ETSI TR 103 086 V1.1.1 (2013-03)

Technical Report
Electromagnetic compatibility
and Radio spectrum Matters (ERM);
Short Range Devices (SRD);
Conformance test procedure for the exterior limit tests in
EN 302065-3 UWB applications in the ground based vehicle
environment
2 ETSI TR 103 086 V1.1.1 (2013-03)

Reference
DTR/ERM-TGUWB-021
Keywords
measurement uncertainty, radio measurements,
SRD, UWB
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3 ETSI TR 103 086 V1.1.1 (2013-03)
Contents
Intellectual Property Rights . 5
Foreword . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definitions, symbols and abbreviations . 7
3.1 Definitions . 7
3.2 Symbols . 7
3.3 Abbreviations . 7
4 Summary Of ECC Consideration . 8
5 Fundamental Channel Measurements . 8
5.1 Calibration and Test Measurement . 9
5.1.1 Measurement Setup. 9
5.1.2 Antenna Pattern Analysis . 10
5.1.3 Reference Antenna Pattern . 11
5.1.4 Maximum Measureable Distance . 12
5.2 Car shielding/car influence measurement . 14
5.2.1 Car shielding and fading analysis: TX antenna in the middle of the car . 14
5.2.2 Measurements at 3 m using UWB transmission power (-41,3 dBm) . 19
5.2.3 In-Car measurements position on the roof of the car . 19
5.3 Surface and Application Specific Location Measurements . 21
5.3.1 TX antenna mounted below the car on the exhaust pipe. 21
5.3.2 TX antenna mounted on the side mirror . 23
5.3.3 TX Antenna on the wheel in the fender . 25
5.3.4 Conclusions. 26
6 Conclusions and Recommendations from the Measurements . 27
7 Test Procedure . 27
8 Conclusions . 29
Annex A: Measurement Hardware . 30
A.1 Measurement Hardware . 30
A.2 Link Budget . 30
Annex B: Spherical Scan . 31
B.1 Spherical scan with automatic test antenna placement . 31
B.1.1 Calibrated setup . 32
B.1.2 Substitution method . 32
B.2 Spherical scan with rotating device . 33
B.2.1 Calibrated setup . 33
B.2.2 Substitution method . 34
Annex C: Tire Related Applications . . 35
C.1 Introduction . 35
C.2 Procedure to establish the shielding characterization of the tire . 35
C.3 Main influencing elements of a road vehicle . 45
C.4 Relevant area for the case of the UWB device inside tire . 53
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4 ETSI TR 103 086 V1.1.1 (2013-03)
C.5 Measurement in a relevant area for the case of the UWB device inside tire or inside the fender
space. . 54
C.6 Summary . 62
History . 63

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5 ETSI TR 103 086 V1.1.1 (2013-03)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Electromagnetic compatibility and Radio
spectrum Matters (ERM).
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6 ETSI TR 103 086 V1.1.1 (2013-03)
1 Scope
The present document specifies a measurement procedure for the exterior limit for road and rail vehicle applications
defined in ECC DEC (06)04 [i.2] from 2011. The procedure is intended to be used in the upcoming standard
EN 302 065-3 [i.8].
The measurement procedure has been developed based on an extensive measurement campaign with a full car inside a
semi-anechoic chamber, in which the radio channel from the inside to the outside, from the transmission of the surface,
from below the car and from the tyre are studied in detail.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI EN 302 065 V1.2.1 (2010-10): "Electromagnetic compatibility and Radio spectrum Matters
(ERM); Short Range Devices (SRD) using Ultra Wide Band technology (UWB) for
communications purposes; Harmonized EN covering the essential requirements of article 3.2 of
the R&TTE Directive".
[i.2] ECC Decision (06) 04 of 24 March 2006 amended 15 December 2011 on the harmonised
conditions for devices using Ultra-Wideband (UWB) technology in bands below 10,6 GHz.
[i.3] F. Berens, H. Dunger, S. Czamecki, T. Bock, R. Reuter, S. Zeisberg, J. Weber and J.F. Guasch:
"UWB car attenuation measurements", 16th IST Mobile and Wireless Communications Summit,
2007.
[i.4] R. Zetik, A. P. Garcia Ariza, R. Thomä, W. Kotterman:"Application-specific MIMO-UWB
channel measurements and parameter extraction: Integrated Project - EUWB", Deliverable
D3.1.2b, 2009.
[i.5] ETSI TS 102 883 (V1.1.1): "Electromagnetic compatibility and Radio spectrum Matters (ERM);
Short Range Devices (SRD) using Ultra Wide Band (UWB); Measurement Techniques".
[i.6] ECC TG3: "UWB Screening Attenuation of Cars", TG3#16-21R0, European Commission JRC,
Ispra, Italy, 2006.
[i.7] M. Cheikh, J. David, J.-G. Tartarin, S. Kessler, A. Morin:"RF source characterization of Tire
Pressure Monitoring System"; 2nd European Wireless Technology Conference, 2009 (EuWIT
2009), Rome, Page(s): 176 - 179.
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7 ETSI TR 103 086 V1.1.1 (2013-03)
[i.8] ETSI EN 302 065-3: "Electromagnetic compatibility and Radio spectrum Matters (ERM) Short
Range Devices (SRD) using Ultra Wide Band technology (UWB) for communications purposes;
Harmonized EN covering the essential requirements of article 3.2 of the R&TTE Directive Part 3:
Requirements for UWB devices for road and rail vehicles".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
equivalent isotropically radiated power (e.i.r.p.): product of the power supplied to the antenna and the antenna gain
in a given direction relative to an isotropic antenna (absolute or isotropic gain) (RR 1.161)
3.2 Symbols
For the purposes of the present document, the following symbols apply:
d Distance
Θ Elevation angle
δ Loss factor
Dielectric constant
f Frequency
Receive antenna reflection coefficient
Transmit antenna reflection coefficient
Receive antenna gain
Transmit antenna gain
Wavelength
Receive cable losses
Transmitter cable losses
� Azimuth angle
Receive power
Signal generator output power
Conductivity
Direction of the received electrical field
Direction of the transmitted electrical field
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
BW BandWidth
CW Continuous Wave
DAA Detect And Avoid
DIT Device Inside the Tire
DUT Device Under Test
e.i.r.p. equivalent isotropically radiated power
EM ElectroMagnetic
GTX Gain Transmitter
LACE Laboratory of Antennas and Electromagnetic Compatibility
LAN Local Area Network
LDC Low Duty Cycle
LNA Low Noise Amplifier
LOS Line Of Sight
ML MessLabor
NF Noise Figure
PEC Perfect Electric Conductor
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PSD Power Spectral Density
RAM Radar Absorbing Material
RF Radio Frequency
RMS Root Mean Square
RX Receiver / Receive
SNR Signal to Noise Ratio
TPC Transmit Power Control
TX Transmitter / Transmit
UWB Ultra WideBand
4 Summary Of ECC Consideration
The considerations defined in ECC/DEC/(06)04 [i.2] allow, besides general cases, the usage of Ultra Wideband (UWB)
devices installed in road and rail vehicles, where special limits apply for the bands 3,1 GHz to 4,8 GHz, 6 GHz to
8,5 GHz and 8,5 GHz to 9 GHz if mitigation techniques are implemented.
Operation is permitted with a maximum mean e.i.r.p. spectral density (PSD ) of -41,3 dBm/MHz and a maximum
mean
peak e.i.r.p. (PSD ) of 0 dBm defined in 50 MHz if:
peak
• within the bands 3,1 GHz to 4,8 GHz and 6 GHz to 8,5 GHz Low Duty Cycle (LDC) and an exterior limit
(PSD ) of -53,3 dBm/MHz are implemented; or
ext
• within the bands 3,1 GHz to 4,8 GHz and 8,5 GHz to 9 GHz Detect And Avoid (DAA), Transmit Power
Control (TPC) and an exterior limit of -53,3 dBm/MHz are implemented; or
• within the band 6 GHz to 8,5 GHz Transmit Power Control (TPC) and an exterior limit of -53,3 dBm/MHz are
implemented.
The exterior limit is valid above 0 degree, whereas the reference plane for the 0 degree is the sensor mounting height.
Figure 1 shows the principle of these considerations.

Figure 1: Principle of the considerations
NOTE: The exterior limit refers to the maximum mean e.i.r.p. spectral density measured outside the vehicle and
every local maximum is below the limits.
5 Fundamental Channel Measurements
This clause presents channel measurements, which are used to clarify fundamental issues, i.e. to evaluate the maximum
measureable distance and to study the influence of the car. Based on these results the measurement concept for the
exterior car limit in EN 302 065-3 [i.8] is developed.
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9 ETSI TR 103 086 V1.1.1 (2013-03)
The measurement campaign was performed at a semi-anechoic chamber at the Messlabor (ML) Kolberg of the
Bundesnetzagentur in Germany. First test and calibration measurements were performed without a car in an anechoic
chamber. As the semi-anechoic chamber shows a measurement uncertainty of ± 6 dB, the measurements are compared
to full anechoic chamber measurement from a previous measurement campaign at BOSCH. This shows the influence of
the chamber.
Next the channel was characterized from the inside to the outside of the car and from application relevant locations on
its surface.
5.1 Calibration and Test Measurement
5.1.1 Measurement Setup
The measurement setup of the calibration measurements is shown in the next figures. A microwave generator produces
a continuous wave (CW) at frequencies between 3 GHz and 5 GHz with a step size of 500 MHz and from 6 GHz to
9 GHz with a step size of 1 GHz. The signal is transmitted by a Vivaldi antenna and is received at 10 meters distance by
a calibrated log periodic receiver (RX) antenna. The signal is amplified by a low noise amplifier (LNA) and is measured
with a spectrum analyzer. The settings of the spectrum analyzer are shown in table 1. A detailed description of the
measurement hardware can be found in table A.1.

Figure 2: Antenna Pattern Calibration Measurement Setup

(a) Setup (b) Vivaldi TX Antenna (c) Log-periodic RX antenna
Figure 3: Antenna Pattern Calibration Measurement Setup: Photos
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Table 1: Spectrum analyzer settings according to EN 302 065 [i.1]
Parameter Value
Start Frequency 2 GHz
Stop Frequency 10 GHz
Resolution BW 1 MHz
Video BW 3 MHz
Detector Mode RMS
Averaging time 1ms (per point on spectrum analyser scan)

The transmitter (TX) antenna is continuously rotated about the vertical axis and the received power is calculated back to
the transmitted e.i.r.p. The calibration measurements were performed only for the vertical polarization corresponding to
the polarization of the TX antenna.
5.1.2 Antenna Pattern Analysis
As the transmitter antenna gain in the transmit path are unknown and the transmit e.i.r.p. has to be known, they were
determined by calibration measurements. This is done by calculation of the e.i.r.p. from the received power
using Friis law where f is the frequency and d is the distance. The Friis equations in dB is given by:

where P is the output power of the signal generator, and are the TX and RX cable losses, and
out
are the TX and RX antenna gains, and is the LNA gain. As e.i.r.p. is given by:

where � is the azimuth and Θ is the elevation angle, it follows that:
.
where λ is the wavelength. All parameters are known except can be calculated straight forward by:
.
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The measured antenna gain including the cable losses are shown in figure 4.

Figure 4: TX antenna pattern (measured)
We can see that the antenna gain between -60° and 75° is approx. constant, but the gain is frequency dependent and
achieves values between -5 dB and +9 dB. The peak at 170° occurs from the measurement cable, this can be observed if
the plot is compared to the reference antenna pattern (see figure 5).
5.1.3 Reference Antenna Pattern
The real antenna pattern was previously measured in a full anechoic chamber at BOSCH. Figure 5 shows the frequency
dependency of the Vivaldi antenna. The nominal gain at azimuth angle 0° and the maximum gain are shown in table 2.
Furthermore the TX cable losses are shown for the calculation of e.i.r.p.
A comparison of figures 4 and 5 shows that the patterns are very similar, but due to measurement uncertainties (mainly
from diffraction and reflections) the maximum gain can differ up to 4 dB for specific frequencies.
The real antenna gain is used for the calculation of the e.i.r.p. values.
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12 ETSI TR 103 086 V1.1.1 (2013-03)

Figure 5: TX antenna pattern (real – measured in full anechoic chamber)
Table 2: Nominal and maximum gain of the antenna pattern
Frequency [GHz] Nominal angle Nominal gain Max. gain angle Max. gain [dBi] TX Cable
[deg] [dBi] [deg] losses
2 0 1,7 45 2,2 0,57
3 0 -0,9 -81 3,6 0,66
3,5 0 -0,45* 2,1* 0,74
4 0 0 78 0,5 0,79
4,5 0 1,5* 1,8* 0,82
5 0 3 -21 3,0 0,86
6 0 4,3 -9 4,4 0,95
7 0 7,1 -39 7,8 1,02
8 0 6,6 -6 6,7 1,1
9 0 7,8 -18 7,9 1,19
NOTE: * Linear interpolated.
For all measurements where the transmit power is set to a specific e.i.r.p. level, the output level of the signal generator
P is given by
out
and is set to the max. antenna gain (f) of table 2.
5.1.4 Maximum Measureable Distance
The necessary SNR for an accurate measurement is approximately 10 dB. Thus, we can calculate the maximum
measureable distance for UWB transmission levels, if typical high performance measurement equipment is used.
The measurements were done at a distance of 10 m with and P was reduced from 0 dBm to -50 dBm in
out
10 dB steps.
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10 10
0 4,000000000 GHz
-1,998 dBm
-10 -10
-20 -20
-30 -30
4,000000000 GHz
-41,615 dBm
-40 -40
-50 -50
-60
-60
-70 -70
-80
-80
3800  3850  3900  3950  4000  4050  4100  4150  4200 3800  3850  3900  3950  4000  4050  4100  4150  4200
Frequenz in MHz
Frequenz in MHz
(a) (b)
Figure 6: Measured TX power for SNR analysis
Figure 6 shows that an e.i.r.p. of -41,3 dBm is measureable at a distance of 10 m with sufficient SNR, but the exterior
limit of -53,3 dBm/MHz is below the noise floor. Therefore a maximum measureable distance can be calculated where
the attenuation is 12 dB less using Free space equation. A maximum measurable distance of 2,5 m is obtained. As the
car is very close if the distance is only 2,5 m, we decided to go to 3 m which decreases the SNR by 1,5 dB, but it is the
minimum practical distance.
Note, the noise floor is -52 dBm/MHz, because the received noise power is calculated for e.i.r.p. Thus the correction is
done accounting for the free space loss, cable losses, antenna gains, and the LNA gain.
Note, the measured SNRs correspond perfectly with the expected ones from the link budget in table A.2. A direct
comparison can be done if 6 dB will be subtracted from the 2 GHz value to obtain the corresponding 4 GHz value.
The next measurements were performed at 3 m and e.i.r.p.=-53,3 dBm. The results are summarized in table 3.
Table 3: Measured SNR at 3m using e.i.r.p. = -53,3 dBm
f [GHz] G [dB] P [dB] e.i.r.p[dB] SNR [dB]
TX
out
3,0 -0,9 -52,3 -53,4 11,0
3,5 -0,3 -53,0 -53,9 9,0
4,0 -0,6 -52,7 -53,3 8,0
4,5 1,7 -55,0 -52,8 8,0
5,0 2,9 -56,2 -52,5 7,0
6,0 3,1 -56,4 -51,0 4,2
We can see that the expected SNR matches very well the measured one (SNR = 8,5 dB at 4 GHz). Obviously it is not
possible to measure -53,3 dBm at the higher frequencies with the current high performance setup. Thus a more sensitive
measurement setup has to be chosen for the higher frequencies, which could be achieved e.g. by using a higher RX
antenna gain (> 7 dBi) or a lower noise figure of the LNA (< 2,6 dB).
For the measurement at 10 GHz additional 10,5 dB gain are needed in comparison to 3 GHz. Horn antenna gains are
available on the market up to 14 dBi to16 dBi.
Conclusions:
The current measurement equipment with a measurement antenna with 7 dB gain and an LNA with 28 dBgain/2,6 dB
noise figure, was sufficiet to measure signals at 3 m with e.i.r.p.=-41,3 dBm/MHz. But the exterior limit of
-53,3 dBm/MHz was not measureable at the higher frequencies, thus higher antenna gains or lower NFs are necessary.
The proposed parameters for the measurement equipment are shown in table 4.
ETSI
Pegel in dBm
Pegel in dBm
14 ETSI TR 103 086 V1.1.1 (2013-03)
Table 4: Recommended Hardware
Device Parameter Value
LNA NF < 2 dB
LNA Gain > 30 dB
RX Horn Antenna Gain (10 GHz) > 16 dB
RX Horn Antenna Gain (8 GHz) > 14 dB
RX Horn Antenna Gain (6 GHz) > 12,5 dB
RX Horn Antenna Gain (2 GHz to 5 GHz) > 10 dB
Cables Shielding > 60 dB
Cable Losses Take losses into account for total gain
calculations
NOTE: The noise floor of the combined equipment should be at least 6 dB but 10 dB would be optimal.

5.2 Car shielding/car influence measurement
The goal of these measurements is to study the impact of the car on the measured/calculated transmit power (e.i.r.p.).
First, the TX antenna is placed in the middle of the car and in the centre of the rotating plate. Then the car is rotated
by 360° and the received power is measured at 10 m. The measurement is repeated for several RX antenna heights (see
figure 7). This allows the detection of the peak power spots. The measurements were repeated for several distances and
a comparison of the measured powers allows a fading analysis. The minimum distance is evaluated at which the fading
does not significantly influence the estimated transmit power. Next, the SNR (at 3 m) will be evaluated for a transmit
power of -41,3 dBm/MHz. This is necessary to show which peaks are measureable for e.i.r.p. = -41,3 dBm/MHz.
Finally, a second position of the antenna is analysed, in which the antenna is placed on the roof above the rear seat.
5.2.1 Car shielding and fading analysis: TX antenna in the middle of the
car
The measurement setup is shown in table 7. The sensor was placed close to the middle of the rotation axis.

(a) Measurement setup
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(b) TX antenna (height 1 m) (c) TX antenna

(d) RX antenna at 3 m and 1,45 m height (8,5°) (e) RX antenna at 10 m and 1 m height (0°)
Figure 7: Car Shielding and Fading Measurement Setup
The measurement parameters are shown in table 5 and the settings of the spectrum analyzer are shown in table 1.
Table 5: Shielding and Fading Analysis: Measurement Parameters
Measurement e.i.r.p. Distance Frequency
Elevation angle Θ
1 0 dBm 3 m 0°; 8,5°; 16,7° 3; 3,5; 4; 4,5; 5; 6
2 0 dBm 4,5 m 0°; 8,5°; 16,7° 3; 3,5; 4; 4,5; 5; 6
3 0 dBm 7 m 0°; 8,5°; 16,7° 3; 3,5; 4; 4,5; 5; 6
4 0 dBm 10 m 0°; 8,5°; 16,7° 3; 3,5; 4; 4,5; 5; 6

Figure 8 shows that for this car no shielding is given, because the signals can penetrate the windows with nearly no
attenuation. This could be completely different if the car has metalized windows, where significant higher shielding can
be expected [i.3] and [i.6]. Several peaks occur with gains of 0 dB meaning no shielding and maximum values of 3 dB
occur. The horizontal polarization is significantly lower than the vertical polarization. Only a few peak values can be
observed with maximum values of -3 dB.
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The measurements of the fading analysis are shown in figure 9. Therefore the measurements where repeated for
different distances. An angle of Θ = 8,5° was chosen because the previous measurements showed there the highest
peaks. Obviously good correlation of the antenna pattern is given, but the peak values are slightly different in value and
angle. Table 6 summarizes the peak values for analysis. The deviations Δ (10 m) and Δ (10 m) are the maximum and
max mean
the mean deviation with respect to 10 m for all frequencies. That assumes that 10 m leads to the most accurate
measurements. We can see that the deviations at all distances are within 3 dB and are acceptable accurate. Furthermore
we can see that always higher values of the mean and peak powers are observed at 3 m in comparison to 10 m. Thus a
measurement at 3 m is on the safe side from the interference point of few.
Table 6: Mean and peak e.i.r.p. with respect to distance
Mean e.i.r.p. [dBm] Angle max. e.i.r.p. [deg] Max. e.i.r.p. [dBm]
3 m 4,5 m 7 m 10 m 3 m 4,5 m 7 m 10 m 3 m 4,5 m 7 m 10 m
3 GHz -6,3 -7,3 -7,1 -7,6 -176 -12 -24 -25 1,2 -1,8 -0,5 -1,6
3,5GHz -4,6 -5,4 -5,4 -5,8 1 -69 -66 -71 1,8 1,2 1,1 0,1
4 GHz -4,5 -4,9 -4,8 -5,0 25 28 23 23 2,5 2,2 2,3 2,8
4,5GHz -4,6 -5,9 -5,8 -5,4 0 -24 0 -31 3,2 1,9 1,8 1,6
5 GHz -5,0 -5,4 -5,1 -5,1 -8 -5 -3 0 5,0 5,1 5,4 3,4
6 GHz -7,0 -6,9 -7,1 -7,3 -17 -3 -2 -6 2,7 0,9 2,8 1,6
Δ (10 m) 1,3 0,5 0,5 -- -- -- -- -- 2,8 1,7 2 --
max
Δ (10 m) 0,7 0,33 0,28 -- -- -- -- -- 1,5 0,76 1 --
mean
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Figure 8: TX antenna in the middle of the car: Measured e.i.r.p. (dBm/MHz)
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Figure 9: TX antenna in the middle of the car: Measured e.i.r.p.,
distance dependency of measurements
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Conclusions:
• No shielding can be expected from the inside to the outside for this car. A different situation can be expected
for e.g. metalized windows.
• The transmission patterns do not significantly vary for the different distances.
• A measurement at 3m is accurate enough and stronger peaks and more average power is measured in
comparison to the other distances. Thus a measurement at 3m is safe from interference point of view.
• If it is not possible to place the TX antenna close to the center of the rotating plate, the measurements have to
be corrected by a measurement correction procedure. (see EN 302 065-3 [i.8]).
• If a semi anechoic chamber is used, the ground between TX and RX antenna should be covered by absorber
material. This should be done at least for the area of the direct ground reflection (see figure 9).
5.2.2 Measurements at 3 m using UWB transmission power (-41,3 dBm)
The measurement parameters can be found in table 7. The angle of 8,5° was chosen, because the highest peaks were
observed at these heights in the previous clause.
Table 7: Shielding and Fading Measurements Parameters
Measurement e.i.r.p. Distance Angle Frequency
5 -41,3 dBm 3 m 8,5° 3; 4,5; 6; 7,5; 9

Figure 10: Measurement at 3 m with e.i.r.p. -41,3 dBm: Measured e.i.r.p.
We can see that the peaks are well measureable at e.i.r.p. = -41,3 dBm. The peak values of all frequencies occur in the
main transmission direction. Only at 3 GHz many peak values are observable at other angels, because the therefore the
antenna pattern is oval and has higher gain to the side (see figure 5).
5.2.3 In-Car measurements position on the roof of the car
In these measurements the TX antenna was mounted above the right rear seat under the roof (see figure 11). Again the
car was rotated by 360° and the settings of the spectrum analyzer were the same as in table 1.
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(a) TX antenna under the roof (b) RX antenna at 3m and 4m height (42°)
Figure 11: In-Car measurements RX antenna under the roof
Table 8: In-Car under the roof measurements parameters
Measurement e.i.r.p. Distance Angle Frequency
6 0 dBm 3 m [0°; 8,5°; 16,7°; 42°] 3; 3,5; 4; 4,5; 5; 6

Figure 12: TX antenna inside the car under the roof: Measured e.i.r.p.
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21 ETSI TR 103 086 V1.1.1 (2013-03)
Figure 12 shows the measurement results. The shape of the antenna pattern is not observable, thus only reflections are
detectable. A comparison to the other scenario (see figure 8) shows that the roof has a shielding between 5 dB and 10
dB. Only the signals, which could directly penetrate the window (see -90° to -180°), show low attenuation. Thus a smart
placement of the TX antenna could lead to significant shielding by the roof.
5.3 Surface and Application Specific Location Measurements
These measurements were done according to specific application relevant locations. Three scenarios have been
measured, where the TX antenna was mounted:
• Below the car on the exhaust pipe.
• On the surface of the car on the side mirror.
• On the wheel of the car in the fender.
The influence of the car has been studied.
5.3.1 TX antenna mounted below the car on the exhaust pipe
The TX antenna is mounted below the car on the exhaust pipe (see figure 11).

(a) Vertical polarized (b) Horizontal polarized (c) Horizontal polarized
Figure 13: Mounting of the TX antenna below the car
The measurement parameters are shown in table 9 and the settings of the spectrum analyzer can be found in table 1.
Table 9: Measurement parameters for TX antenna below the car
Measurement Polarization e.i.r.p. Distance Height Frequency
7 Vertical 0 dBm 10 m [1 m, 2,5 m, 4 m] 3, 4, 5, 6
8 Horizontal 0 dBm 10 m [1 m, 2,5 m, 4 m] 3, 4, 5, 6

Figure 14 shows the measurement results for the vertical polarized antenna. Obviously no antenna pattern is observable,
only strong reflections were measured due to the shielding of the car. As the ground plane was made of metal, no
attenuation occurred and the ground with the basement of the car worked as a parallel-plate waveguide. Thus high gains
of more than 5 dB can occur. On the other side, in a real scenario no metal ground plane occurs and thus lower gains
should be expected (see clause C.3). It follows that the ground in the measurement chamber should be defined for such
applications later in the harmonized standard. A comparison to the horizontal polarized antenna (see figure 15) shows
no significant difference.
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Figure 14: Vertical polarized TX antenna below the exhaust at 10 m: Measured e.i.r.p.
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Figure 15: Horizontal polarized TX antenna below the exhaust at d = 10 m: Measured e.i.r.p.
5.3.2 TX antenna mounted on the side mirror
Next, the antenna was mounted on the side mirror. This analysis shows the influence of the car if the TX antenna is
mounted on the surface of the car. The antenna mounting is shown in figure 16, in which the main transmission
direction of the antenna is given by � = 90°.

Figure 16: TX antenna on the side mirror
The measurement parameters can be found in table 10 and the settings of the spectrum analyzer can be found in table 1.
Table 10: Measurement Parameters: TX antenna on side mirror
Measurement Polarization e.i.r.p. Distance Height Frequency
9 Vertical 0 dBm 10 m [1 m, 2,5 m, 4 m] 3, 4, 5, 6

Figure 16 shows the measurement results for vertical and horizontal polarized RX antenna. The transmission pattern is
very well observable. We can see that the peaks occur in the main transmission direction. On the backside of the car no
relevant peaks are observable due to shielding.
All measurements show good correlation with the real antenna pattern (compare to figures 2 and 3) except the
measurement at 5 GHz where an untypical gain of +5 dB occurs. This can be explained by the measurement uncertainty
discussed in Section Measurements at 3 m using UWB transmission power (-41,3 dBm), because an average additional
gain of approx. +2,5 dB (main transmission direction) was measured in comparison to the real antenna pattern.
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Figure 17: TX antenna mounted on the mirror at d = 10 m: Measured e.i.r.p.
NOTE: At Θ = 16,7° the 3 GHz measurement is missing, because the RX antenna did not switch correctly to
horizontal polarization.
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5.3.3 TX Antenna on the wheel in the fender
In this scenario the antenna was mounted inside the fender. The interaction of the antenna, the fender and the wheel
needs to be studied. The antenna setup is shown in figure 18, in which the main transmission direction of the antenna is
given at � = 90°.
Figure 18: Car setup with antenna in the fender
The measurement parameters can be found in table 11 and the settings of the spectrum analyzer can be found in table 1.
Table 11: Measurement Parameters: TX antenna in the fender
Measurement Polarization e.i.r.p. Distance Height Frequency
10 Vertical 0 dBm 10 m [1 m, 2,5 m, 4 m] 3, 4, 5, 6

Figure 19 shows the measured e.i.r.p. values with vertical and horizontal orientated RX antenna. It is clearly to see that
the maximum peaks occur if the RX antenna is orientated directly to the wheel (� = 90°). Thus the measurement area
can be reduced to the area in front of the wheel instead of measuring the whole car.
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Figure 19: TX antenna mounted on the wheel at d = 10m: Measured e.i.r.p.
5.3.4 Conclusions
• We can observe that for applications where the TX antenna is mounted below the car the measurements should
not be done with a metallic ground plane, because due to wave guiding effects high gains could occur. These
gains do not occur in reality as the ground is usually not a perfect conductor.
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• If the antenna is mounted on the surface of the car, all peaks occur in the line of sight (LOS) direction of the
device. Furthermore the antenna pattern is very well observable in this area.
• If the antenna is mounted on the wheel and the fender, all peaks occur in the LOS direction to the wheel. Thus
this area is sufficient to measure, because the rest of the car does not have significant impact on the
measurement. It follows that a combination of the fender and the wheel is sufficient to measure.
• No specific gain was measured for the tire, thus it is sufficient only to measure the tire if the exterior limit is
transmitted.
6 Conclusions and Recommendations from the
Measurements
Kolberg Measurement
• No shielding of the car could be observed from the inside to the outside for this car in the Kolberg
measurements. If a manufacturer wants to transmit more than -53,3 dBm/MHz inside the car he has to ensure
that the shielding of the car is higher. Higher shielding is expected e.g. for metalized windows. The
manufacturer has to determine the parts with the lowest shielding (e.g. the windows) and has to adopt the
transmission power to it.
• The maximum measureable distance according to TS 102 883 [i.5] with sufficient SNR is 3m using high
performance measurement equipment. The measured transmission pattern correlates very well for distances
between 3 m and 10 m and the measurement tolerance is within ±6 dB. A recommendation for the
requirements of the measurement equipment is given in clause 5.1.4.
• At the usage of a semi-anechoic chamber the ground should be covered by absorbing material. This is
necessary to reduce the effect of reflections and increase the measurement accuracy.
• If the UWB device is mounted below the car, a ground plane made of metal will lead to wave guiding effects
with unrealistic high gains. This should be taken into account for the further measurement procedure in the
harmonized standard EN 302 065-3 [i.8].
• For devices mounted on the surface of the car the maximum values occur in the LOS area, where the antenna
pattern is very well observable. Therefore a complete spherical measurement around the device is not
necessary. This car shielding effect should be taken into account for further measurement procedures in
EN 302 065-3 [i.8].
• For devices mounted on the wheel or in the fender, it is observable that only parts of the car, e.g. wheel and
fender are relevant for the maximum values and so the measurement of the whole car can be reduced to a
combination it (see clause C.3).
• As no gain was measured for the tire scenario, it is sufficient to measure only the tire if only the exterior limit
is transmitted. Otherwise a combination with the tire and the significant parts (see clause C.3) has to be
measured.
7 Test Procedure
Based on the previous results the concept for the measurements of the exterior limit for EN 302 065-3 [i.8] is
developed. The structure of the measurement is shown in figure 20.
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Figure 20: Concept for the measurement procedure of the exterior limit of EN 302 065-3 [i.8]
1) Full spherical scan to obtain transmission pattern or common measurement method according to
TS 102 883 [i.5].
2) The horizontal reference plane is the height of the sensor and all measurements have to be performed above 0°
elevation to this plane.
3) If the part of mounting has influence on the transmission pattern, then the manufacturer can declare the whole
part as a device, e.g. door, mirror, bonnet, light, etc.
4) If the fixed orientation of the surface and therefore the main transmission direction can be declared by the
manufacturer.
5) Are the relevant parts of the vehicle, which are expected to influence the transmission to the outside. The
measurement setup can be reduced to the known relevant parts.
The device under test (DUT) is specifically measured for different applications and mounting locations.
If a device has a maximum mean power of less or equal than -53,3 dBm/MHz (e.i.r.p.) including the transmission
pattern, then it is only necessary to measure the device by itself. This can be done radiated or conducted according to
TS 102 883 [i.5]. If the transmission pattern of the device is not known a full spherical scan according to annex B
should be performed.
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If the maximum mean power is greater than -53,3 dBm/MHz (e.i.r.p.) and no shielding to the outside of the car occurs
or the shielding is not considered, then the device has to be measured with the relevant parts of the car, which influence
the transmission pattern. When the relevant parts are known, then the device can be measured with these only and if
applicable for a relevant area, e.g. see tire applications in annex C. These parts and the relevant area have to be declared
by the manufacturer and should be included in the measurement report.
If shielding from the inside to the outside of the car occurs, it can be taken into account if the manufacturer can
characterized the lowest shielding in all direction to the outside. An example for a measurement procedure for the
shielding characterization can be found in clause C.1 or [i.6]. If the transmit power minus the shielding is less
than -53,3 dBm/MHz the device passes, otherwise the device has to be measured with the relevant parts of the car.
If the device is mounted outside on the surface of the car and the mounting orientation is known t
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