Report on measurement campaigns for total radiated power of UltraWideBand (UWB) device to support EU RF spectrum regulation.
Date: 2023-11-24
Institutions: Joint Research Centre
Subjects: EU Member State, electromagnetic interference, measuring equipment, metrology, regulation of telecommunications, research method, research report, spectrometry, waveband

ISSN 1831-9424

JRC TECHNICAL REPORT

Report on Measurement Campaigns for 
Total Radiated Power of one 
UltraWideBand (UWB) device to support 
EU RF spectrum regulation 

Baldini, G., Chareau, J., Bonavitacola, F.

2023 

 EUREUR 31746 EN 31746 EN

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
This publication is a Technical report by the Joint Research Centre (JRC), the European Commission’s science and knowledge 
service. It aims to provide evidence-based scientific support to the European policymaking process. The contents of this 
publication do not necessarily reflect the position or opinion of the European Commission. Neither the European Commission 
nor any person acting on behalf of the Commission is responsible for the use that might be made of this publication. For 
information on the methodology and quality underlying the data used in this publication for which the source is neither Eurostat 
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of material on the maps do not imply the expression of any opinion whatsoever on the part of the European Union concerning 
the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or 

Contact information  
Name:  Gianmarco Baldini 
Address: Via Enrico Fermi, 2749 
Email: gianmarco.baldini@ec.europa.eu 
Tel.: +39 0332 786618 

EU Science Hub 
https://joint-research-centre.ec.europa.eu 

JRC134860 

EUR 31746 EN 

PDF  

ISBN 978-92-68-09643-7  

ISSN 1831-9424  

doi:10.2760/73717   KJ-NA-31-746-EN-N 

Luxembourg: Publications Office of the European Union, 2023 

© European Union, 2023 

The reuse policy of the European Commission documents is implemented by the Commission Decision 2011/833/EU of 12 
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How to cite this report: Baldini, G., Chareau, J. and Bonavitacola, F., Report on Measurement Campaigns for Total Radiated Power 
of UltraWideBand (UWB) device to support EU RF spectrum regulation, Publications Office of the European Union, Luxembourg, 
2023, doi:10.2760/73717, JRC134860.  

 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Abstract ................................................................................................................................................................................... 1 

Acknowledgements ............................................................................................................................................................ 2 

1 

Introduction ..................................................................................................................................................................... 3 

1.1  Background information .................................................................................................................................... 3 

1.2  Scope of the report ............................................................................................................................................... 3 

1.3  Structure of the report ........................................................................................................................................ 4 

2  Test bed and materials ................................................................................................................................................. 5 

2.1  Test bed anechoic chamber ............................................................................................................................... 5 

2.2  Referential for reporting the test results ...................................................................................................... 6 

2.3  Materials ................................................................................................................................................................. 8 

2.3.1 

Description of the test equipment ....................................................................................................... 8 

2.3.2  Device Under Test (DUT) description and configuration ............................................................... 8 

3  Methodology for calibration and measurements collection ............................................................................ 11 

3.1  Calibration and parameter calculation ......................................................................................................... 11 

3.2  Consistency check of channel power calculation ..................................................................................... 12 

3.3  Effect of Device Under Test (DUT) orientation ............................................................................................ 14 

4  Results............................................................................................................................................................................ 18 

4.1  Radiation patterns ............................................................................................................................................. 18 

4.2  Result summary ................................................................................................................................................ 20 

4.3  Discussion on the results................................................................................................................................. 22 

5  Conclusions ..................................................................................................................................................................23 

References ......................................................................................................................................................................... 24 

List of abbreviations and definitions ........................................................................................................................... 25 

List of figures ...................................................................................................................................................................... 27 

List of tables ....................................................................................................................................................................... 28 

i 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Abstract  

Ultra-Wideband  (UWB)  is  a  communications  technology  that  employs  a  wide  bandwidth  (typically  defined  as 
greater  than  20%  of  the  centre  frequency  or  500MHz).  The  transmission  centre  frequency  varies  with  the 
identifier  of  the  communication  channel  (e.g.,  6.4896  GHz).  Because  of  such  large  radio  frequency  spectrum 
occupancy,  spectrum  regulations  have  to  be  carefully  defined  to  avoid  the  risk  of  interference  with  other 
wireless services coexisting in the same bands. 

The  next  update  cycle  of  the  UWB  regulation  in  the  European  Union  will  be  started  based  on  the  System 
Reference  Document  (SRD)  SRDoc  (TR  103  750)  from  the  European  Telecommunication  Standardization 
Institute  (ETSI)  asking  for  a  band  extension  of  some  applications  (mainly  location  tracking  and  sensor 
applications) up to 10.6 GHz. The focus of the new investigations in SE24 will be the band 8.5 GHz to 10.6 GHz using 
a set of mitigation techniques and mechanisms to protect the incumbent services in the band (e.g., X-band radio 
navigation and radiolocation systems).  

One of the mitigation factors to be considered is the Total Radiated Power (TRP) spectral density (SD) TRPSD. The 
TRPSD  parameter  is not new in  the UWB regulation  and has been used  in  the sensor  regulation of UWB since 
several  years.  Nevertheless,  systematic  measurements  of  the  value  using  typical  UWB  devices  for  other 
application have never been performed. In order to be able to use realistic values in the Conférence européenne 
des administrations des postes et des télécommunications (CEPT), a study was conducted in the JRC on one 
UWB device to support a realistic evaluation of the interference effects of UWB into other systems and services. 

1 

 
 
 
Acknowledgements  

We acknowledge the valuable contribution of Dr Friedbert Berens for defining the context of the measurement 
campaign of the UWB device and other significant technical input. 

Authors 

Gianmarco Baldini 

Jean-Marc Chareau, 

Fausto Bonavitacola 

2 

 
 
1 

Introduction  

1.1  Background information 

Ultra-wideband (UWB) wireless communication is a technology for transmitting large amounts of digital data 
over a wide frequency spectrum using different modulation schemes including short-pulse, low-powered radio 
signals  or  an  aggregate  of  at  least  500  MHz  of  a  narrow-band  carrier  with  orthogonal  frequency-division 
multiplexing (OFDM).  

Then, UWB commonly refers to a signal or system that either has a large relative bandwidth (BW) that exceeds 
20% or a large absolute bandwidth of more than 500 MHz. 

UWB  technology  has  a  number  of  applications 
communications and positioning.  

including  non-cooperative  radar 

imaging,  wireless 

Due to its large spectrum occupancy, a UWB radio system is particularly robust against multi-path effects. For 
example,  in  positioning,  UWB  can  be  used  to  determine  the  "time  of  flight"  of  the  transmission  at  various 
frequencies. This  helps overcome  multipath propagation, since  some  of the  frequencies have  a  line-of-sight 
trajectory, while other indirect paths have longer delays. 

This study is focused on the application of UWB technology to wireless communication and positioning. In both 
applications, the potential risk of UWB technology is to create interference to other wireless services occupying 
the same band, taking in consideration not only the large bandwidth of the UWB signal but also that spectrum 
regulations around the world allow the use of UWB technology in a large portion of the RF spectrum, where other 
services are also granted the permission to transmit. To mitigate the risk of wireless interference, the emission 
power  of  UWB  devices  is  limited  through  “emissions  masks”  or  other  techniques  are  used  including  the 
detection of the presence of wireless service in the space in a specific RF spectrum band. In case of positive 
detection of a primary wireless service, the UWB device change the transmit band to another band where no 
wireless service was detected. 

Radio  Frequency  spectrum  regulations  around  the  world  set  precise  rules  for  the  UWB  wireless  devices  to 
operate. 

In the European Union, the European UWB regulation is being driven by a permanent mandate of the European 
commission to CEPT. Under this permanent mandate all spectrum requests by industry via ETSI SRDocs in the 
domain of UWB are handled. The last update of the CEPT regulation have been published in 2022 as amendment 
of the ECC decision (06)04. The corresponding EC regulation will be updated in the run of 2023 based on a CEPT 
report under finalization in CEPT WGFM. 

The next update cycle of the UWB regulation will be started based on the SRDoc (TR 103 750) from ETSI asking for 
a band extension  of  some applications (mainly  location tracking  and  sensor  applications)  up to 10.6 GHz. The 
focus of the new investigations in SE24 will be the band 8.5 GHz to 10.6 GHz using a set of mitigation techniques 
and mechanisms to protect the incumbent services in the band.  

One of the mitigation factors to be considered in the evaluation of the coexistence between UWB and incumbent 
services in the band is the total radiated power spectral density (TRPSD). This value is a measure for the average 
of the emitted interference power in all directions in contrast to the Effective Isotropic Radiated Power (EIRP) 
value, which give the worst-case highest emission level into one single direction. Especially for small and body 
worn devices the TRPSD is typically significantly lower than the EIRP value. The TRPSD parameter is not new in the 
UWB  regulation  and  it  has  been  used  in  the  sensor  regulation  of  UWB  for  several  years.  Nevertheless, 
systematic measurements of the value using typical UWB devices for other applications were never performed.  

In order to be able to use realistic values in the CEPT investigations, it is important to execute measurements of 
total  radiated  power  from UWB  devices  in  a  controlled  environment  as  the  European  Commission  (EC)  Joint 
Research Centre (JRC) Radio Frequency (RF) laboratory. These measurements would be an important element 
for the realistic evaluation of the interference effects of UWB into other systems and services. 

Then, the purpose of this report is to describe the Radio Frequency (RF) measurements conducted in the JRC on 
a sample of UWB transmitter used for positioning applications. 

1.2  Scope of the report 

The aim of the measurements performed on this UWB module is to assess a test setup for the measurement of 
TRPSD  as  proposed  in  Annex  A  of  the  System  Reference  document  (SRdoc)  ETSI  TR  103  750  [2].  This  initial 

3 

 
 
implementation applies only to the category of small form factor devices whose weight and size are compatible 
with our facility. 

This report does not assess the compliance of the tested device and uses the referenced standard and technical 
report only as a guide for the implementation of the tests. 

1.3  Structure of the report 

The structure of this report is following: 

—  Section 2 describes the test bed and materials including a description of the shielded chamber used for the 

tests, the test equipment and the reference framework (e.g., angles and position). 

—  Section 3 describes the methodology to perform the measurements, the calibration process and provides 

some considerations on the uncertainties during the measurement phase. 

—  Section 4 provides the results of the measurements and an analysis. 

—  Section 5 provides the conclusions of the report. 

4 

 
 
 
2  Test bed and materials  

2.1 

Test bed anechoic chamber  

Experiments were carried out in the JRC’s Shielded Anechoic Chamber (SAC) of the DG JRC of the European 
Commission, located in Ispra, Italy.  

The device under test (DUT) was a UWB module development kit, Qorvo DWM3001CDK (described more in detail 
in sub-section 2.3.2), placed in the quiet zone of the chamber on a two-axis positioner as shown on the picture of 
Figure 1. On the left in the foreground, appears a double-ridged horn antenna used as probe antenna to measure 
the radiation emitted by the DUT. 

A  schematic  of  the  measurement  setup  is  shown  in  Figure  2.  The  DUT  was  placed  on  a  two-axis  system 
consisting of a compact table providing rotation around the vertical axis and a turn unit for the rotation around 
the horizontal axis. The aperture of the probe  antenna was  placed at a distance d  from the centre of the  DUT 
antenna.  Measurements  were  performed  at  two  different  distances,  i.e.  d=1  m  and  d=3  m.  Absorbers  were 
removed  from  the  floor  for  the  measurements  at  d=1  m  because  there  was  not  enough  space  between  the 
compact  table  and  the  probe  antenna  tripod  whereas  twelve  pieces  of  absorbers  were  presents  for  the 
measurements at d=3 m in the full anechoic configuration of the chamber. 

A low noise amplifier (LNA) was connected to the probe antenna, followed by a series of coaxial cables linked to 
a  spectrum  analyser  situated  in  the  laboratory  below  the  chamber.  A  computer  was  used  to  acquire  the 
spectrum trace and to control the axes. 

Figure 1: Over The Air (OTA) measurement set up in the Shielded Anechoic Chamber (SAC) in full anechoic configuration. 

5 

 
 
 
 
 
d

LNA

Antenna

DUT

e
c
i
v
e
d
n
r
u
T

Shielded Anechoic Chamber

Compact table

Spectrum Analyzer

Axis Controller

LAN

Laboratory

2.2  Referential for reporting the test results 

Figure 2: Measurement setup 

The  terminology  and  coordinate  system  are  taken  from  the  CTIA  Test  Plan  for  Wireless  Devise  Over-the-Air 
Performance [3].  A  spherical coordinate system is linked  to the  DUT as shown  in Figure 3. The phi (φ) axis  is 
defined as being along the Z-axis. As the phi axis rotates, the orientation of the theta axis varies with respect to 
the DUT. The green arrow identifies the direction of the probe antenna (Horn antenna). 

The two polarizations of the measured electric field are defined in terms of the two rotation axes: 

•  φ-polarization is along the direction of motion when the phi axis rotates 
•  Θ-polarization is along the direction of motion when the theta axis rotates 

In the same manner as the combined-axes system shown in Appendix A of the CTIA test plan and reproduced in 
Figure  4,  our  Z-axis  is  in  fact  the  horizontal  axis.  Therefore,  the  phi  polarisation  is  measured  when  the 
polarisation of horn antenna is orientated vertically. The horn antenna was rotated by 90° to measure the theta 
(Θ) polarisation. 

This referential differs from the one described in clause 5.6 of EN 303 883 [1] where θ is the elevation angle and 
is independent of phi. In the present report, phi and theta are combined axes. 

6 

 
 
 
 
Figure 3: Coordinate system associated with the DUT 

Figure 4: Typical setup for a combined-axes system as shown in Appendix A of the CTIA test plan [4]. 

7 

 
 
 
 
 
 
The compact table was rotated around the vertical axis (theta axis) from 5° to 175° in steps of 10°. For each theta 
angle, the turn unit, holding the DUT, was rotated from 0° to 360° in steps of 10°. In total, radiation patterns were 
measured for 18 values of theta and 37 values of phi. 

2.3  Materials 

2.3.1  Description of the test equipment 

The test equipment and tools used for the test are listed in Table 1. 

Table 1: List of equipment used for the test. 

Description 

Manufacturer 

Model 

Notes 

Shielded Anechoic Chamber 

Global EMC 

dimensions  

7m x 3.5m x 3m 

Compact table 

INNCO Systems 

CT1000 

Turnable unit 

INNCO Systems 

DE3700-RH 

Standard Horn Antenna 

Schwarzbeck 

BBHA 9120D 

Low Noise Amplifier 

B&Z Technologies  BZ-04000800-071040-

152020 

Spectrum analyser 

Keysight 

N9030B 

Signal generator 

Rohde & Schwarz 

SMM100A 

Power meter 

Rohde & Schwarz  NRP50SN 

Rotating 
platform 
where the UWB device is 
deployed 

This  horn  antenna  was 
selected  because 
its 
frequency 
operating 
range is suitable for the 
UWB transmissions 

The  signal  generator 
was used for calibration.

2.3.2  Device Under Test (DUT) description and configuration 

The device under test (DUT) was a UWB module development kit module development kit, Qorvo DWM3001CDK. 

Qorvo's  DWM3001CDK  has  been  developed  as  a  design  kit  for  the  DWM3001C  fully  integrated  (UWB)  module 
based on the Qorvo DW3110 IC. This kit can be used to evaluate hardware performance as a Time Direction of 
Arrival (TDoA) Tag and build an evaluation real time location system (RTLS) for indoor positioning1. 

Two micro Universal Serial Bus (USB) ports connect to the J-Link and DWM3001C USB interface. Two micro USB 
ports connect to the J-Link and DWM3001C USB interface. The board can be powered from either of these USB 
ports, a Raspberry Pi interface, a battery or an external power supply 

The DUT was operated using the CLI interface. The frame configuration was the default one as seen after the 
command ‘uwbcfg’ on the terminal screen. The command ‘uwbcfg’ was used only to change the UWB channel 

1 Text extracted from https://www.qorvo.com/products/p/DWM3001CDK. 

8 

 
 
 
 
 
 
 
 
                                                                                      
 
from 5 to 9. The default Tx power parameters were kept unchanged as seen after the command ‘txpower’. Finally, 
the application command ‘tcfm’ was used to force the DUT to transmit frames with a repetition time of 1 ms. 

The device was set to transmit in UWB channel 5 and 9 whose centre frequencies are respectively 6489.6 MHz 
and 7987.2 MHz. 

Figure 5: Screen shot of the terminal interface. 

The transmitted signal was captured during 2.5 ms at a sampling rate of 600 MHz using the IQ Analyzer function 
of the spectrum analyser. The time trace shown in Figure 6 confirms the repetition time of 1 ms. The duration of 
the burst is 121 μs leading a duty cycle of 12.1%. 

Three different waveforms can be identified when zooming on a single frame (Figure 7). The initial waveform of 
lower peak amplitude may correspond to the Synchronization field SYNC. The second waveform could be the 
Start of Frame delimiter SFD and the third one a combination of the Physical layer Header (PHR) and Payload 
Field.  Further  zoom  on  the SYNC  field  shows  that  the signal  consists  of  pulses  whose  duration  is  about  2  ns 
(Figure 8). 

9 

 
 
 
 
 
Figure 6: Amplitude of UWB signal versus time. 

Figure 7: Amplitude of UWB signal during one frame. 

Figure 8 Amplitude of preamble pulses. 

10 

 
 
 
 
 
 
 
3  Methodology for calibration and measurements collection 

3.1  Calibration and parameter calculation 

Power spectral density Effective Isotropic Radiated Power (EIRP) values are calculated, for each polarisation 
(θ-polarisation and φ-polarisation), theta and phi angles, and measured frequency in the following way: 

EIRP_SDθ(θ,φ,f) = Pθ(θ,φ,f) + FSPL - GA – CF and EIRP_SDφ(θ,φ,f) = Pφ(θ,φ,f) + FSPL - GA – CF where: 

●  Pθ is a sample of the spectrum trace in dBm for the θ-polarisation. 

●  Pφ is a sample of the spectrum trace in dBm for the φ-polarisation. 

●  FSPL is the Free Space Path Loss in dB. 

●  GA  is  the  probe  antenna  gain  in  dBi,  calibrated  by  the  manufacturer  at  the  very  same  measuring 

distances d=1m and d=3m. 

●  CF is a calibration factor that incorporates the Low Noise Amplifier (LNA) gain and cable losses. It 
was measured by replacing the probe antenna with a signal generator transmitting a continuous 
wave at the centre frequencies of UWB channels 5 and 9. 

●  EIRP_SDθ is the power spectral density in dBm for the θ-polarisation. 

●  EIRP_SDφ is the power spectral density in dBm for the φ –polarisation. 

The calibration parameters are summarised in Table 2. 

Table 2: Calibration parameters 

Distance (m) 

1 

1 

3 

3 

Frequency (MHz) 

6489.6 (channel 5) 

7987.2 (channel 9) 

6489.6 (channel 5)   7987.2 (channel 9) 

FSPL (dB) 

48.69 

Antenna gain (dBi) 

10.42 

Calibration  factor  CF 
(dB) 

36.6 

50.50 

10.83 

36.6 

58.24 

11.46 

36.1 

60.04 

11.35 

36.1 

The resulting mean EIRP Spectral Density eirp_sd, in mW, is the linear sum of the two polarisation components: 

𝑒𝑖𝑟𝑝_𝑠𝑑(𝜃, 𝜑, 𝑓) = 𝑒𝑖𝑟𝑝_𝑠𝑑(cid:3087)(𝜃, 𝜑, 𝑓) + 𝑒𝑖𝑟𝑝_𝑠𝑑(cid:3101)(𝜃, 𝜑, 𝑓) 

with 𝑒𝑖𝑟𝑝_𝑠𝑑(cid:3087) = 10

(cid:3254)(cid:3258)(cid:3267)(cid:3265)(cid:3268)(cid:3253)(cid:3335)
(cid:3117)(cid:3116)

 𝑎𝑛𝑑 𝑒𝑖𝑟𝑝_𝑠𝑑(cid:3101) = 10

(cid:3254)(cid:3258)(cid:3267)(cid:3265)_(cid:3268)(cid:3253)(cid:3349)
(cid:3117)(cid:3116)

the mean EIRP is calculated is the following way: 

𝑒𝑖𝑟𝑝 =

𝐵(cid:3046)
𝐵(cid:3045)

1
𝑛

(cid:3036)(cid:2880)(cid:3036)(cid:3283)

(cid:3533) 𝑒𝑖𝑟𝑝_𝑠𝑑(𝜃, 𝜑, 𝑓)

(cid:3036)(cid:2880)(cid:3036)(cid:3287)

With: 

Bs the specified bandwidth 

Br the resolution bandwidth 

n  the number of data points in the summation 

11 

 
 
 
 
 
 
 
 
 
 
 
 
il the index of the lower frequency 

ih index of the higher frequency 

The total radiation power is calculated as follows: 

𝑇𝑅𝑃 =

𝜋
2𝑁𝑀

(cid:3014)(cid:2879)(cid:2869)

(cid:3015)
(cid:3533) (cid:3533) 𝑒𝑖𝑟𝑝(cid:3435)𝜃(cid:3036), 𝜑(cid:3037)(cid:3439) sin (𝜃)
(cid:3036)(cid:2880)(cid:2869)

(cid:3037)(cid:2880)(cid:2869)

Similarly, the total radiation power spectral density is: 

𝑇𝑅𝑃𝑆𝐷 =

𝜋
2𝑁𝑀

(cid:3014)(cid:2879)(cid:2869)

(cid:3015)
(cid:3533) (cid:3533) 𝑒𝑖𝑟𝑝_𝑠𝑑(cid:3435)𝜃(cid:3036), 𝜑(cid:3037)(cid:3439) sin (𝜃)
(cid:3036)(cid:2880)(cid:2869)

(cid:3037)(cid:2880)(cid:2869)

Where N is the number of measured theta points (18 points from 5° to 175°) and M the number of phi points (37 
points from 0° to 360°). Note that j goes from 1 to M-1 because there are 36 intervals from 0° and 360° in 10° steps. 

3.2  Consistency check of channel power calculation 

Instead of using the Channel Power function of the spectrum analyser as specified in clause 5.3.1.3 of EN 303 883 
[1], the Channel Power was calculated from the spectrum trace, recorded for each orientation of the DUT. This 
deviation from the standard allows to calculate the channel power in different bandwidths and to estimate the 
TRPSD for each measured frequency point. The correctness of the post processing in assessed in the following. 

The channel power is calculated, in a specified bandwidth, by linear summation of samples of the spectrum trace 
as follows: 

𝑃(cid:3030)(cid:3035) = 10 𝐿𝑜𝑔(cid:2869)(cid:2868)( 

𝐵(cid:3046)
𝐵(cid:3045)

1
𝑛

(cid:3036)(cid:2880)(cid:3036)(cid:2870)
  (cid:3533) 10(
(cid:3036)(cid:2880)(cid:3036)(cid:2869)

(cid:3017)(cid:3284)
(cid:2869)(cid:2868)

)

  ) 

with   Pch the channel power in dBm 

Bs the specified bandwidth 

Br the resolution bandwidth 

n the number of data points in the summation 

i1 index of the lower frequency 

i2 index of the higher frequency 

Pi a sample of the spectrum trace in dBm 

The parameters of the spectrum analyser are given in Table 3: 

Table 3: Spectrum analyser parameter 

Parameter 

Value 

Centre frequency 

6.4896 GHz 

Span 

RBW 

1 GHz 

1 MHz 

12 

 
 
 
 
 
 
 
 
 
 
Resolution filter type 

Gaussian 

Detector 

Sweep time 

Sweep points 

Average 

1 s 

1001 

Trace 

Clear write 

Sweep points and sweep time are chosen such that the power is averaged on exactly one period of the UWB 
signal, i.e. 1 ms. There is therefore no need to accumulate traces using the Max Hold mode. The value of 1001 for 
the number of sweep points allows having exactly 1 MHz between two points. 

Figure  9  is  a  screen  shot  of  the  spectrum  analyser  showing  the  spectrum  trace  in  yellow  and  the  result  of 
Channel Power measurement. The trace samples are imported in a computer for post-processing. 

Figure 9: Spectrum analyser screen shot showing spectrum trace and result of Total Channel Power calculation. 

The calculated channel power is compared to the total power measured with a power meter Rohde&Schwarz 
NRP50SN,  the  mean  power  of  an  IQ  waveform  acquired  in  a  510  MHz  bandwidth  and  the  channel  power 
calculated by the instrument.  

The results are summarized in Table 4. 

Table 4: Results of the comparison 

Method 

Measured power 

13 

 
 
 
 
 
 
 
Sum of spectrum trace 

-15.43 dBm / 1 GHz 

Power meter 

-15.4 dBm 

Sum of spectrum trace 

-15.60 dBm / 510 MHz 

Mean power of IQ waveform 

-15.64 dBm / 510 MHz 

Instrument channel power 

-15.68 dBm / 1 GHz 

There  is  a  good  agreement  between  the  power  measured  with  the  power  meter  and  the  channel  power 
calculated as the sum of the spectrum trace over 1 GHz. There is also a good agreement between the channel 
power calculated over the central 510 MHz bandwidth and the mean power of the IQ waveform acquired in a 510 
MHz analysis bandwidth. 

However, the channel power calculated by the instrument is 0.25 dB lower than the one calculated as the sum of 
the spectrum trace. This difference is because the spectrum analyser uses the noise equivalent bandwidth as 
resolution bandwidth Br instead of the 3dB bandwidth of the resolution filter RWB. In fact, the spectrum analyser 
subtracts 0.24 dB to take into account the noise equivalent bandwidth of a Gaussian filter as explained in the 
Keysight application note 5966-4008 “Spectrum and Signal Analyser Measurements and Noise” [4]. 

The  first  observation  is  that  the  correction  factor  of  0.24  dB  applied  by  the  Channel  Power  function  of  the 
spectrum analyser is not needed in the case of the tested UWB signal. 

The second observation is that although the UWB consists of very short pulses there is no negative effect due 
the impulse response of the resolution filter. 

Therefore, the method used for the measurement of the Channel Power and Power Spectral Density is validated. 

3.3  Effect of Device Under Test (DUT) orientation 

There are measurements points of the radiation pattern where the structure supporting the turn unit happen to 
be situated between the DUT and the probe antenna. Although the structure is made of low dielectric constant 
materials, it is necessary to check that it does not affect significantly wave propagation. 

Measurements  have  been  performed  with  two  different  orientations  of  the  DUT  on  the  turn  unit:  the  normal 
orientation and the reverse orientation as shown in Figure 10 and Figure 11. 

Z

Y

Z

Y

Figure 10: Normal orientation 

Figure 11: Reverse orientation 

14 

 
 
 
 
 
 
The following tables compare the results obtained with the two DUT’s orientations when transmitting in 
UWB channels 5 and 9 and for the two distances between DUT and probe antenna. 

Differences  of  ±0.5  dB  for  TRP  and  ±1  dB  for  EIRP  are  within  the  ±2  dB  measurement  uncertainty.  This 
result is also illustrated in the vertical cut of the radiation pattern of Figure 12 that displays the EIRP in 
function of theta at phi=0°. The blue and red traces correspond to the Normal and Reverse orientations 
respectively. 

Therefore, there is no need to split the measurement in two “half” spheres as noted in clause 5.6.2.2 of EN 
303 883 [1]. The full sphere can be measured without repositioning the DUT. 

15 

 
 
 
 
Table 5: Effect of the orientation of the DUT transmitting in channel 5 and measured at 1m. 

Metric 

Normal orientation  

Reverse orientation 

Difference (dB) 

EIRP (dBm) 

TRP (dBm) 

-13.15 

-20.16 

EIRP PSD (dBm/MHz) 

-38.25 

TRP PSD (dBm/MHz) 

-45.57 

-14.20 

-20.04 

-39.35 

-45.48 

1.05 

-0.12 

1.1 

-0.09 

Table 6: Effect of the orientation of the DUT transmitting in channel 9 and measured at 1m 

Metric 

Normal orientation 

Reverse orientation 

Difference (dB) 

EIRP (dBm) 

TRP (dBm) 

-13.30 

-19.72 

EIRP PSD (dBm/MHz) 

-38.11 

TRP PSD (dBm/MHz) 

-45.28 

-13.86 

-19.67 

-38.96 

-45.22 

0.56 

-0.05 

0.85 

-0.06 

Table 7: Effect of orientation DUT transmitting in channel 5 and measured at 3m 

Metric 

Normal orientation  

Reverse orientation 

Difference (dB) 

EIRP (dBm) 

TRP (dBm) 

-13.14 

-20.27 

EIRP PSD (dBm/MHz) 

-38.30 

TRP PSD (dBm/MHz) 

-45.69 

-13.28 

-19.78 

-38.14 

-45.13 

0.72 

-0.49 

-0.16 

-0.56 

Table 8: Effect of orientation DUT transmitting in channel 9 and measured at 3m 

Metric 

Normal orientation 

Reverse orientation 

Difference (dB) 

EIRP (dBm) 

TRP (dBm) 

-12.96 

-18.96 

EIRP PSD (dBm/MHz) 

-37.63 

TRP PSD (dBm/MHz) 

-44.56 

-1.13 

0.3 

-1.03 

0.39 

-11.83 

-19.26 

-36.60 

-44.95 

16 

 
 
 
 
 
 
Figure 12: Comparison of radiation patterns with Normal (blue) and Reverse (red) orientations. 

17 

 
 
 
4  Results 

4.1  Radiation patterns 

An  example  of  radiation  pattern  when  the  DUT  was  transmitting  in  channel  5  is  given  in  the  following 
figures. Figure 13 is a 3D representation of the radiation pattern whereas Figure 14 consists in eighteen 
polar  plots  of  EIRP  versus  phi  angle,  one  for  each  theta  angle.  Each  plot  shows  the  θ-polarisation 
component, the φ-polarisation component and the sum of them. A maximum EIRP of -13.2 dBm is found at 
theta=45° and phi=250°.  

Figure 15 shows the result of calculation of TRPSD versus frequency. The maximum TRPSD is found to be -
45.6 dBm/MHz at the frequency of 6392.6 MHz. It is important to note that the frequency at which TRPSD is 
maximum is not necessarily the centre frequency of the UWB channel. Therefore, it would be necessary 
to specify that the measurement of TRPSD shall be performed for all 1 MHz intervals within the operating 
frequency range and the maximum shall be retained as value of TRPSD. 

Figure 13: Example of 3D radiation pattern 

18 

 
 
 
 
 
Figure 14: Example of measured radiation pattern 

19 

 
 
 
 
Figure 15: Result of TRPSD measurement versus frequency 

4.2  Result summary 

Measurement  results  are  reported  in  Table  9  and  are  represented  graphically  in  Figure  16.  Maximum 
values  of  EIRP  and  EIRPSD  do  not  vary  significantly  with  channel  number  and  measuring  distance.  The 
maximum  mean  EIRPSD  (-37.6  dBm/MHz)  exceeds  the  limit  of  -41.3  dBm/MHz  because  the  device  was 
forced  to  transmit  with  higher  duty  cycle.  The  fact  that  TRP  and  TRPSD  values  are  more  spread  at  3  m 
measurement  distance  can  be  explained  because  their  calculation  includes  points  with  low  signal  to 
noise ratio. Finally, it is found that the TRPSD of this DUT is about 7 dB lower than its mean EIRPSD.  

This result shows that the radiation pattern is far from being isotropic because the mean EIRPSD, which is 
the emitted power spectral density in the direction of the maximum level is 7 dB higher than the TRPSD, 
which is the emitted power spectral density averaged over all directions. 

Table 9: Measurement results 

UWB 

Distance 

EIRP 

EIRPSD 

TRP (dBm) 

TRPSD 

channel 

(m) 

(dBm) 

(dBm/MHz) 

(dBm/MHz) 

5 

9 

1 

1 

-13.15 

-13.3 

-38.25 

-38.11 

-20.16 

-19.72 

-45.57 

-45.28 

20 

 
 
 
 
5 

9 

9 

5 

3 

3 

3 

3 

-13.3 

-12.96 

-13.14 

-12.93 

-37.95 

-19.9 

-19.01 

-45.2 

-44.7 

-38.25 

-37.63 

-18.96 

-44.56 

-38.3 

-20.27 

-45.69 

Figure 16: Graphical results of the measurements of EIRP (a), TRP (b), EIRPSD (c) and TRPSD (d) 

21 

 
 
 
 
4.3  Discussion on the results 

Initial measurements of radiated power transmitted by a UWB development kit module has been carried 
out in JRC’s Shielded Anechoic Chamber (SAC) to assess a test setup and a methodology for measuring 
the TRPSD.  

The following observations were made: 

● 

It is necessary that the DUT is operated in a testing mode such that it transmits continuously 
at high repetition rate (e.g. 1 ms repetition time). 

●  The  correction  that  the  Channel  Power  function  of  spectrum  analysers  apply  to  take  into 
account  the  noise  equivalent  bandwidth  of  the  resolution  filter  does  not  seem  to  be 
appropriate to UWB signals. 

●  The impulse response of the resolution filter does not affect negatively the measurement. 

●  There is no need to split the measurement in two “half” spheres as noted in clause 5.6.2.2 of 

EN 303 883 [1]. The full sphere can be measured without repositioning the DUT. 

●  For the tested device, the frequency at which TRPSD is maximum is not the centre frequency 

of the UWB channel. 

●  There are no significant differences between the results obtained at a measuring distance of 
1 meter and 3 meters. A measurement distance of 1 meter could be chosen at the condition 
that the far field requirement be met. 

●  This  result  shows  that  the  radiation  pattern  is  far  from  being  isotropic  because  the  mean 
EIRPSD, which is the emitted power spectral density in the direction of the maximum level is 7 
dB  higher  than  the  TRPSD,  which  is  the  emitted  power  spectral  density  averaged  over  all 
directions. 

22 

 
 
5  Conclusions 

This report describes the measurement campaign conducted in the JRC facilities on one Ultra Wide Band 
(UWB) device to measure the Total Radiated Power Spectral Density (TRPSD). Some observations were 
made  on  the  results  on  the  measurements  including  the  consideration  that  the  correction  that  the 
Channel Power function of spectrum analysers apply to take into account the noise equivalent bandwidth 
of the resolution filter does not seem to be appropriate to UWB signals. In addition, there is no need to split 
the measurement in two “half” spheres as noted in clause 5.6.2.2 of EN 303 883 [1]. The authors also noted 
a large variability in the radiation pattern, which is far from being isotropic. Finally, the full sphere can be 
measured without repositioning the Device Under Test (DUT). 

The  results  of  this  measurement  campaign  can  be  used  to  support  the  regulatory  activities  in  the 
European Union (EU) regarding UWB technology CEPT System Engineering SE24. 

23 

 
References  

[1].  R. S. Kshetrimayum, "An introduction to UWB communication systems," in IEEE Potentials, vol. 

28, no. 2, pp. 9-13, March-April 2009, doi: 10.1109/MPOT.2009.931847. 

[2].  ETSI  EN  303  883  -1  V1.2.1:  “Short  Range  Devices  (SRD)  and  Ultra  Wide  Band  (UWB);  Part  1: 

Measurement techniques for transmitter requirements”. 

[3].  ETSI TR 103 750 V1.1.1: “System Reference document (SRdoc); Short Range Devices (SRD) using 
Ultra  Wide  Band  (UWB);  Technical  characteristics  for  UWB  operation  in  the  frequency  band 
between 8.5 GHz to 10.6GHz”. 

[4].  CTIA  -  Test  Plan  for  Wireless  Device  Over-the-Air  Performance.  Method  of  Measurement  for 
Radiated RF Power and Receiver Performance. Version 3.8.2. April 2019. https://api.ctia.org/wp-
content/uploads/2019/04/CTIA_OTA_Test_Plan_3_8_2.pdf/ 

[5].   Keysight application note 5966-4008 “Spectrum and Signal Analyzer Measurements and Noise”. 

https://www.keysight.com/us/en/assets/7018-06765/application-notes/5966-4008.pdf. 

24 

 
 
List of abbreviations and definitions  

Abbreviation 

Definition 

BW 

CF 

CEPT 

dB 

dBm 

DUT 

EIRP 

EIRPSD 

ETSI 

EU 

FSPL 

IQ 

LNA 

OFDM 

OTA 

PF 

PHL 

PHR 

PSD 

RTLS 

SAC 

SD 

SE 

SFD 

SRD 

Band Width 

Calibration Factor 

Conférence  européenne  des  administrations  des  postes  et  des 
télécommunications 

deciBel 

deciBel milliwatt 

Device Under Test 

Effective Isotropic Radiated Power 

Effective Isotropic Radiated Power Spectral Density 

European Telecommunications Standards Institute 

European Union 

Free Space Path Loss 

in-phase (I) and quadrature (Q) components 

Low Noise Amplifier 

Orthogonal Frequency Division Multiplex 

Over The Air 

Payload Field 

Physical layer Header 

Physical layer Header  

Power Spectral Density 

Real Time Location System 

Shielded Anechoic Chamber 

Spectral Density 

System Engineering 

Start of Frame Delimiter 

Short Range Devices 

SRdoc 

System Reference document 

25 

 
TDOA 

TRP 

Time Direction Of Arrival 

Total Radiated Power 

TRPSD or TRPSD 

Total Radiated Power Spectral Density 

Universal Serial Bus 

USB 

UWB 

Ultra Wide Band 

26 

 
 
 
 
List of figures 

Figure 1: Over The Air (OTA) measurement set up in the Shielded Anechoic Chamber (SAC) in full 
anechoic configuration. ...................................................................................................................................................... 5 

Figure 2: Measurement setup ........................................................................................................................................... 6 

Figure 3: Coordinate system associated with the DUT ............................................................................................... 7 

Figure 4: Typical setup for a combined-axes system as shown in Appendix A of the CTIA test plan [4]. ...... 7 

Figure 5: Screen shot of the terminal interface. ........................................................................................................... 9 

Figure 6: Amplitude of UWB signal versus time. ........................................................................................................ 10 

Figure 7: Amplitude of UWB signal during one frame. .............................................................................................. 10 

Figure 8 Amplitude of preamble pulses. ...................................................................................................................... 10 

Figure 9: Spectrum analyser screen shot showing spectrum trace and result of Total Channel Power 
calculation. ............................................................................................................................................................................ 13 

Figure 10: Normal orientation .......................................................................................................................................... 14 

Figure 11: Reverse orientation ......................................................................................................................................... 14 

Figure 12: Comparison of radiation patterns with Normal (blue) and Reverse (red) orientations. ............... 17 

Figure 13: Example of 3D radiation pattern .................................................................................................................. 18 

Figure 14: Example of measured radiation pattern .................................................................................................... 19 

Figure 15: Result of TRPSD measurement versus frequency ................................................................................... 20 

Figure 16: Graphical results of the measurements of EIRP (a), TRP (b), EIRPSD (c) and TRPSD (d) .................. 21 

27 

 
 
List of tables  

Table 1: List of equipment used for the test. ................................................................................................................... 8 

Table 2: Calibration parameters ...................................................................................................................................... 11 

Table 3: Spectrum analyser parameter ......................................................................................................................... 12 

Table 4: Results of the comparison ................................................................................................................................. 13 

Table 5: Effect of the orientation of the DUT transmitting in channel 5 and measured at 1m. .......................... 16 

Table 6: Effect of the orientation of the DUT transmitting in channel 9 and measured at 1m ........................... 16 

Table 7: Effect of orientation DUT transmitting in channel 5 and measured at 3m ............................................. 16 

Table 8: Effect of orientation DUT transmitting in channel 9 and measured at 3m ............................................ 16 

Table 9: Measurement results ......................................................................................................................................... 20 

28 

 
 
 
 
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