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DIPLOMA THESIS
VECTOR ANTENNA FOR
ULTRAHIGH ENERGY COSMIC
NEUTRINO DETECTION IN THE
ANTARCTIC ICE
AYOBAMI BABATUNDE IJI
Uppsala School of Engineering
and
Department of Astronomy and Space Physics, Uppsala University, Sweden
DECEMBER 19, 2007
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This thesis work is Dedicated to:
THE MOST HIGH GOD.
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CONTENTS
Contents iii
List of Figures v
1 Introduction 1
2 Introduction to Antennas 5
2.1 Wire antennas 5
2.2 Dipole antennas 6
2.3 Half-wavelenght Dipole 8
2.4 Radiation Pattern of a Dipole Antenna 8
2.5 Antenna Polarization 10
3 Design Considerations for the Vector Antenna 11
3.1 Vector Antenna 11
3.2 Determining the Wavelength () for the Vector Antenna 11
3.3 Efficiency Analysis. 12
3.4 Radiation Efficiency of Antenna 12
3.5 Antenna Loss Resistance 14
3.6 Determining the Operation Frequency for the Vector Antenna 16
3.7 Design Considerations 17
3.8 Ultra HighEnergy Cosmic Neutrino (UHEC) Antanna 17
4 Mechanical Construction 19
4.1 Mechanical Considerations for Design 19
4.2 The Cover of the Antenna 19
4.3 The material for the Antennas 20
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CONTENTS
4.4 Mechanical Model And Drawings of the Vector Antenna 20
4.5 Geometry alignment for a 3D object 21
5 Vector Antenna performance 35
5.1 Electrical Properties of the Antenna Medium or Environment 35
5.1.1 Electromagnetic Wave in Ice 35
5.2 UHEC Antenna Amplification 35
5.3 Vector Measurements 36
5.3.1 The 3D E-field antennas 36
5.4 Vector Pulse Post-Processing 36
6 Electrical Simulation of Antenna 41
7 Conclusion 51
Bibliography 55
Bibliography 55
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LIST OF FIGURES
2.1 Current Distribution of a Vertical Electric Dipole. 6
2.2 Current Distribution of a 3D orthogonal dipole 7
3.1 Thevenin equivalent transmitting mode of antenna 13
4.1 Top model made of peek 20
4.2 Machine drawing of the top model 22
4.3 Angle formed by the orthogonal antennas with centre 23
4.4 Bottom model 24
4.5 Bottom model machine drawing 25
4.6 Vee band 26
4.7 Vee band machine drawing 27
4.8 Antenna with fittings 28
4.9 Antenna with fitting 29
4.10 Electronics circuit board. 30
4.11 complete model 31
4.12 Internal structure of complete model 32
4.13 Finished tripole antenna. Photo by T. Thrnlund 33
5.1 Circuitry of the orthogonal dipole antenna 37
5.2 Simulation of vector pulse processing. The pulse record is 64 samples
long. At 1 Gsamp/s corresponding to 64 ns. 39
6.1 Orthogonal Vector antennas total gain 42
6.2 Orthogonal vector antennas total gain 43
6.3 vector antennas total gain 44
6.4 Vertical gain 45
6.5 vertical gain orthogonal dipole 46
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LIST OF FIGURES
6.6 Horizontal gain 47
6.7 horizontal gain orthogonal dipole 48
6.8 horizontal axis total gain 3D orthogonal dipole 49
6.9 vertical axis total gain 3D orthogonal dipole 50
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1
INTRODUCTION
This project describes the design of a vector antenna for ultrahigh energy cosmic
neutrino (UHEC) detection in the Antarctic ice. Neutrinos are elementary parti-
cles that travel close to the speed of light, lack an electric charge, are able to pass
through ordinary matter almost undisturbed and are thus extremely difficult to de-
tect. Neutrinos have a minuscule, but non-zero, mass too small to be measured as
of 2007. They are usually denoted by the Greek letter (nu). Neutrinos are cre-
ated as a result of certain types of radioactive decay or nuclear reactions such as
those that take place in the sun, in nuclear reactors, or when cosmic rays hit atoms.
Neutrino was postulated in 1930 by Wolfgang Pauli,[2] 1945 Nobel Laureate in
Physics, in order to solve an energy crisis in nuclear physics. There are three types
of neutrinos: the electron neutrino e, the muon neutrino and the tau neutrino
t. These neutrinos are related with three electrically charged particles, the elec-
tron, the muon and the tau. When a neutrino interacts with matter, it can either
continue as a neutrino after the interaction (neutral current interaction) or create
the corresponding charged particle (charge current interaction). The electron neu-
trino creates an electron, the muon neutrino a muon, and the tau neutrino a tau
lepton.
Most neutrinos passing through the Earth emanate from the sun, and more than 50
trillion solar electron neutrinos pass through the human body every second. The
sun emits vast numbers of neutrinos which can pass through the earth with little
or no interaction. This leads to the statement Solar neutrinos shine down on us
during the day and shine up on us during the night". Neutrinos are produced by
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CHAPTER 1. INTRODUCTION
the decay of radioactive elements and elementary particles such as pions (pi me-
son). Unlike other particles, neutrinos are antisocial, difficult to trap in a detector.
It is the feeble interaction of neutrinos with matter that makes them uniquely valu-
able as astronomical messengers. Unlike photons or charged particles, neutrinos
can emerge from deep inside their sources and travel across the universe without
interference. They are not deflected by interstellar magnetic fields and are not
absorbed by intervening matter.
However, this same trait makes cosmic neutrinos extremely difficult to detect;
immense instruments are required to find them in sufficient numbers to trace theirorigin. There are large volumes of ice below the South Pole to watch for the
rare neutrino that crashes into an atom of ice. This collision produces a particle
dubbed a muon that emerges from the wreckage. In the ultra-transparent ice, the
muon radiates blue light that is detected by IceCubes optical sensors. The muon
preserves the direction of the original neutrino, thus pointing back to its cosmic
source. The IceCube is located at the South Pole, which is actually near the middle
of Antarctic. Antarctic is from the Greek word antarktikos which means opposite
the Arctic is generally defined as one of the coldest, windiest, highest, and driest
locations in the world. Its also one of the most fascinating.
Antarctic is the fifth largest continent at 13,720,000 km2 but has the highest av-
erage elevation because of its thick layer of ice. Centered around the South Pole,almost the entire continent is located south of the Antarctic circle.
The IceCube Neutrino Detector is a neutrino telescope currently under construc-
tion at the South Pole. Like its predecessor, the Antarctic Muon and Neutrino
Detector Array (AMANDA), IceCube is being constructed in deep Antarctic ice
by deploying thousands of spherical optical sensors (photomultiplier tubes, or
PMTs) at depths between 1,450 and 2,450 meters. The sensors are deployed on
strings of sixty modules each, into holes melted in the ice using a hot water drill.
Another of the Icecube project is the Radio Ice Cherenkov Experiment (RICE),
which consists of 18 radio receivers deployed in the ice at a depth of 100 - 300 m;presently another project known as Askaryan Underice Radio Array (AURA), has
been proposed for the next-generation radio neutrino detector for south pole. The
AURA consists of new digital radio module (DRM) which incorporate triggering
and data handling electronics.
We are developing a broadband vector antennas made of three orthogonal dipole
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antennas that will be compatible with the AURA triggering electronics and capa-
ble of obtaining full polarization coverage for detection of neutrinos in the Ice-
Cube. [1]
The main goal of the experiment is to detect neutrino in the high energy range,
spanning from 1011 eV to about 1021 eV.
The neutrinos are not detected themselves. Instead, the rare instance of a collision
between a neutrino and an atom within the ice is used to deduce the kinematical
parameters of the incoming neutrino. Current estimates predict the detection of
about one thousand such events per day in the fully constructed IceCube detector.
Due to the high density of the ice, almost all detected products of the initial colli-sion will be muons.
The experiment is most sensitive to the flux of muon neutrinos through its vol-
ume. Most of these neutrinos will come from cascades in Earths atmosphere
caused by cosmic rays, but some unknown fraction may come from astronomical
sources.
To distinguish these two sources statistically, the direction and angle of the in-
coming neutrino is estimated from its collision by-products. One can generally
say, that a neutrino coming from above down into the detector is most likely stem-
ming from an atmospheric shower, and a neutrino traveling up from below is more
likely from a different source.
The sources of those neutrinos coming up from below could be black holes,
gamma ray bursters, or supernova remnants. The data that IceCube will collect
will also contribute to our understanding of cosmic rays, supersymmetry, weakly
interacting massive particles (WIMPS), and other aspects of nuclear and particle
physics. [2]
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2
INTRODUCTION TO
ANTENNAS
An antenna is a conducting device or transducer designed to transmit or receive
radio waves which are a class of electromagnetic waves. Hence, antennas converts
radio frequency electrical currents into electromagnetic waves and vise versa. An-
tennas are used in systems such as radio and television broadcasting, point to point
radio communication, wireless lan, radar and space exploration. Antennas usually
work in air or outer space and can also be operated under water, in ice and in other
dielectric media. An ideal antenna is one that will radiate all the power deliveredto it from the transmitter in a desired direction or directions. However, In prac-
tice such ideal performances cannot be achieved but may be closely approached.
Various types of antennas are available and each type can take different forms
to achieve the desired radiation characteristics for the particular application. The
vector antenna designed used in this thesis consists of three mutually orthogonal
wire antennas oriented along the x, y, and z -axes.
2.1 Wire antennas
These are common type of antenna that are familiar to layman because they are
mostly seen every where on building automobile ships and aircrafts etc. There are
various shapes of wire antennas such as a straight wire (dipole), loop and helix
antenna. The vector antenna is a dipole antenna in 3D, orthogonally aligned in its
axes.
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CHAPTER 2. INTRODUCTION TO ANTENNAS
2.2 Dipole antennas
A dipole antenna is a linear wire positioned symmetrically at the origin of its co-
ordinate system and oriented in its axes; the dipole antenna is small with its length
and cross-sectional area very small or negligible. The antenna is centre-fed with
current and the current vanishes at the end points. [5]
Figure 2.1: Current Distribution of a Vertical Electric Dipole.
Vertical electric dipole: an antenna oriented along the z-axes above the ground
is referred to as the vertical dipole.Horizontal electric dipole: an antenna oriented along the y-axes above the ground
is referred to as the horizontal dipole.
The vector antenna as a 3D orthogonal dipole, consists of three mutually orthog-
onal dipoles and can be oriented so that one of the dipole is vertical and the other
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2.2. DIPOLE ANTENNAS
two horizontal.
Figure 2.2: Current Distribution of a 3D orthogonal dipole
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CHAPTER 2. INTRODUCTION TO ANTENNAS
2.3 Half-wavelenght Dipole
The often used antenna is the half wavelength dipole which has a radiation resis-
tance of 73 which is very close to the 5075 characteristics impedances of
the most common transmission lines. This makes the matching to the transmis-
sion line is simple, especially at resonance.
The electric far-field and magnetic field components of a half wavelength dipole
are shown in the equation below:
E jIoe
jKr
2r
cos
2cos
sin
(2.1)
H jIoejKr
2r
cos
2cos
sin
(2.2)
Also the time average radiation density and radiation intensity can be written re-
spectively as follows [5]
Wav = |Io|282r2
cos
2cos
sin
2 |Io|
2
82r2sin3 (2.3)
and
U= r2Wav = |Io|282
cos
2cos
sin
2 |Io|
2
82sin3 (2.4)
2.4 Radiation Pattern of a Dipole Antenna
The radiation pattern describes the radiation parameters as a function of space
coordinates for an antenna but usually, the power pattern is meant. It could be in
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2.4. RADIATION PATTERN OF A DIPOLE ANTENNA
the fraunhofer region (Far Field Pattern) or the Fresnel region (Near Field Pattern).
A finite length dipole antenna is subdivided into a number of infinitesimal dipoles
of length z. As the number of the subdivisions is increased each infinitesimal
dipole approaches a length dz. An infinitesimal dipole of length dz
positioned
along the z -axis at z
the electric and magnetic field components in the far field
are given as, [5]
dE j KIe(xyzejkR)4R
sindz
(2.5a)
dEr dE = dHr= dH= 0 (2.5b)
dH jKIe(x
y
zejkR)
4Rsindz
(2.5c)
where:
R rz cos for phase termsR r for amplitude
Then the Far field approximation is given by:
dE j KIe(x
y
zejkr)
4rsinejkz
cosdz
(2.6)
E=
+l/2
l/2dE= j
kejkr
4rsin
+l/2
l/2Ie
x
,y
,z
ejkzcosdz
(2.7)
where the factor outside the brackets represents the elements factor and that withthe brackets is the space factor. The elements factor depends on the type of cur-
rents and its direction of flow while the space factor is a function of the current
distribution along the source. The total field of the antenna is equal to the product
of the element and space factors.
Total field = (Element factor Space factor).
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CHAPTER 2. INTRODUCTION TO ANTENNAS
2.5 Antenna Polarization
All electromagnetic, EM, waves, traveling in free space, have an electric field
component, E, and a magnetic field component, H, which are perpendicular to
each other and both components are perpendicular to the direction of propaga-
tion. The orientation of the E vector is used to define the polarization of the wave;
if the E field is orientated vertically the wave is said to be vertically polarized.
Sometimes the E field rotates with time and it is said to be circularly polarized.
Polarization of the wave radiating from an antenna is an important concept when
one is concerned with the coupling between two antennas or the propagation of aradio wave.
A closely related parameter is the impedance of a wave; this is the ratio of E/H
= and for free space is close to 377 ohms. This is not to be confused with the
radiation resistance of an antenna; its just that they have the same units. If a
propagating radio wave encounters a medium of a different impedance, part of
the wave is reflected, much like the reflections at a discontinuity in a transmission
line. The remaining energy of the wave that passes through the discontinuity is
refracted in a different direction of propagation, just like the distortion one sees as
a light beam passes through water. The reflection and refraction properties often
depend upon the polarization of the EM wave.
The polarization of an antenna is the polarization of the wave radiated by the an-
tenna. At a given position, the polarization describes the orientation of the electric
field. The energy radiated by any antenna is contained in a transverse electromag-
netic wave that is comprised of an electric and a magnetic field. These fields are
always orthogonal to one another and orthogonal to the direction of propagation.
The electric field of the electromagnetic wave is used to describe its polarization
and hence, the polarization of the antenna. In general, all electromagnetic waves
are elliptically polarized. In this general case, the total electric field of the wave is
comprised of two linear components, which are orthogonal to one another. Each
of these components has a different magnitude and phase. At any fixed point along
the direction of propagation, the total electric field would trace out an ellipse as afunction of time. [5]
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3
DESIGN
CONSIDERATIONS FOR THE
VECTOR ANTENNA
3.1 Vector Antenna
The design of a vector antenna to be used for detection of cosmic neutrino in the
Antarctic came as a result of undetected genetic particles originating beyond the
Earth that impinge on the Earths atmosphere and the interstellar medium.
The antenna is able to recieve cosmic ray signals from all directions. Antennasare capable of detecting signals depending on the orientation of the antenna. If
an antenna is oriented along the x -axis, only the x -component of the electric
field can drive through the antenna. Hence, to be able to detect signals from all
directions we have chosen to have three dipole antennas oriented along the x, y, z
-axes. This antenna is to be deposited in ice at about 1500 meters depth.
3.2 Determining the Wavelength () for the Vector Antenna
The wavelength of a dipole antenna can be determined in relative to the antennalength and the method is as follows. = /2 for dipole, = /4 for quarter pole
antenna, and = for monopole antenna.
Therefore, in this case we use = /2 for the antenna length = 250 cm = 0.25 m.
Hence, = 2 = 0.5 m. Also considering the Electrical length of the vectorantenna which is different from the physical length, then the wavelength is ap-
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CHAPTER 3. DESIGN CONSIDERATIONS FOR THE VECTOR ANTENNA
proximately [5] = 0.95/2 with = 0.25 m, obtaining the free-space wavelength
= 20.95
= 0.526 m.
3.3 Efficiency Analysis.
From the schematic diagram, the antenna is capable of reception in x, y, z -axes
and part of an incident wave would be reflected back at the junction because of
impedance mismatch. The use of broadband matching transformer to distributethe input signal, This is an advantage to the antenna though the antenna become
more complex.
The far-field directivity can be obtain in respect to the dipole antenna on each axis
respectively since each dipole antenna is fed with different voltages. The gain
also varies from one axis to another.
3.4 Radiation Efficiency of Antenna
The radiation efficiency ecd of an antenna is the ratio of the total power radiated
by the antenna and the total supplied power. The supplied power consists of the
radiated power and power dissipated by ohmic losses in the antenna
ecd =Prad
Pin=
Prad
Prad+Pohmic(3.1)
By viewing the antenna in transmitting mode, it can be represented by a Thevenin
equivalent according to the Fig. 3.1
The antenna is represented by an impedance ZA and is given by:
ZA =RL+Rr + jXA (3.2)
where Rr is the radiation resistance and XA the antenna reactance. RL represents
both the conduction and dielectric losses of the antenna. The source of the an-
tenna is represented by an ideal generator Vg having its own internal complex
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3.4. RADIATION EFFICIENCY OF ANTENNA
Rg
Xa
RL
Rr
Xg
Vg
Ig
Source
Antenna
Figure 3.1: Thevenin equivalent transmitting mode of antenna
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CHAPTER 3. DESIGN CONSIDERATIONS FOR THE VECTOR ANTENNA
impedance Rg + Xg. The radiated power can be expressed as:
Pr =
Vg22
Rr
4(Rr+RL)2
=
Vg28
Rr
(Rr +RL)2
(3.3)
and the power dissipated in the antenna as:
POhmic = PL =
Vg2
8 RL
(Rr +RL)2
(3.4)
Now, the radiation efficiency becomes:
ecd=Rr
Rr+RL(3.5)
Hence, RL should be very low compared toRr and it should not be chosen too large
because, the antenna impedance should be conjugately matched to the generator
impedance.
3.5 Antenna Loss ResistanceThe antenna loss resistance consists of the conductor and dielectric losses, which
for many antenna it is difficult to calculate. But for a wire antenna it can be cal-
culated accurately from the conductor length and cross-sectional area A which
carries a uniform current density. The DC resistance is;
RDC =
A(3.6)
Where is the conductivity of the conductor material. At high frequencies the
current tends to concentrate to the outer surface of the conductor. This phenom-ena is called the skin effect.
The high frequency resistance can be define in terms of the skin depth
skin dept [7]
=1
f(3.7)
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3.5. ANTENNA LOSS RESISTANCE
Where is the permeability of the material and f is the frequency in Hz for in-
stance the skin dept for copper.
= 5.8107/m, =o = 4107H/m
skin depth can be written as;
= 0.0661f frequency in Hertz
As the frequency increases, the current begins to move from an equal distribution
through the conductor cross-section towards the surface depending on the con-
ductor bulk resistivity. At surficiently high frequencies all the current are flowing
within a very thin layer close to the surface.
However, the current concentrates nearest to the surface that is about the highest
relative dielectric constant. Lower bulk resistivity result in shallower skin depths.
For a solid wire the current concentrates on the outer surface for this reason, when
skin depth is shallow the solid conductor can be replaced with a hollow tube with
no perceivable losses of performance. The choice of a plating material can de-
grade performance (increase attenuation) if its bulk resistivity is greater than thatof the copper.
Hence skin depth can be calculated as follows; [7]
s =
2
..=
P
2(3.8)
RHF =l
2bRs (3.9)
Rs = surface resistance. In analogue with equation (3.6), we obtain
Rs =1
=
.f.(3.10)
The high-frequency resistance becomes;
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CHAPTER 3. DESIGN CONSIDERATIONS FOR THE VECTOR ANTENNA
RHF =l
2b
2(3.11)
The loss resistance is RL = RHF but for a half-wavelength dipole RL =12RHF
3.6 Determining the Operation Frequency for the Vector An-
tenna
The actual operating frequency is determined by considering the refractive index
of the environment or the region where the antenna is to be used, for this design
we are considering ice. Hence, the refractive index of ice at microwave frequency
is = 1.78 [3]. Following the calculation below,
= kc (3.12)
while c =
=kc
= 1 for free space (3.13)
=kc
= 1.78 for Ice (3.14)
where c = 3108m/s
k = 2
= 2
from the expression of a dipole above = 0.25 m.
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3.7. DESIGN CONSIDERATIONS
and = 2
then = 0.526 m.
=c
(3.15)
= 3108
0.5261.78 = 320 MHz.
3.7 Design Considerations
The UHEC antenna is designed to be installed in the ice at a depth of 1500 m
in a hot water drill-hole in the Antarctic, The antenna comprises of three dipole
antenna aligned in the x, y, z -axes with frequencies of 320 MHz. The dipole
antennas are enclosed in a spherical plastic capable of withstanding a pressure of
about 1000 Bar.
Simulations have been done to ensure that the antenna enclosure are properly
chosen and selected to withstand future deterioration or environmental effect on
the antenna enclosure, and various effects were observed to improve the simula-
tion results. Also simulations are run for the dipole antenna itself to ensure better
performance, Part of an incident wave would be reflected back at the junction
because of impedance mismatch. The use of broadband matching transformers
to distribute the input signal is an advantage to the antenna though the antenna
become more complex.
The far-field gain can be obtain in respect to the dipole antenna on each axes re-
spectively since each dipole antenna is fed with differently. The gain also varies
from one axis to another.
3.8 Ultra HighEnergy Cosmic Neutrino (UHEC) Antanna
The frequency of operation of the UHEC antenna is at 320 MHz according to
design specification.
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CHAPTER 3. DESIGN CONSIDERATIONS FOR THE VECTOR ANTENNA
Broadband antennas have been studied for short pulse applications typically trad-
ing phase linearity with gain. The UHEC antenna can easily reach a low standing
wave ratio over several octaves due to its asymmetrical structure.
However the electrical size of ground axis increases at high frequencies and the
radiation pattern is reflected away from azimuthal axis.
The radiation is made broadsided so that all frequency components are transmitted
and received simultaneously.
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4
MECHANICAL
CONSTRUCTION
4.1 Mechanical Considerations for Design
Certain measures have been considered for the mechanical construction and de-
sign of the UHEC antenna to make sure that it is strong enough to withstand
stress and pressure during and after the installation of the antenna. Such measures
include selecting a proper cable for communication between the antenna and the
surface, three double-shielded coaxal cables supported by integrated steel wires
and is capable of operating in the ice under high pressure without squeezing or
rupturing. The cable is connected to the antenna via an underwater pressure tight
connector strong enough to withstand a pressure at about 1000 Bar in ice. The
central part made of plastic has been constructed sufficiently strong to make sure
that it cannot be broken. In order words, proper considerations and measures have
been taken to make sure that the cable is suitable for the demanding environment.
4.2 The Cover of the Antenna
The material used for the antenna cover is plastic peek, the chemical propertiesfor peek is polyetheretherketones or polyketones obtained from aromatic dihaldes
and bisphenolate salt by uncleophilic substitution. Peek is a thermoplastic with
extraordinary mechanical properties, its tensile strength is 170 MPa and melt at
temperature 3500C. The raw material is manufactured in Kiruna in the north of
Sweden.
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CHAPTER 4. MECHANICAL CONSTRUCTION
4.3 The material for the Antennas
Different materials, such as brass, aluminium, titanium, copper, and stainless
steel, have been considered for the antennas. Among these materials, stainless
steel was chosen because it does not corrode easily and it is heavy to be sus-
pendend in a hot water-drilled hole.
4.4 Mechanical Model And Drawings of the Vector AntennaThe drawing tools used for this project design is the 3D cad program Solid works
office premium 2006 developed in the United States of America. The program
allowed pressure simulations to be made on the model, as well as making 2D
drawings.
Figure 4.1: Top model made of peek
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4.5. GEOMETRY ALIGNMENT FOR A 3D OBJECT
4.5 Geometry alignment for a 3D object
Proper Calculation of the mid point of the model has been made for the 3D an-
tenna to ensure that the antenna is properly positioned, figure 4.3 show more detail
about the angle formed by the antennas to the centre. considering the geometry:
ca1
= cos
ba/2
= tan 6
= 13
c2 = a2
4+ b2 = a
2
4+ 1
3a2
4= a
2
3 c =
a3
c/a = 13
= cos
= arccos 13
= 54.730.
Hence the angle between the center of the model to the antennas is measured to
be 54.730, for a proper geometrical positioning of the antennas in 3D.
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CHAPTER 4. MECHANICAL CONSTRUCTION
54.74
15.
50
A
A
24
44
26.
50
48.36
39.76
4.20
DO NO T SCALE DRAWING
FINISH
MATERIAL Peek
REV.
APPLICATION
USED O NNEXTASSY
0.001
. ANYREPRODUCTION IN PARTOR AS A WHOLE
THP
PROPRIETARY AND CON FIDENTIAL
THEINFORMATION CONTAINED IN THIS
ISPROHIBITED.
DWG. NO.SIZE
0.01
CO MMENTS:
SHEET1O F1
Q.A.
MFG APPR.
WITHOUTTHE WRITTEN PERMISSION O F
ENG APPR.
WEIGHT:
NAME
0.01
CHECKED
DRAWN Ayobam i IJI
A
DATE
DRAWING ISTHESOLE PROPERTY OF
DIMENSIONSA REIN MM
TOLERANC ES:0.01FRACTIONAL 0.01ANGULAR: MACH 0.01degBEND 0.01TWO PLACEDECIMAL 0.01THREEPLACE DECIMAL
SCALE:1:1
SECTION A -A
21.
60
27.
60
6.
20
4.57
31.
60
3.12
Figure 4.2: Machine drawing of the top model
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4.5. GEOMETRY ALIGNMENT FOR A 3D OBJECT
T
h
c
a1
a2
a/2
a3
b
O
S
Considering the triangle OST we can calculate thevalue of angle
From the figure a1 = a2 = a3and line ST = a/2 this is mid point along line a1
The line h is the height and the point O is the centre of thefigure
Figure 4.3: Angle formed by the orthogonal antennas with centre
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CHAPTER 4. MECHANICAL CONSTRUCTION
Figure 4.4: Bottom model
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4.5. GEOMETRY ALIGNMENT FOR A 3D OBJECT
SIZE
WEIGHT:
newMODL12
PROPRIETARY AND CO NFIDENTIAL
DWG. NO.
AREV.
MATERIAL
FINISH
DO NO T SCALE DRAWINGPROHIBITED.
CO MMENTS:
SHEET1O F1
Q.A.
ISWITHOUTTHE WRITTEN PERMISSION O F
REPRODUCTION IN PARTOR AS A WHOLE
0.01
ENG APPR.
CHECKED
DRAWN Ayob ami IJI
DATENAME
-
+
USED O N
MFG APPR.
. ANY
0.001
DRAWING ISTHESOLE PROPERTY OF
THEINFORMATION CONTAINED IN THIS
NEXTASSY
APPLICATION
DIMENSIONSA REIN MMTOLERANC ES: 0.01FRACTIONAL 0.1ANGULAR: MACH 0.01deg.BEND 0.01
TWO PLACEDECIMAL 0.01THREEPLACE DECIMAL
SCALE:1:1
38
4.6
2
4.57
30
343
1.6
0
3
54.74
1.2
02
13
44
39.76
49
M24
2 x-DEPTH> 3
A
A
Figure 4.5: Bottom model machine drawing
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CHAPTER 4. MECHANICAL CONSTRUCTION
The Vee band are used to fasten the top and bottom models together by
providing adequate support for the models from falling apart or leakage
of its content, through its grooves that key into the top and bottom mod-
els. The pair of Vee band is then fasten together with screw at both ends.
Figure 4.6: Vee band
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4.5. GEOMETRY ALIGNMENT FOR A 3D OBJECT
M
5.5
0
9.2
06.8
0
2.7
0
2.5
0
M2.50
ADWG. NO.SIZE
WEIGHT:
REV.
MATERIAL
FINISH
DO NO T SCALE DRAWINGAPPLICATION
USED O N
-
+
PROHIBITED.
CO MMENTS:
PROPRIETARY AND CO NFIDENTIAL+
NAME
DRAWING ISTHESOLE PROPERTY OF
-
THEINFORMATION CONTAINED IN THIS
SHEET1O F1
Q.A.
MFG APPR.
0.01
CHECKED
DRAWN Ayobami IJI
ISWITHOUTTHE WRITTEN PERMISSION O F
0.001
REPRODUCTION IN PARTOR AS A WHOLE
0.01
ENG APPR.
DATE
VVBB
. ANY
NEXTASSY
DIMENSIONSA REIN MMTOLERANC ES:0.01FRACTIONAL 0.01ANGULAR: MACH 0.01degBEND 0.01
TWO PLACEDECIMAL 0.01THREEPLACE DECIMAL
SCALE:1:1
SECTION A-A
3.5
0
39.758.63
47.51
R22
A
A
Figure 4.7: Vee band machine drawing
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CHAPTER 4. MECHANICAL CONSTRUCTION
Figure 4.8: Antenna with fittings
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4.5. GEOMETRY ALIGNMENT FOR A 3D OBJECT
NEXTASSY USED O N
APPLICATION DO NO T SCALE DRAWING
0.001
. ANYREPRODUCTION IN PARTOR AS A WHOLE
DRAWING IS THESOLE PROPERTY OF
NAME DATE
ADWG. NO.SIZE
WEIGHT:
fitting + a ntenna
PROPRIETARY AND CON FIDENTIAL
THEINFORMATION CONTAINED IN THIS
ISWITHOUTTHEW RITTEN PERMISSION O F
PROHIBITED.
MATERIAL: Stainlesssteel and Co pp er.
REV.
CHECKED
SHEET1 OF1
Q.A.
MFG APPR.
CO MMENTS:
FINISH
ENG APPR.
DRAWN Ayobam i IJI
DIMENSIONSA REIN INCHESTOLERANC ES:0.01FRACTIONAL 0.01ANGULAR: MACH 0.01BEND 0.01
TWO PLACEDECIMAL 0.01THREEPLACE DECIMAL
SCALE:1:2
SECTION A -A
7
4.
20
1585 25
5
A
A
125
Figure 4.9: Antenna with fitting
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CHAPTER 4. MECHANICAL CONSTRUCTION
The printed circuit board has a diameter of 31.6 mm and a thickness of 1.4 mm
also on it are holes to allow free flow of transformer oil called Flourine in
swedish inside the model. The flourine oil will provide cooling for the electron-
ics and prevent the lectronics from damage or deterioration in ice over years.
Figure 4.10: Electronics circuit board.
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4.5. GEOMETRY ALIGNMENT FOR A 3D OBJECT
Figure 4.11: complete model
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CHAPTER 4. MECHANICAL CONSTRUCTION
Vee band
Top m odel (pe ek)
Bottom model (peek)
Plug
Printed c ircuit b oard
with a mplifiers
O ring
Oil drain hole
Antenna rod)
Vee band
Top m odel (pe ek)
Bottom model (peek)
Plug
Printed c ircuit b oard
with a mplifiers
O ring
Oil drain hole
Antenna rod)
Figure 4.12: Internal structure of complete model
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4.5. GEOMETRY ALIGNMENT FOR A 3D OBJECT
Figure 4.13: Finished tripole antenna. Photo by T. Thrnlund
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5
VECTOR
ANTENNA PERFORMANCE
5.1 Electrical Properties of the Antenna Medium or Environ-
ment
The medium or environment of the 3D antenna is Ice at about 450C to 700Cat a depth of 1500 meters and pressure of 1000 Bar. Ice is transparent to visible
light. It has the lowest index of sodium D line of any known crystalline material.
It is double refracting, uniaxial, optically positive with very small birefringence.The proton disordered phases have a broad infrared absorbtion band for the fun-
damental intramolecular bending and stretching vibrations.
5.1.1 Electromagnetic Wave in Ice
At frequencies from 5 to 300 MHz the loss of energy by absorption in Ice is suffi-
ciently small that they can penetrate large Ice masses great distances. Radio waves
are reflected by inhomogeneities in the ice and at material boundaries, especially
at the ice - water and ice - rock interfaces.
5.2 UHEC Antenna Amplification
We use (LTC6400-20) a product of Linear technology corporation, 1.8 GHz Low
Noise, Low distortion differential ADC driver for 300 MHz IF, for the amplifica-
tion of the UHEC antenna.
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CHAPTER 5. VECTOR ANTENNA PERFORMANCE
The LTC6400-20 is a high-speed differential amplifier targeted at processing sig-
nals from DC to 300 MHz. The part has been specifically designed to drive 12,
14 and 16-bitADCs with low noise and low distortion, but can also be used as a
general-purpose broadband gain block. It is easy to use, with minimal support
circuitry required. The output common mode voltage is set using an external
pin, independent of the inputs, which eliminates the need for transformers or AC-
coupling capacitors. The gain is internally fixed at 20dB(10V/V). The LTC6400-
20 saves space and power compared to alternative solutions using IF gain blocks
and Transformers. The Amplifier is packaged in a compact 16-lead 3 mm
3mm
QFN package and operates over the 400C to 850C temperature range, Storagetemperature range is 650C to 1500C, Maximum Junction Temperature is 1500Cand Lead Temperature (soldering, 10 second) is 3000C. [6] The supply voltage
peak to peak is 3.6volt and input current 10mA. Figure 5.1 is the electronicscircuitry of the vector antenna.
5.3 Vector Measurements
5.3.1 The 3D E-field antennas
The vector antenna has full Polarization Coverage and the antenna Intensity |E|2is a scalar with three times higher detection probability.
5.4 Vector Pulse Post-Processing
The amplifier coupled to the antennas improves the signal to noise ratio com-
pletely and the pulse shape will also improve making the antenna to perform bet-
ter without causing noise to other equipment in its environ.
Using the Hilbert transform to obtain analytic complex signal [4]
H [s(t)] = s(t) =1
s(t
)
t t dt
(5.1)
Evaluating the integral as the Cauchy principal value, it can be written
s(t) =1
t s(t). (5.2)
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CHAPTER 5. VECTOR ANTENNA PERFORMANCE
The Hilbert transform can be considered as a filter that shift phases of all fre-
quency components of its input signal. Let us consider an analytic (complex)
time signal, E(t). It can be constructed from a real valued input signal Re{E(t)}as shown in Eq. (5.3),
E(t) Re {E(t)}+ iIm {E(t)} , (5.3)
where, E(t) is the analytic signal constructed from Re {E(t)} and its Hilbert trans-form, iIm {E(t)}.
Calculating the eigenvalues and eigenvectors, using for instance a SingularValue Decomposition (SVD),
Exx+Eyy+Ezz E1e1+E2e2+E3e3. (5.4)
The eigenvector en corresponding to the largest eigenvalue En contain the sig-
nal, and the eigenvector corresponding to the smallest eigenvalue contains the
noise signal. The post-processed signals for the input and output signal are shown
below:
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5.4. VECTOR PULSE POST-PROCESSING
The antenna input signal
The processed signal from the antenna
Figure 5.2: Simulation of vector pulse processing. The pulse record is
64 samples long. At 1 Gsamp/s corresponding to 64 ns.
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6
ELECTRICAL
SIMULATION OF
ANTENNA
The method of simulation used in this project is the Numerical Electromagnetic
code (NEC) is a method of moments (MOM) for wire antennas developed by
Lawrence Livermore National Laboratory in the early 1980s. Since then it has
been widely used in antenna simulations and design. In this project the second
version (4NEC2X) is used for simulating the radiation pattern of the vector an-
tenna.As earlier discursed the Electric dipole antenna is one of the oldest, simplest, and
most common type of antennas. In this case it is observed as a straight linear
wire of high Electrical conductivity. The Electric dipoles can be divided into dif-
ferent categories depending on their length and the wavelength of the dipole, for
infinitesimal dipole antennas the length is less than /50 for small electric dipole
antennas the length is greater than /50 and less than /10 and for finite electric
dipoles where the length is greater than /10 also for half wave electric dipole the
length is equal to /2. Hence the antenna frequency is determined to be 320 MHZ
that is been used for the electrical simulations, figures below shows the electric
dipole antenna simulations for an ideal situation.
During the simulations it is assumed that the vector antennas are in phase and theyhave thesame amplitude.
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CHAPTER 6. ELECTRICAL SIMULATION OF ANTENNA
Figure 6.1: Orthogonal Vector antennas total gain
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Figure 6.2: Orthogonal vector antennas total gain
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CHAPTER 6. ELECTRICAL SIMULATION OF ANTENNA
Figure 6.3: vector antennas total gain
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Figure 6.4: Vertical gain
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CHAPTER 6. ELECTRICAL SIMULATION OF ANTENNA
Figure 6.5: vertical gain orthogonal dipole
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Figure 6.6: Horizontal gain
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CHAPTER 6. ELECTRICAL SIMULATION OF ANTENNA
Figure 6.7: horizontal gain orthogonal dipole
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Figure 6.8: horizontal axis total gain 3D orthogonal dipole
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CHAPTER 6. ELECTRICAL SIMULATION OF ANTENNA
Figure 6.9: vertical axis total gain 3D orthogonal dipole
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7
CONCLUSION
The vector antenna is a quite an interesting project for research work. Very low
mutual coupling between the axially placed dipoles was maintained. The concept
of the vector antenna is to receive signal in x, y, z -axes in the antarctic Ice where
the antenna cannot rotated but remain in a fixed position, the structure is stronge
enough to withstand high pressure in ice and in underwater applications.
Vector antenna for ultrahigh energy cosmic neutrino detection with three orthog-
onal dipoles, in the frequency of 320 MHz, all at an angle of 90 degree to one
another. I was able to observe, the total gain in all direction, we have used pre-amplifiers to boost the signal and to improve SNR of the vector antenna.
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ACKNOWLEDGEMENT
My profound gratitude goes to my supervisor, Dr Jan Bergman, at the Swedish
Institute of Space Physics, who has immensely contributed to this Master thesis
with motivations and advice.
Special thanks goes to people who has contributed mentally, materially, and oth-
erwise to the success of this project; such include Dr Roger Karlsson, my subject-
examiner, Mr Walter Puccio and Mr Kiran Kumar Kovi who designed the elec-
tronics circuit board, Mr Bertil Segerstrom, Dr Thomas Leyser, Mr Lennart Ahlen,
Prof. Bo Thide, and all other staff of Swedish Institute of Space Physics.
I give thanks to the following groups for their advice and collaborations: Prof.
Lars Stenmark at Uppsala University, who came up with the original idea to the
antenna design, Mr Sone Sdergren, Maintenance superintendent of the mechani-
cal workshop at the
Angstrom laboratory, Dr Hugo Nguyen and Dr Henrik Kratz atAngstrom Space Technology Centre, Dr Leif Gustafsson and Dr Allan Hallgren
at the Department of Nuclear and Particle Physics, Dr Fredrik Bruhn and Miss
Jenny Davidsson at the Angstrom Aerospace Corporation, who provided software
and support for drawing the model, the Department of underwater research at the
Swedish Defence Research Agency (FOI) for their advice and hospitality during
my visit there, and to Ericsson Cable in Hudiksvall for their advice.
I would like to thank the PI of IceCube, Prof. Francis Halzen at the University of
Wisconsin, as the originator of this project, as well as the PI of RICE, Prof. David
Besson at the University of Kansas for his kind support.
I also use this opportunity to say thank you to my colleagues in the project room:
Mr Martin Wger, Miss Monica Alaniz, and Mr Peter Lekeaka Takunju, for their
cooperations.
Thank you all.
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BIBLIOGRAPHY
[1] ARENA 2006: Acoustic and Radio EeV Neutrino detection Activities, Jour-
nal of Physics: CONFERENCE SERIES 81 (2007) 012024.
[2] ICECUBE RESEARCH AND DEVELOPMENT:
http://www.ps.uci.edu/superk/neutrino.html,
http://www.icecube.wisc.edu/info/antarctic/,
http://hyperphysics.phy-astr.gsu.edu/hbase/particles/neutrino.html
[3] MATTHEW N.O. SADIKU: Refractive index of snow at microwave frequen-
cies, Applied Optics.,vol. 24, No.4, 15 february, 1985.
[4] LEO N COHEN: Time - Frequency Analysis, Prentice Hall Signal Processing
Series, Alvan V. Oppenheim, Series Editor.
[5] BALANIS, C.A.: Antenna Theory, analysis and design, 2nd Ed., John Wiley
and Sons, 1997.
[6] LINEAR TECHNOLOGY: Linear Technology Operational Amplifier Product
Manual
[7] POZAR, DAVID M.: Microwave Engineering, 3rd Ed., John Wiley and Sons,
2004.
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