g., lamposts) was expected to be dominant. 


From a building scattering profile of an office building, the 

dominant contributions to received power were found to 

arrive mostly in the horizontal plane containing the TX and 

RX antennas. Several lesser out-of-plane contributions were 

found to come from window ledges.  


For propagation into a building, when the TX and RX 

antennas have LOS, the dominant arrival was the direct ray. 

Though scattering from the window frame gave significant 

contributions to the received signal. When the RX was located 

away from the window, the dominant contribution was ceiling 

diffracted and lied in the vertical plane. 









Figure 10. Power angular profiles when RX is located on the 

third floor (a) near to; (b) away from the window 



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