Electromagnetic Tools for Precise Ceramic Radome and ...webistem.com/ursi-f2015/output_directory/cd1/data/... · Electromagnetic Tools for Precise Ceramic Radome and Antenna Characterization

Electromagnetic Tools for Precise Ceramic Radome

and Antenna Characterization

Cynthia Junqueira*, Mario A. R. Canto**, Ediana Gambin*, Daniela Ronsó Lima*, Diovana de Moura Silva*,

Maurício Weber B. da Silva*, Gustavo R. Silvério*, Francisco C. L. de Melo*, Francisco Piorino Neto*, João M.

Kruszynski de Assis*, Marcelo B. Perotoni***, Marcelo Antonio Santos da Silva ****, Antonio Sérgio B. Sombra****

*Institute of Aeronautics and Space, IAE, Brazil {[email protected], [email protected],

[email protected], [email protected], [email protected], [email protected],

franciscofclm, franciscofpn, [email protected]}

**Industrial Fostering and Coordination Institute, IFI, Brazil, {[email protected]}

***Federal University of ABC, UFABC, Brazil{[email protected]}

****Federal University of Ceará, LOCEM, UFC, Brazil {[email protected], [email protected]}

Résumé Les applications aérospatiales requièrent l'emploi de matériaux supportant des ambiances extrêmes et les céramiques

sont un des candidats possibles. Ici le focus porte sur la caractérisation par des méthodes électromagnétiques

d'échantillons de radome réalisés en céramique. Cette contribution décrit la méthodologie de développement d'une

antenne de transpondeur en bande C recouverte d'un radome en céramique et destiné à un vol spatial. La céramique

retenue est de type aluminium-silicate (Mullite) pour laquelle trois compositions différentes sont analysées et les tests

standards accomplis. L'évaluation électromagnétique des échantillons (permittivité) a été effectuée avec des méthodes

non-destructives telles que Hakki-Colleman ou de type espace-libre. Un ensemble radome-antenne en bande C a été

conçu en technologie microstrip et employant une céramique Mullite d'épaisseur 5 mm, le prototype a été construit puis

évalué au laboratoire. Enfin, des mesures effectuées dans une chambre anéchoïde ont indiqué un excellent accord entre

simulations et résultats pratiques.

Mots-clefs: méthodes en électromagnétisme, radome céramique, méthodes non destructives, antenne.

Abstract Aerospace applications demand materials that support critical environmental conditions and ceramics are one of the

candidates. Here, the focus is the application of electromagnetic methods to precisely characterize ceramic radome

samples. This work describes a steady methodology in development of a C band transponder antenna covered with

ceramic radome for flight applications. The chosen ceramic was the aluminum silicate (Mullite) and three different

compositions were analyzed and the ceramic standard tests were accomplished. Electromagnetic samples evaluation

(electrical permittivity) was performed with the application of non destructive methods as Hakki-Colleman and Free-

Space. A C band set radome-antenna was designed with microstrip technology and employing a Mullite ceramic with 5

mm thickness, the prototype was build and evaluated at the laboratory. Finally, measurements in anechoic chamber

indicates excellent conformance between the simulations and practical results.

Index Terms: electromagnetic methods, ceramic radome, nondestructive methods, antenna.

Introduction

In aerospace applications, ceramic radomes play an important role and deserve special attention. Aerospace

applications demand materials that support critical environmental conditions and ceramics are one of the best candidates

due to their characteristics. This kind of component works together with a communications system and contributes

decisively for the resultant array pattern, so its proper characterization is very important.

In this scenario, it is important to have a holistic view over all the parameters involved in the project, because,

altogether with the material electromagnetic characterization, it is necessary that the used materials follow the

aerodynamic, structural, environmental and mechanical constraints.

The chosen ceramic was the aluminum silicate (Mullite) [1-2] mainly due to the low specific mass, good resistance

to thermal shock and low dielectric loss properties. The development was based in three different compositions and

sintering temperatures.

The designed Mullite material was checked by X-ray diffraction. During the samples development several tests

were performed: Vickers hardness, bulk density, shrinkage rate and fracture toughness. The micro structural

characterization was done by electron microscopy scanning (SEM). The best observed results for density and formation

of the Mullite phase were presented for samples sintered at 1650°C.

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Regarding the electromagnetic evaluation, measurements using the Hakki-Coleman and Free-Space methods were

performed. Both are of non-destructive type and establish a complete understanding of the samples behavior during the

design process. Additionally they can be done at the current laboratory installations. The first one is based on the theory

of dielectric resonators and is well known in the literature [3-5]. The dielectric permittivity was obtained using an in-

house software based on the Kobayashi & Katoth [6] methodology.

The Free Space method, on the other hand, performs the characterization of planar material samples positioned

between a transmitter source and a receiver antenna [7], [8]. Associated to the instrumentation setup is the Thru-Reflect-

Line (TRL) calibration [9] and the Nicolson Ross Weiss (NRW) method [10]. For the electric permittivity computation,

a code was developed and validated against measurements [11]. Current laboratory installations allow the measurement

with the Ground-Reflect-Line (GRL) calibration method together with Keysight tools [12] and a Line-Reflect-Line

(LRL) calibration method using Anritsu vector network analyzer [13].

Here, the main analyzed problem is the application of electromagnetic methods to precisely characterize developed

ceramic radome samples. A methodology for the development of an aerospace C band transponder antenna covered

with ceramic radome is also presented. This developed laboratory will be also applied to characterize different others

planar materials, dielectric or magnetic. This paper is organized in five sections. Mullite material and tests results of the methodology used in its

development are briefly discussed in section 1. Section 2 has the electromagnetic evaluation analyzed in detail. In section 3 are presented the main measurements results of the characterization methods and the developed prototype. Finally, concluding remarks are given in section 4.

1. Mullite

Mullite (3Al2O3.2SiO2) is a rare natural mineral. Being the only stable intermediate phase in the Alumina-Silica

(Al2O3-SiO2) system at atmospheric pressure, it is one of the most important ceramic materials. It is a phase of the

binary diagram Alumina-Silica whose mass corresponds to 71.8% of Al2O3 and 28.2% of SiO2. Mullite presents low

specific mass and excellent physical and mechanical properties at high temperatures, good shock response and fracture

resistance, thermal stability, low thermal conductivity and dielectric constant. Due to this, this material may have

optical and electronic device applications [14, 15].

The development was based on three different compositions and sintering temperatures. Mass percentages of

material for each composition are displayed at Table I.

Percentages (%) Row Material

Composition I Composition II Composition III

Caulim 53 50 0

Alumina CT3000 42 40 69

Fumed Silica 0 0 26

Potassium feldspar 0 5 0

Water 5 5 5

Table I Material Composition

The samples were conformed by uniaxial pressure with pressure between 40MPa and 60MPa using mechanical

steel molds as showed in Fig. 1. The size of the samples was optimized for the Hakki-Coleman method electromagnetic

test.

Fig. 1. Mechanical steel mold

Sintering was performed in a rate of 10°C/min and 1 hour of heat treatment. It was studied the evolution of the

Mullita phase formation in the compositions, as a function of the variation of temperature (in a range of 1000°C and

1650°C). The porous, specific mass and water absorption were measured by the Archimedes technique. Results indicate

that compositions I, II and III have values of porosity and water absorption close to zero and density close to the

theoretical value (3.17g/cm3 ) with the increase of the temperature.

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We also observed that the pressure used in the compactation process will result in changes of the sample physical

properties. The test was performed varying the pressure from 40 MPa to 60 MPa. During the samples development

several tests were performed. The Vickers hardness was measured with five indentations in different sample regions. As

was expected, the Vickers hardness (HV) increases with the sample sintering temperature (T). Results are synthesized

on Table II.

HV (GPa)

T (ºC) Composition I Composition II

1600 13 9

1650 15 10

Table II Vickers hardness

The thermal shock was performed with a large range of temperature variations. For the temperature variations (∆T)

larger than 400°C it was observed smaller resistance (σ) of the samples in the analyses. For the composition II, samples

sintered at 1650°C shows resistance values in table III.

∆T Test 200ºC 400ºC 600ºC 800ºC 1000ºC

Weigth(N) 233.5 115.5 75.5 70.5 59.0

σ (MPa) 76.9 39.0 25.5 23.8 19.7

Table III Resistance (σ) with thermal shock

The Mullite was checked by X-ray diffraction. During the samples development several tests were performed:

Vickers hadness, bulk density, shringage rate and fracture toughness. The micro structural characterization was done by

electron microscropt scanning (SEM). The best results for density and formation of Mullite phase was presented for

samples sintered at 1650°C.

After the tests, the composition III was discontinued and the best samples reaching 96% of the theoretical density.

The feldspar into the composition seems to promote needle-shape grains. As the sintered temperatures increase, the

physical and mechanical properties of the sample become better and more attractive to be applied as a radome material.

In this context the Mullite, in composition I and II will be the candidates to be characterized as will be described in

the following sections. Fig. 2 shows Mullite cylindrical samples and planar plate build in the development phase.

Fig. 2. Mullite samples

2. Electromagnetic Evaluation

Related with the electromagnetic evaluation, it is possible to perform tests in Hakki-Coleman and Free-Space

methods. Both are non destructive and establishes a complete understand of the samples during the design process and

can be done at laboratory installations.

2.1. Hakki-Coleman Method

This method is based on the theory of dielectric resonators [3-5]. Several configurations were developed for

the Hakki and Coleman setup, and also studied by Courtney [5] and Kobayashi [6]. Hakki and Coleman analyzed the

TE0nl modes not considering the air gap effects between the conductive plates. In the work of Cohn and Kelly [16] the

dielectric constant measurements using the TE011 mode were discussed added to a calculation proposal where the air

gap was taken in account. Courtney in [5] discusses the Hakki and Coleman technique studying a radial setup for more

flexibility in the sample size and frequency range.

The dielectric characteristics measurements in the microwave range done with this methodology consists

basically in a cylindrical sample positioned between two copper plates. This configuration allowed the propagation of


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both TM and TE modes. The TE011 mode generally is the most easily identifiable. The schematic and experimental

setup can be visualized in Fig. 3. The resonator is excited by a vector network analyzer in a transmission mode. The

maximum values indicate the frequencies where the resonance occurs. Larger peaks mean higher losses indicating a

smaller quality factor. Generally, for cylindrical resonators with diameter/height ratios (D/H) close to one, the first

resonant peak is associated with the HEM111 mode and the second resonant peak with the TE011 mode. The TE011 mode

is used for the measurements because its propagations are mainly inside the sample but it is evanescent out of the

sample. Also, with TE011 mode we have only the azimuthal component of the electrical field and the error associated

with gaps between the copper plate and the sample can be negligible [17]. In this way, the second resonant peak is

considered for the dielectric constant and loss calculations by Kobayashi & Katoth [6] methodology. Fig. 4 illustrates

the results of transmission measurement.

Fig. 3. The schematic and experimental setup

Fig. 4. Transmission measurements results

The Hakki-Coleman method and associate software validation was performed together with the LOCEM –

Laboratory of Telecommunications and Materials Science and Engineering from Federal University of Ceará in Brazil

[18] where the validation process, tabulated electrical properties materials as (PTFE) Teflon, Alumina 99% and

polypropylene (PP) samples were measured in both laboratories. The LOCEM employs a Courtney resonator from

Damaskos Inc. [19]. During the period of validation of Mullite developed and produced by Materials Department

(AMR) at Institute of Aeronautics and Space (IAE), also the complete lot of samples were measured at IAE and verified

at LOCEM. In this way, together with the results of tests as described in section I, the best set of samples were

established.

2.2. Free-Space Method

The Free-space method characterizes planar material samples positioned between a transmitter source and a

receiver [7] as shown in Fig 5. Associated to it is applied the Thru-Reflect-Line (TRL) calibration [9] and the Nicolson

Ross Weiss (NRW) method [10].

Fig.5. Schematic diagram of a test setup [7]


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The free space methods may present systematic errors, mainly due to the mismatch between the antennas and the

propagation medium of the waves until the reference planes defined by the two surfaces of the sample. As indicated on the literature [7], to obtain measurements results with quality, some requirements need to be observed as curvatures and imperfections in the faces of the sample and metal plate used as a ground plane. They need to have parallel faces positioned to the planes of the antennas apertures.

The TLR calibration procedure [9] is used to correctly measure the S parameters together with an in- house developed and validated software [20]. After data calibration, electric permittivity is calculated by another algorithm, such as the NRW method [21]. Fig. 6 shows a snapshot of the in house software screen for TLR calibration and NRW calculations.

Fig. 6. Snapshot of the software screen

The Nicolson-Ross-Weir method (NRW) [2], [3] is based on the phenomenon of reflection and transmission on the

material whose characteristics are to be determined. These phenomena occur due to the difference between the complex

permittivity and the complex permeability of the two environments involved (inside and outside the material). The

complete step by step procedure was done by the research group to overcome some obstacles the method understanding.

It is presented in [21].

TLR calibration and NRW procedure by software implemented at the laboratory were performed with collaboration

with the Signature work group from Department of Reconnaissance and Security/Microwave and Radar Institute, from

the German Aerospace Center (DLR) [22]. For the TRL software validation, as can be observed in [20], a sample of

glass was used. This sample calibration was done in two ways, via vector network analyzer (VNA) Anritsu 37269A

embedded software at DLR facilities and via software developed in the laboratory. The frequency range of the

experiment was from 26 to 40 GHz.

The NRW software validation was performed in X band range (8.5 GHz to 12.5 GHz), with materials with tabulated

electrical properties, such as air, glass, FR4, acrylic glass, polyethylene [23] and Rogers RO3210 [24]. This frequency

band was chosen due to the laboratory VNA range limitation.

It was observed conformity between the responses of the software of both institutes, as well as the tabulated values

[24]. This consistency of the obtained results indicates acceptable reliability of the developed software.

As a complementary tool, the laboratory installations were complemented with development of a setup that allows

measurement with the Ground-Reflect-Line (GRL) calibration method [25] together with Keysight VNA and embedded

software [12]. The GRL method allows dielectric and magnetic materials characterization.

Another method of calibration also was performed in the laboratory; the so called Line-Reflect-Line (LRL) [26]

calibration provides an improved error compensation capability when measurements in waveguides, microstrip or

coaxial lines. Instead of using short, open and load patterns, the LRL calibration method uses the information of the

reflector ground plane and about the two distances involved: between transmitter antenna and reflector ground plane

(Line 1) and between the reflector ground plane and receiver antenna (Line 2).

The difference in length between Line 1 and Line 2 creates a set of measurements for the minimization of systematic

errors. The complete calibration consists in two transmission lines, reflection and isolation measurements. The

correction of error in this case is done by a software and using a VNA with temporal option. Equipments from

companies as Anritsu [13] and Rohde-Schwarz [27] are prepared for this kind of calibration and errors correction. In the

laboratory an Anritsu VNA complete our park of equipments. Using the calibrated data, material permittivity or

permeability can be computed with the NRW software.


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3. The Prototype: Results and Analysis

The radome-antenna prototype was analyzed using the developed facilities in the laboratory. A set of radome

samples were built and characterized. The available methods were evaluated in the laboratory and structural and

electromagnetic simulations were performed. The prototype was built, measured and analyzed.

3.1. Hakki-Coleman Measurements

Using the Hakki-Coleman method the electrical permittivity from Mullite samples was characterized. Fig. 7

illustrate one of transmission S parameter measurement with VNA and the values to be considered at the calculations of

dielectric constant (εr) and tangent loss (tanδ).

In general, a wave propagating in a dielectric medium undergoes losses, and the permittivity of the material can no

longer be represented by a real value. These losses can be attributed to a number of causes, including conduction and

relaxation phenomena in the dielectric and in impurities, molecular resonances, and molecular structure [28-30]. Loss

tangent (tanδ) is commonly used to characterize the loss at micro and millimeter wavelengths, even though the losses

may be due to other reasons than conduction. In general, ε’ and ε’’ are functions of frequency, although in many

applications they may be considered to be constant over a limited frequency band of interest [31-34]. The dispersive

dielectric properties can also depend on temperature.

These samples were arranged in sets of Mullite compositions and sintering temperatures. Table IV shows dielectric

constant and loss results from the compositions discussed in section I. The resonant frequency (Fr) is dependent of the

sample size, and for all samples sets were considered the ratio D/H equal to 2. The measurements at room temperature

are made in the TE011 mode at a single frequency dictated by dielectric constant and the size of the cylindrical sample

from as low as about 1GHz and up to 20GHz due to the laboratory VNA up frequency restriction.

Fig. 7. Transmission S parameter measurement from vector network analyzer

T (ºC) Composition εr tanδ Fr (GHz)

I 6,41 0,0038 11,0943 1600

II 6,34 0,0045 10,7775

I 6,23 0,0071 10,7730 1650

II 5,89 0,0036 11,5415

Table IV Dielectric constant and loss characterization by de Hakki-Coleman method

For a radome-antenna simulation and construction was chosen the Mullite composition sample whose dielectric

constant and loss were in accordance with the Mullite data available in the literature, antenna substrate availability and

the Mullite samples was considered to be reproducible. In this case, composition II with dielectric constant of 5.89 and

loss of 0.0036 were chosen for the electromagnetic simulations.

3.2 Free-Space Measurements

The complete setup for the measurements, the so called bi-static arch for free space measurements was installed at

IFI laboratories inside a semi-anechoic chamber and is showed at Fig. 8. It allows control for the antennas position,

incident angles and sample fixture. The IFI measurement setup is conditioned to measure in the band of frequency of

available conical lens horn antennas, between 4 GHz and 6 GHz. The sample dimensions are related with the antenna

focal area and a good choice ratio is around 2.5. Fig. 9 shows measurements done using TRL/LRL method, Anritsu

VNA and lens corrected conical horn antenna (RA4540-5) from Rozendal Associates [35].


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Fig. 8. Bi-static arch for free space measurements

Fig. 9. TRL/LRL method measurements with Anritsu VNA.

For the correct verification of the setup calibration, before the sample measure, for the required frequency band,

two standards are checked. In our case, the air (sample fixture empty) and a PTFE (teflon) plate were considered.

Figures 10 to 13 shows the results using a GRL method applied together with Keysight VNA and software.

Fig. 10. Permittivity – real part (ε’) - Air


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Fig. 11. Permittivity – Imaginary part (ε’’) - Air

Fig. 12. Permittivity – real part (ε’) – PTFE-Teflon

Fig. 13. Permittivity – Imaginary part (ε’’) – PTFE-Teflon

3.3. Structural Simulations

After measured the electrical permittivity and loss from several Mullite samples, structural simulations by finite

element method [36] were performed for a planar plate radome. These simulations give support for the materials and

mechanical specialists, aiding in decisions aspects as material composition, radome shape and thickness. Moreover,

they allow a pre-visualization of the structural integrity of the set radome-antenna when different forces and

environmental conditions are applied.


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Typical specifications for radome materials are related to each application and usually take into account

aerodynamic effects, wind load, differential values of pressure, space heating and kinetic erosion due to dust, rain or

other destructive impacts as stones or birds, as is the case for aircraft radomes. In this work the object of study will be

applied to the specific thermal and forces operating in the region of attachment of the radar transponder microstrip

antenna into the low orbit atmospheric Reentry Satellite (SARA), being developed by Institute of Aeronautics and

Space (IAE) [37].

The microstrip antenna substrate with dimensions of 34 mm x 36 mm will be protected by the Mullite radome and

will be located in the rear of the SARA module (http://www.iae.cta.br/site/page/view/pt.sara.html), subject to a single

flight at a predetermined period. Fig. 14 displays the forces model for simulations.

Fig. 14. Forces Model (N)

The assembly antenna-radome was analyzed at room temperature. It was fixed by 304 stainless steel screws in a

small rectangular depression in the SARA body. Using the software MSC Patran / Nastran [36], the model uses shell

elements and CQUAD4 topology with the minimum possible CTRIA3 elements [12]. As related in literature [4] and

according IAE internal reports [37], these resultant forces can occur in all SARA axes as briefly illustrated in Fig. 15.

The device will be subject to gravitational and aerodynamic loads.

Fig. 15. Resultant Forces

Table V shows the properties for the case study where it can be seen that the simulation provided a minimum

thickness equal to 4.6 mm. In red it is highlighted the minimum thickness to be considered for the radome material in

the simulated set.

Material Properties Mullite

Thickeness (mm) 2.7 3 4 4.6

Runoff simulated voltage (MPa) 330 261 132 91.7

Displacement (mm) 9.42E-2 7.08E-2 3.33E-2 2.34E-2

Strength at Yield (MPa) 90 90 90 90

Strength at Break (MPa) 150 150 150 150

Modulus of Elasticity (GPa) 145 145 145 145

Dielectric Permittivity (e') 6.2 6.2 6.2 6.2

Tangent of Loss 0.005 0.005 0.005 0.005

Table V Mullite properties


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Fig. 16 shows the loads at central and peripheral zone for a 4.6 mm radome thickness. Peripheral regions have no

directly loads applied, but are impacted as proximity to the side. Fig. 17 shows the behavior of the yield stress with the

change in thickness to the radome structure.

Fig. 16. Mullite loads in radome 4.6 mm thickness (MPa)

Fig. 17. Yield Stress

3.4. Electromagnetic Simulations

Together with the previous results, a C band radome-antenna assembly was designed using microstrip technology

and employing a Mullite radome with 5 mm thickness. The thickness of radome was chosen bigger then the minimum

appointed in the structural simulations only for the simplicity and to allow the use a pre-existent mold and surface

grinding set possibility. The design was analyzed with CST MWS [38] where the permittivity data collected by

experimental tests with Hakki-Coleman method was considered.

For the microstrip antenna the chosen substrate was Arlon GX-0300-55-11, thickness of 0.762mm, dielectric

constant 2.55, los tangent of 0.0022 and laminate with 1oz. cupper [39].

The Fig. 18 shows a lateral view of the CST antenna model. The prototype has rectangular geometry, coaxial probe

feed and linear polarization. The theoretical resonant frequency was chosen 5.7 GHz and the minimum bandwidth of

100 MHz, considering S11 magnitude ≤ -10dB.

Fig. 18. Microstrip antenna and radome CST model - lateral view


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The simulated results from input impedance and radiation pattern are showed in Fig. 19 and 20. Fig 19 shows the

reflection coefficient magnitude versus frequency. The magnitude of S11 is -26.45 dB at the resonant frequency and

bandwidth around 180 MHz.

Fig. 19. Reflection coefficient magnitude (S11) (dB)

Figure 20 illustrate the directivity on the plane ϕ=90°, where can be observed at the main lobe direction a small

displacement of ∆θ = 6° and amplitude value of 5.3 dBi. In the plane ϕ=0° the directivity shows values of 5.2 dBi,

where the displacement of ∆θ = 1°. These small differences are considered negligible and the antenna was built with the

patch geometric values from the simulations. Fig. 21 shows the radome-antenna assembly in the IFI anechoic chamber.

Fig. 20. Farfield directivity - ϕ=90°

Fig. 21. Radome-antenna assembly


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The measurements results were performed at the IFI anechoic chamber and are shown in fig. 22 to 25. The input

reflection coefficient magnitude can be observed at fig. 22, where the excellent impedance matching at frequency band

from 5.6 GHz to 5.9 GHz is highlighted. The experimental resonant frequency was 5.79 GHz and presents a S11 of -

33dB. The measured Smith chart diagram is displayed at Fig. 23.

Fig. 22. Amplitude do coeficiente de reflexão de entrada

Fig. 23. Smith chart diagram

The radiation pattern and gain measurements were performed considering the frequency of 5.7 GHz. The fig. 24

and 25 shows the measurement results in comparison with the radiation pattern of a standard horn for a rectangular and

polar representation at the plane ϕ=90° respectively. The measured gain was 5.26 dBi and the results indicates excellent

conformance between the simulations and practical results.

Fig. 24. Rectangular radiation pattern representation - Gain (dBi) versus Azimuth angle (θ °)


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Fig. 25. Polar radiation pattern and Gain representation (dBi) versus Azimuth angle (θ °)

The displacement values between theoretical and experimental results can be explained by the radome-antenna

assembly and due to the quality in the surface grinding. These differences will be the starting point for future

investigations and process improvements.

4. Conclusions

The focus of this work is the application of electromagnetic methods to precisely characterize ceramic radome

samples. Additionally, a methodology for a radome-covered C-band transponder antenna design is presented, for

aerospace application. The chosen ceramic was Mullite, after its optimum composition and sintering temperature were

determined.

A study of several methods for permittivity and loss characterization was performed. Advantages and

disadvantages of the employed methods were covered, using Matlab and C#.

The measurements with the Hakki-Coleman method at IAE/IFI were validated at LOCEM/UFC. The development

of free-space method, together with TRL calibration was extensively studied and the validation was done together with

the DLR research group. In addition, GRL and LRL methods were also applied in the laboratory with the standard

materials for testing purposes.

The electromagnetic analysis of the prototype radome-antenna was done with the CST simulation software using

microstrip technology. Structural simulations were performed at the Mullite radome-antenna in C band for application

in SARA low orbit satellite to aid the optimum radome thickness parameter.

The complete experimental electromagnetic characterization was performed, involving the radiation pattern, gain

and impedance. These results agree satisfactorily with the CST simulations results.

Additionally to the technical results achieved during the project development, a free-space materials measurement

facility was developed and deployed at IFI facilities. This laboratory is pioneer in Brazil and complements IFI existent

facilities such as anechoic and reverberant chamber. It enables the characterization of different planar dielectric,

magnetic or absorbers materials. Finally, the project in its multidisciplinary approach provides integration and

qualification of human resources between different research groups in Brazil.

Acknowledgment

The work presented in this paper has been supported by National Counsel of Technological and Scientific

Development (CNPq Project no. 559991/2010-0). Special thanks to Stefan Thurner for providing experimental data on

free space measurements at DLR. The authors want to acknowledge the collaboration of Sgt. Bruno Duarte, João Paulo

Hasmann and Cláudio Nogueira from IAE/DCTA.

References

[1]J.F. Shackelford and R.H. Doremus (eds.), “Ceramic and Glass Materials: Structure, Properties and Processing”,

Springer 2008, 202p.

[2]H. Schneider and S. Komarneni (eds.), “Mullite” , 2005, 509p.

[3]B.W. Hakki and P.D. Coleman, “A dielectric resonator method of measuring inductive capacities in the millimeter

range”, IRE Trans. Microwave Theory Tech., vol. MTT-8, pp. 402-410, July 1960.

[4]G. Kent, “Dielectric resonances for measuring dielectric properties”, Microwave Journal, 31 (10), pp.99-114, 1988.

[5]W. E. Courtney, “Analysis and evaluation of a method of measuring the complex permittivity and permeability of

microwave insulators”, IEEE Transactions on Microwave Theory and Techniques, 18 (8), 476-485, 1970.


129

[6] Y. Kobayashi, M. Katoh, “Microwave Measurement of Dielectric Properties of Low-Loss Materials by the

Dielectric Rod Resonator Method”; IEEE Transactions on Microwave Theory and Techniques, Vol. MTT-33, (7), July,

1985.

[7] L. F. Chen, et. al., “Microwave Electronics: Measurements and Materials Characterization”, John Wiley & Sons,

West Sussex, England, 2004, 252p.

[8] A. Priou, Materiaux Composites en Electromagnetisme Materiaux composites en electromagnetisme, Ed.

Techniques Ingénieur, 2009.

[9]G. F. Engen, C. A. Hoer, “Thru-reflect-line: An improved technique for calibrating the dual six-port automatic

network analyzer", IEEE Transactions on Microwave Theory and Techniques, vol. 27, No. 12, 987-993, December

1979.

[10] A. N. Vicente, G. M. Dip, C. C. M. Junqueira, “The Step by Step Development of NRW Method”, In: Proceddings

of Microwave & Optoelectronics Conference (IMOC) 2011.

[11] Rocha, L.; Junqueira, C.; Gambin, E. ; Vicente, A.N.; Culhaoglu, A. E. ; Kemptner, E. . “A Free Space

Measurement Approach for Dielectric Material Characterization. In: Proceedings of IEEE-MTTS International

Microwave and Optoelectronics Conference, Rio de Janeiro, SBMO/IEEE MTT-S, 2013.

[12] Keysight Technologies, http:// www.keysight.com.

[13] Anritsu, http://www.anritsu.com/

[14] D. G. L. Cavalcante, L. N. L. Santana, S. J. G. Lima, G. A. Neves, H. L. Lira. “Identificação de mulita através da

caracterização microestrutural de composições formados pela sinterização de resíduo de caulim, ball clay e alumina” In:

17º CBECIMat, Congresso Brasileiro de Engenharia e Ciência dos Materiais, 15 a 19 de Novembro de 2006, Foz do

Iguaçu, PR, Brasil, 2006.

[15] M. I. Brasileiro, D. H. S. Oliveira, M. F. Oliveira, G. A. Neves, K. F. S. Ribeiro, L. N. L. Santana, “Estudo da

obtenção de mulita por meio de interações entre o resíduo de caulim e ball-clay sinterizados, e alumina, em um processo

termicamente ativado” In: 17º CBECIMat, Congresso Brasileiro de Engenharia e Ciência dos Materiais, 15 a 19 de

Novembro de 2006, Foz do Iguaçu, PR, Brasil, 2006.

[16] S. B. Cohn e K. C. Kelly, “Microwave Measurement of High-Dielectric- Constant Materials,” IEEE Transactions

on Microwave Theory and Techniques, vol. 14, n. 9, pp. 406-410, september 1966.

[17] D. kajfez, W. P. Wheless Jr e R. T. Ward, “influence of an airgap on the measurement of dieletric constant by a

parallel-plate dieletric ressonator,” IEE Proceedings, vol. 133, n. 4, pp. 253-258, August 1986.

[18] LOCEM, Laboratory of Telecommunications and Materials Science and Engineering, Federal University of Ceara,

UFC, Brazil.

[19] Damaskus Inc. Material Measurement Solution, http://www.damaskosinc.com.

[20] L. ROCHA, C. Junqueira, E. Gambin, A. N. Vicente, A. E. Culhaoglu, E. Kemptner, “A Free Space Measurement

Approach for Dielectric Material Characterization” In: IEEE-MTTS International Microwave and Optoelectronics

Conference, 2013, Rio de Janeiro. 2013 SBMO/IEEE MTT-S, 2013.

[21] A. N. Vicente, G. M. Dip, C. Junqueira, “The Step by Step NRW Method”. In: IEEE International Microwave

Conference, IMOC 2011, 2011, Natal. Anais do IEEE International Microwave Conference, IMOC 2011, 2011.

[22] German Aerospace Center, Microwaves and Radar institute, DLR,

http://www.dlr.de/hr/en/desktopdefault.aspx/tabid-2434/3770_read-32519

[23] Dielectric constants, http://www.rfcafe.com/references/electrical/dielectric-constants-strengths.htm

[24] Rogers Corporation, RO3200 Series Circuit Materials, Revised 0975 071712 Publication 92-109,

www.rogerscorp.com.

[25] Technical Overview, “Agilent 85071E Materials Measurement Software”, Agilent literature number 5988-9472EN

.

[26] Anritsu Application Note 11410-00492.pdf, “LRL/LRM calibration: theory and methodology”, MS4640A Vector

Network Analyzer, VectorStar VNA

[27] Rohde & Schwarz Inc., http://www.rohde-schwarz.com/en/home_48230.html

[28] E.S. Kim, W. Choi, “Effect of phase transition on the microwavedielectric properties of BiNbO4”. J. Eur. Ceram.

Soc. 26, 1761–1776, 2006.

[29] D. Zhou, H. Wang, X. Yao, “Microwave dielectric properties and co-firing of BiNbO4 ceramics with CuO

substitution”. Mater. Chem. Phys. 104, 397–402, 2007.

[30] N. Wang, M.-Y.Zhao, Z.-W.Yin, W. Li, “Effects of complex substitution of La and Nd for Bi on the microwave

dielectric properties of BiNbO4” Ceramics Mater. Res. Bull. 39, 439–448, 2004.

[31] C. Yeh, F.I. Shimabukuro, “The essence of dielectric waveguides” Springer, New York, 2008.

[32] M. N. Afsar, K. J. Button, “Millimeter-wave dielectric measurement of materials”, in Proceedings of IEEE 73,

131-153,1985.

[33] J.W. Lamb, Miscellaneous data on materials for millimetre and submillimetre optics. Int. J. Infrared MM Waves

17, 1997,1996.

[34] J.R. Birch, J.D. Dromey, J. Lisurf, “The optical constants of some common low loss polymers between 4 and 40

cm-1”. Infrared Phys. 21, 225, 1981.

[35] Rozendal Associates Inc. http://www.rozendalassociates.com.

[36] MSC Software Patran-Nastran, 2004, www.mscsoftware.com.


130

[37] IAE-ASE-RT-2006 Análise modal teórica do VS40/SARA sub-orbital para cálculo de cargas em vôo. Institute of

Aeronautics and Space (IAE) - Internal Report, 2006.

[38] CST Computer Simulation Technology, 2014, www.cst.com.

[39]Arlon Cuclad 250GX series cross-plied woven PTFE/Fiberglass, http://www.arlon-med.com/Microwave-Materials/.

.


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