In antenna measurement, well-established procedures are consolidated to determine the associated measurement uncertainty for a given antenna and measurements scenario [1-2]. Similar criteria for establishing uncertainties in numerical modeling of the same antenna are still to be established. In this paper, we investigate the achievable agreement between antenna measurement and simulation when external error sources are minimized. The test object, is a reflector fed by a wideband dual ridge horn (SR40-A and SH4000) manufactured by MVG. This highly stable reference antenna has been selected to minimize uncertainty related to finite manufacturing and material parameter accuracy. Two frequencies, 10.7GHz and 18GHz have been selected for detailed investigation. The antenna has been measured by several measurement facilities (spherical, cylindrical and planar near field ranges) across Europe in the ? ? ? ? ? ? ? ? activity. The purpose of this intercomparison campaign is the comparison of the different antenna measurement facilities, throughout Europe, considering measurement procedures and uncertainty estimates. The antenna has been simulated using a full CAD model, in step compatible format and using different numerical methods from different software vendor

Sierra Castañer, Manuel

Foged, Lars Jacob

Saporetti, M. A.

Jørgensen, E.

Voigt, T.

Tallini, D.

Orefice, M.

Giordanengo, Boris

Dassano, G.

Böttcher, M.

Wien, A.

Serna, J.M.

Pérez de Diego, D.

Calvano, F.

In this work, we propose the implementation of a part-of-speech tagging system using recurrent neural networks. For that purpose, initially we study the theoretical fundamentals of that kind of neural networks. Next, we propose three different architectures in order to disambiguate ambiguous words. Finally, we achieve a system able to disambiguate with a 93.5% total accuracy and with 83.2% accuracy on ambiguous words with the section of Wall Street Journal that belongs to the Penn Treebank corpus

Valero Antón, Francisco de Borja

Repositorio Institucional de la Universidad de Alicante

Neural part-of-speech tagging

Servicio de Coordinación de Bibliotecas de la Universidad Politécnica de Madrid

Comparison of Reflector Antenna  
Measurements and Simulations  
M. Sierra Castañer  
Grupo de Radiación. ETSI Telecomunicación,Universidad 
Politécnica de Madrid (UPM) 
Madrid, Spain 
mscastaner@gr.ssr.upm.es  
L.J. Foged, M.A.Saporetti,  
Microwave Vision Italy (MVI) 
Pomezia, Italy  
(lars.foged, maria.saporetti)@microwavevision.com 
E. Jørgensen  
TICRA  
Copenhagen K, Denmark  
ej@ticra.com  
T. Voigt  
Altair (FEKO)  
Böblingen, Germany  
voigt@altair.de 
D. Tallini  
CST AG  
Darmstadt, Germany  
Davide.Tallini@cst.com 
M.Orefice, G. Giordanengo, G. Dassano 
Antenna and EMC Lab (LACE)  
Politecnico di Torino, Torino, Italy 
(mario.orefice,giorgio.giordanengo,
gianluca.dassano)@polito.it  
M. Böttcher, A. Wien 
IMST GmbH 
Kamp-Lintfort,Germany 
 (boettcher, wien )@imst.de 
J. M. Serna  
Technological Development Center of Yebes (CDT) 
Yebes,Guadalajara - Spain  
jm.serna@oan.es 
D. Pérez de Diego  
Centro de Alta Tecnología y Homologación -CATECHOM- 
Universidad de Alcalá,Spain 
diego.perezd@uah.es 
F. Calvano 
ANSYS  Italia Srl,  
Viale Luca Gaurico, 9/11, 00143 Roma, Italy 
flavio.calvano@ansys.com 
Abstract? In antenna measurement, well-established procedures 
are consolidated to determine the associated measurement 
uncertainty for a given antenna and measurements scenario [1-2]. 
Similar criteria for establishing uncertainties in numerical 
modeling of the same antenna are still to be established. In this 
paper, we investigate the achievable agreement between antenna 
measurement and simulation when external error sources are
minimized. The test object, is a reflector fed by a wideband dual
ridge horn (SR40-A and SH4000) manufactured by MVG. This 
highly stable reference antenna has been selected to minimize 
uncertainty related to finite manufacturing and material 
parameter accuracy. Two frequencies, 10.7GHz and 18GHz have 
been selected for detailed investigation. The antenna has been 
measured by several measurement facilities (spherical, 
cylindrical and planar near field ranges)  across Europe  in the
?????? ??? ???? ??????? ??? ? ?????????? ??????????? ??????????
activity.  The purpose of this intercomparison campaign is the 
comparison of the different antenna measurement facilities, 
throughout Europe, considering measurement procedures and
uncertainty estimates. The antenna has been simulated using a 
full CAD model, in step compatible format and using different 
numerical methods from different software vendors [3-7]. 
I. INTRODUCTION
The achievable agreement between antenna measurement 
and simulation has already been investigated in [8], using a
reflector fed by a wideband dual ridge horn (SR40-A and 
SH4000) by MVG, which has been measured in two antenna 
measurements systems and simulated with four different 
numerical tools. The study carried here is a further analysis 
which  involves an higher number of: 
? measurements: seven measurements have been 
performed in six different measurement facilities 
across Europe (in the frame of the EurAAP/WG5  
???????????????????????????????????????),   
? simulations: five simulations have been performed 
with tools from five software vendors. 
The objective of the paper is to show the agreement 
between different measurement setups, between different 
software tools, and, more important, the agreement between 
simulation and measurements to check the limitation of the 
simulation tools. 
368
II. TEST OBJECT
The SR40-A and SH4000 antenna is shown in Fig. 1. The 
SR40-A is an offset parabolic reflector, precision machined 
from a single block of aluminum. The circular interface with 
precision holes allows the user to center the antenna with very 
high accuracy. The alignment accuracy is determined to within 
±0.01°. The SH4000 wide band Dual Ridge Horn is a highly 
stable reference antenna precision fitted to the mounting  
bracket of the reflector. 
            
Figure 1.  Reflector SR 40-A fed by SH4000 Dual Ridge 
Horn: Antenna during measurement (left); CAD file for 
simulation (right). 
III. SIMULATION CAMPAIGN 
Simulations have been performed at 10.7GHz and 18GHz, 
considering the nominal dimensions of the feed and reflector 
and ignoring finite manufacturing and material parameter 
tolerances. The electrical conductivity of aluminum was 
assumed to be 3.56 107 S/m in the simulation of ohmic losses. 
The complete CAD file of the antenna was provided to each of 
the participants involved. Each participant was responsible for 
generating a suitable mesh and the numerical stability of their 
solution. The information collected from simulations is 
reported in Table I. 
TABLE I.  SIMULATION DATA
Peak Directivity 10.7, 18 GHz 
Directivity 
patterns 
Phi:from 0° to 135°(45° step) 
Theta: from -180° to 180° (1° and 
0.1° step) 
Return Loss 10.7, 18 GHz 
Ohmic Losses 10.7, 18 GHz 
Each field solver has used the simulation method 
considered the most efficient for reflector design. The list of 
numerical methods is shown in Table II, while Fig.2 to 6 show 
the currents, the fields and the mesh grid resulting from each 
numerical tool. 
TABLE II.  NUMERICAL METHODS USED FOR  THE SIMULATIONS 
SIMULTATION TOOL NUMERICAL METHOD 
GRASP Higher-order Multi-level Fast Multipole 
ANSYS Hybrid FEBI (enhancement to the FEM solver) 
FEKO Multi-level Fast Multipole 
CST Time Domain Solver (based on the Finite Integration Technique ) 
EMPIRE Finite Difference Time Domain 
Figure 2.  GRASP- currents induced on the antenna and 
mesh grid @18GHz. Reflector SR 40-and SH4000 fed 
(left), Close-up of the feed (right). 
Figure 3.  HFSS simulated surface current density 
Js@10.7GHz (left) and 18GHz (right) Reflector SR 40-
A with SH4000 Dual Ridge Horn.  
Figure 4.  FEKO - currents induced on the antenna 
structure and applied mesh @18GHz on the Reflector 
SR 40-A with SH4000 Dual Ridge Horn. Currents (left); 
Close-up of the feed (right). 
369
Figure 5.  CST- Simulated E-field @10.7GHz (left) and 
@18GHz (right). Reflector SR 40-A with SH4000 Dual 
Ridge Horn. 
Figure 6.  EMPIRE simulated Near Field@10.7GHz 
IV. MEASUREMENT CAMPAIGN 
The measurement uncertainty or error estimate for a given 
antenna, using a given measurement range, remains an 
approximation, until this estimate has been successfully 
validated against other measurements. Such validation can be 
achieved by means of facility intercomparison campaigns, 
which provides the formal opportunity for the participants to 
validate and document their achieved measurement accuracy 
and procedures from comparison with other facilities. Facility-
comparison campaigns are an important on-going activity in 
the frame of the EurAPP working group on antennas 
measurements and the SR40-A and SH4000 antenna is part of a 
currently ongoing measurement facility comparison campaign.  
The information collected from measurements is reported in 
Table III. 
TABLE III.  MEASUREMENT DATA
Peak Directivity 10.7, 12.6, 14.5,18, 19, 20, 28, 29, 30, 31 ,33, 38  GHz 
Directivity 
patterns 
Phi:from 0° to 135°(45° step) 
Theta: from -180° to 180° (1° 
steps) 
Return Loss 10.7-38 GHz 
Ohmic Losses 10.7-38 GHz 
Uncertainty 
Budget 10.7-38 GHz 
The list of the facilities, involved in the EurAAP 
intercomparison campaign and whose data have been used for 
the results reported below, is shown in Table IV while Fig.7 
shows the geographical location. 
TABLE IV.  ANTENNA MEASUREMENT SYSTEMS 
FACILITY RANGE
Universidad Politécnica de 
Madrid (UPM) -2 measurements  Spherical Near Field
MVG SG64 (Paris) Spherical Near Field 
University of Alcalà Spherical Near Field 
Politecnico di Torino Spherical Near Field 
Astronomic Observatory of 
Yebes Planar Near Field
IMST Cylindrical Near Field 
Figure 7.  European location of some facilities involved in 
the Reflector SR40+SH4000 campaign. 
V. RESULTS COMPARISON
A reference pattern has been computed both for simulations 
and for measurements. 
 The simulation reference pattern has been obtained as the 
simple mean of all the simulated radiation patterns, using 
amplitude data only.  
The measurement reference patterns can be calculated as 
the simple mean or weighted mean of each measured data point 
where the weights are proportional to the estimated uncertainty. 
In [9], different data processing procedures  have been 
investigated to derive reference patterns with increased 
confidence level based on measurements in different facilities. 
Anyway, research is still ongoing to define the best way of 
defining the reference pattern through a proper combination of 
measurements and weights. For this activity, the simple mean 
of the radiation patterns, using amplitude data only, has been 
used to define the measurement reference pattern. 
In the following, comparisons including the peak 
directivity, patterns, equivalent error level and losses are 
reported.   
A. Peak Directivity Comparison 
The peak directivity values are reported for measurement 
and  simulation references in Table V. The table confirms the 
very good agreement between measurements and simulations.  
370
TABLE V.  MEASURED AND SIMULATED PEAK DIRECTIVITY 
Peak Directivity [dBi] 
Frequency Measured Simulated 
10.7 GHz 31.15 31.10
18 GHz 35.50 35.60
B. Pattern Comparison 
The Ludwig III [10] co-polar and cross-polar components 
[Ludwig III of the measurement and simulation reference 
patterns at 2 cuts, phi=0° and  90°, @ 10.7GHz and 18GHz are 
reported. The agreement can also be evaluated as a single 
value. The pattern correlation or equivalent noise level is 
reported in the following paragraph. 
Figure 8.  Measurement and simulation reference 
directivity patterns @10.7GHz, phi=0°. 
Figure 9.  Measurement and simulation reference 
directivity patterns @10.7GHz, phi=90°. 
Figure 10.  Measurement and simulation reference 
directivity patterns @18GHz, phi=0°. 
Figure 11.  Measurement and simulation reference 
directivity patterns @18GHz, phi=90°. 
C. Pattern Correlation/Equivalen Noise Level 
The visible pattern agreement is confirmed by computing 
the pattern correlation or equivalent noise level: 
?
?
?
?
?
?
?
?
?
???
?
???
? ??
boresightref
xpcorefxpco
Dir
DirDir
StdDevEqNoise
,
,_,log*20 ? ????
where Dirco,xp is the directivity (or gain) of the copolar (or 
crosspolar) component , Dirref_co,,xp is the directivity (or gain) of 
the reference copolar (or crosspolar) component and 
Dirref,boresight is the directivity (or Gain) of the reference copolar 
component at the boresight. 
 Correlation between measurement and simulation 
reference has been computed in a ±45° conical angle for both 
polarizations as reported in Table VI.
TABLE VI.  EQUIVALENT NOISE LEVEL@10.7 AND 18 GHZ
Equivalent Noise Level  [dB] @10.7 GHz  
Phi cut CO CX
0° -49.37 -50.49 
Equivalent Noise Level [dB]@18 GHz 
Phi cut CO CX
0° -49.77 -50.23 
D. Dissipation Loss Comparison 
The measurement and simulation reference dissipation
losses are reported in Table VII. Measured losses are obtained 
as the difference between the IEEE Gain and the Directivity, 
therefore the accuracy is related to the gain accuracy of the 
measurement facilities.  
It seems that simulations underestimate the losses. A
plausible explanation is connector losses, not included in the 
simulation scenarios and the uncertainty of the aluminum 
electrical conductivity considered in the simulations. The 
vendor sheet value has been used in the simulation with no 
experimental verification. 
371
TABLE VII.  DISSIPATION LOSS
Dissipation Loss [dB]  
Frequency Measured Simulated 
10.7 GHz -0.49 -0.09 
18 GHz -0.68 -0.17 
E. Matching / Return Loss Comparison 
The measurement and simulation reference return loss 
values are reported in Table VIII. At 18 GHz, in particular, 
some differences between simulations and measurements are 
visible. These can be explained from the differences in 
matching condition in the simulation scenario and the actual 
antenna. Simulations have been performed considering a 
discrete excitation port of the SH4000 with definitions 
depending on the numerical tool. Measurements are referred to 
????????????????????????????????For measurements, the return 
loss is available as a curve over the frequency band, which is 
more meaningful for the comparison and it is shown in Figure 
12. 
TABLE VIII.  RETURN LOSS
Return Loss [dB]  
Frequency Measured Simulated 
10.7 GHz -12.89 -11.91 
18 GHz -16.84 -14.71
Figure 12.  Return Loss as a curve over the frequency for 
measurements results (MVG, Yebes, IMST, UNIAlcalà, 
PoliTo,UMP1 and UPM 2) and 2 discrete points as 
reference for simulations. 
VI. CONCLUSIONS
The achievable agreement between antenna measurement 
and numerical simulation has been investigated using many 
measurements and many simulations. The experiment has been 
designed to minimize error sources not pertinent to 
simulation/measurement. The agreement between simulation 
and measurements is deemed excellent, considering 
uncertainties due to simulation, measurement and 
manufacturing. The level of correlation between measurements 
and simulation achieved here are better than what has been 
found in recent facility comparisons campaigns. Very good
agreement has been achieved for performance parameters such 
as peak directivity, pattern, and good agreement for gain 
contributions such as dissipation loss and matching. 
REFERENCES
[1] ANSI/IEEE Std 149-?????????????????????????????????????????????
[2] IEEE Std 1720? 2012, ?Recommended Practice for Near? Field 
Antenna Measurements?.
[3] ???????????????????????????????????????????????
[4] www.feko.info, Altair Engineering GmbH, Germany 
[5] www.ansys.com/Products/Simulation+Technology/Electronics/Signal+I
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??? ????????? ??? ????????????????????? ???? ??????????? ??? ??????????
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???????? ??? ??? ??????? ????????? ??? ???????? ?????????? ??????????
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372


Comparison of reflector antenna measurements and simulations

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Comparison of reflector antenna measurements and simulations

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