DESIGNING AND CONSTRUCTING A VLF RADIO TELESCOPEWITH AN EXTERNAL FILTER TO RECEIVE SUDDEN IONOSPHERIC DISTURBANCES (SID) IN IRANIAN LOCATION

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International Journal on
“Technical and Physical Problems of Engineering”
(IJTPE)
Published by International Organization of IOTPE
ISSN 2077-3528
IJTPE Journal
www.iotpe.com
ijtpe@iotpe.com
June 2015
Issue 23 Volume 7 Number 2
Pages 34-38
34
DESIGNING AND CONSTRUCTING A VLF RADIO TELESCOPE WITH AN
EXTERNAL FILTER TO RECEIVE THE SUDDEN IONOSPHERIC
DISTURBANCES (SID) IN IRAN
M. Marbouti 1 M. Khakian Ghomi 1 M.R. Salmanpour 1 K. Ghanbari 1 B. Nahavandi 2
L.M. Tan 3
1. Energy Engineering and Physics Department, Amirkabir University of Technology, Tehran, Iran
marjanmarbouti@yahoo.com, mehdi.khakian@yahoo.com, m.salmanpoor66@yahoo.com, keyvanghanbari@gmail.com
2. Kermanshah Branch, Islamic Azad University, Bakhtaran, Iran, behzadnahavandi@yahoo.com
3. Faculty of Natural Science and Technology, Tay Nguyen University, Buon Ma Thuot, Dak Lak, Vietnam
tantaynguyen82@yahoo.com
Abstract- In this paper after the design and construction
of the radio telescope system in the VLF region, we study
the effects of atmospheric disturbances, especially solar
bursts (Solar flares) on earth’s Ionosphere. Our radio
telescope receives the 26.7 KHz signal of source station
TBB (Bafa, Turkey). Then the radio signals of solar flares
received by our radio telescope are investigated by
software SSRT Robot2 and spectrum lab.
Keywords: VLF Signals, Solar Flare, Sudden
Ionospheric Disturbances
I. INTRODUCTION
Ionosphere is the part of Earth's atmosphere at
altitudes above about 60 km which is formed due to the
x-ray and ultraviolet radiation of the sun. Due to the
interaction between the radiation and earth’s atmosphere,
electrons are separated from molecules or atoms in that
height and can move freely in the Earth's magnetic field.
Therefore ionosphere can be summarized as a conductive
layer.
On the other hand, ionosphere is divided into different
layers because of various intensity and penetrating power
of solar radiation: layers D, E, F1 and F2. The D layer
only exists during day and F1 and F2 layer change to one
F layer at night. The sun affects directly on the ionization
of layers of the ionosphere. There are many VLF stations
around the world, which these VLF stations send VLF
waves to communicate with submarines.
These waves collide with layers on their way within
Ionosphere and reflect due to the electron density
gradient of these layers. Solar swings and bursts and also
signal changes at sunrise and sunset can be observed via
received signals from these stations.
II. SIGNAL ANALYSIS OF SIMILAR RADIO
TELESCOPES
Regarding the changes in electron density in different
layers in ionosphere at night and day and the sent waves
from VLF stations toward this layer, the reflected waves
from that layer and received signal on the ground change,
consequently the solar fluctuations can be realized via
observing the changes in received signal. During the
night, the sun's radiation is less.
As a result, the ionization is less and D layer
disappears and VLF signals reflect from E and F layers.
This phenomenon increases the VLF signal strength at
night. When sun rises, the D layer is ionized a little and
this causes the D layer to absorb the VLF signals. After 1
or 2 hours its reflecting ability is again high. VLF signals
sent daytime are reflected, although the reflection is not
as strong as night. We all have experienced to receive
higher quality the radio signals at night.
During a solar explosion (Solar Flare), hard x-ray is
radiated and this radiation increases ionization of layer D,
100 times more than a day without solar flare. This event
increases the electron density in the D layer and this
cause to have a peak due to solar flares in the signals
chart received from VLF stations: (Figures 1)
Figure 1. The VLF signal pattern during a day and night with solar
flares
These phenomena are called SID (Sudden Ionospheric
Disturbances). This paper aims to study the observed
solar flares and the signal reductions during sunrise and
sunsets [2, 3].

International Journal on “Technical and Physical Problems of Engineering” (IJTPE), Iss. 23, Vol. 7, No. 2, Jun. 2015
35
In order to receive VLF Radio waves we needed an
antenna which is able to receive signal from each
considered station. Loop antennas were used to receive
these signals.
A. Methods and Formalism
1. The selection of desired transmitter to receive VLF
frequency in Iranian location:
A good transmitter should have the following attributes to
become an appropriate option to perform monitoring
operations.
A. Possessing the highest transmission ability
We should try to select a transmitter with highest
transmitting ability to be able to easily be distinguished
from ground noise (unfortunately, due to the military
reasons, the ability and power of many VLF stations is
not given)
B. The ideal distance between 500 km to 5000 km related
to the power of transmitter
If you sit at an unnecessary close distance to the
transmitter, it is possible that you receive even the least
disruptions of the ionosphere, if you are at an
unnecessary farther distance from transmitter, it is
possible that the received signals are weakest; these two
phenomena are not appropriate. So the legal or acceptable
distance should be maintained for this task. [5] After
carrying out all necessary evaluations and studies, we
reached the conclusion and understanding by using the
Movable Type Scripts’ software, that the TBB transmitter
located in Bafa, Turkey is an appropriate transmitter for
our objective, which possesses a working frequency of
26.7 kHz.
2. The measurements and calculations, and related
formulas to build loop shape antenna (Octagonal):
The frequency (f) of antenna resonance depends on
inductance (L) of wire loop, and the capacitance capacity
of total (C).
1
2
fLC


(1)
The inductance of a loop depends on using wire’s
thickness in antenna structure, its diameter and the
number of wire rounds.
28
ln 1.75
r
L rN R





(2)
In view of this fact, that the VLF transmitter which will
be used to receive frequency, uses a transmitting
frequency of 26.7 kHz, therefore, we put f = 26700 Hz in
Equation (1).
11
11
26700 26700 2
2
3.55e
LC
LC
LC



   

(3)
Now we refer to Equation (2), and on the basis of the
existing experience and the availability of the parts in
market, arrange a, 0.55 mm diameter wire. We consider
the radius of the antenna about, r = 0.4 m and N = 100
rounds, substitute these values in Equation (2),
D = 0.55 mm, R = 0.275 mm so, we have: L = 38.2 mH.
This ‘L’ value is reasonable to continue the
assignment. Now substitute L = 38.24 mH in the result of
Equation (1), so we shall have the following:
-11 -3 -11
11 3
=(3.55*10 ) 38.24*10 C=3.55*10
3.55*10 / 38.24*10
LC
C


919 pfC
(Total capacitance capacity)
Considering the above calculations, the designed antenna
will have the specifications in Table 1.
Table 1. Specifications of designed antenna
Antenna
diameter (d)
Wire diameter
(D)
L
C
80 cm
0.55 mm
38.24 MH
919 Pf
The C is called total capacity of the capacitance:
C = C' + C' (4)
Each antenna has a C', which is specific to the antenna
itself. To find the C', we arrange a Coil of equal diameter
to antenna, which has fewer rounds of winding. Antenna
and the coil are placed against each other at a distance of
few meters, now we connect the two, ‘first and last wire
ends’ of the coil to generator signal. From the other side,
the two first and last wire ends of the antenna are
connected to the oscilloscope, and the signals of the
oscilloscope and generator are switched on, and
frequencies are given to 1 kHz gorge or span for antenna,
while the receiving voltage value is noted and registered
by the help of oscilloscope described in Table 2.
Table 2. Transmitted frequency and receiving voltage in gorge of 1 kHz
It was observed that in 31 kHz frequency, a very high
voltage is produced, hence, we noted that the antenna
resonance frequency locates around 31 kHz. Repeat the
above steps to have higher degree of precision for lesser
gorges of 1 kHz shown in Table 3.
Receiving
voltage by
antenna and
oscilloscope
(V)
Induced
frequency to
coil through
generator
signal (kHz)
Receiving voltage
by antenna and
oscilloscope (V)
Induced
frequency to
coil through
generator
signal (kHz)
0.85
23
0.2
3
0.95
24
0.25
4
1.10
25
0.3
5
1.2
26
0.35
6
1.5
27
0.38
7
2
28
0.4
8
2.8
29
0.41
9
4.6
30
0.41
10
18
31
0.42
11
5.8
32
0.42
12
3
33
0.44
13
1.8
34
0.48
14
1.4
35
0.5
15
1.1
36
0.55
16
0.9
37
0.58
17
0.7
38
0.6
18
0.6
39
0.62
19
0.5
40
0.65
20
0.7
21
0.8
22

International Journal on “Technical and Physical Problems of Engineering” (IJTPE), Iss. 23, Vol. 7, No. 2, Jun. 2015
36
Table 3. Transmitted frequency and receiving voltage in gorge of 0.1 kHz
Receiving
voltage by
antenna and
oscilloscope
(V)
Induced
frequency to
coil through
generator
signal (kHz)
Receiving
voltage by
antenna and
oscilloscope
(V)
Induced
frequency to
coil through
generator
signal (kHz)
12
31.5
18
31
10
31.6
19
31.1
9
31.7
20
31.2
8
31.8
19
31.3
6
31.9
16
31.4
In view of the above data, the resonance frequency of
antenna is 31.2 kHz. Now by noticing Equation (1), we
calculate C', we have: C = C' + C'', 919 pf = 679.9 pf +
C''  C'' = 239.1 pf.
Thus, in order to bring 31.2 kHz to 26.7 kHz value,
the variables of about 239.1 Pf should be mounted on
antenna to bring the frequency to 26.7 kHz.
3. Designing and building of an ‘Amplifier Circuit’:
The designed looped antenna receives 26.7 kHz
frequency for us; for better reception of this frequency,
this frequency should be boosted and amplified. An
amplifier is necessary to reach this aim, In the previous
step, the filtering process of receiving signal was
conducted on 26.7 kHz; so, there is only a need of
amplifying these signals (i.e. amplifier accompanied with
outer filter). In fact, our circuit is comprised of two
phases or stages of pomp so that each of the stages
performs amplification to 20 gains (2020=400). For our
target It is enough to use first stage or phase of (20 gains)
as shown in Figures 2 and 3.
Figure 2. Amplifying schematic circuit with outer filter
Figure 3. Constructed circuit
4. Connectivity of the amplifying circuit to antenna
and its testing (by generator signal in laboratory):
In this stage, 2x0.7 kHz frequency was transmitted to
designed antenna by generator’s signal and the coil,
expecting to observe the ‘noise less’ signal on the
oscilloscope as shown in Figure 4.
Figure 4. Signal observation without noise by generator signal in
laboratory
5. Connectivity of the amplifying circuit to antenna
and its testing (without connectivity to generator’s signal
and in open atmosphere):
This step was performed like stage 2.4 with a difference
that we shifted and transferred the set of antenna and
amplifier circuit to open atmosphere where we directly
received the signal from sky as shown in Figure 5.
Figure 5. Signal receiving on oscilloscope in open atmosphere
6. The connectivity of SSRT to sound card, installing
of Spectrum Lab and SSRT Robot2 software, as well as
output receiving through them
After connecting the system to the computer's sound
card, Spectrum lab software installed on the computer
gets the data in one-minute intervals as boarding began.
We observed that the frequency of our system 26.7 KHz.
Other high frequency VLF stations around the country
will receive after we decided to get and charting stations
would also are shown in Table 4 and Figure 6 [6].
Table 4. VLF transmitting stations, that SSRT has the ability to receive
signals from them
Distance
from Iran
(km)
Transmitter
location
VLF
transmitter
Frequency
4046.8096
Vijayanarayanam,
South India
VTX
16.3 kHz
2158.2455
Bafa, Turkey
TBB
26.7 kHz
3297.0614
Nescimi, Italy
NSY
45.9 kHZ

International Journal on “Technical and Physical Problems of Engineering” (IJTPE), Iss. 23, Vol. 7, No. 2, Jun. 2015
37
Figure 6. A picture from spectrum lab with flashes on picture which
specified the signals of 16.3, 26.7 and 45.9
III. RESULTS AND DISCUSSION
Simultaneous analysis of SSRT radio telescope’s
diagram and the diagram of X-ray solar flares for Iranian
station:
In this section, the VLF transmitter in the city of Bafa
of Turkey and the receiver SSRT in Tehran (Iran), are
situated at a distance of 2158.2455 km from each other,
while the SSRT in addition to receiving frequency of 26.7
kHz from TBB transmitter situated in Turkey (as pointed
to it in previous sections), also receive the frequencies
from VTX with a working frequency of 16.3 kHz situated
in India, as well as, NSY transmitter with a working
frequency of 45.9 kHz situated in Italy. Figure 7 of
receiving diagram and depicted by Excel located in Iran,
relates to 15/12/2011; has simultaneously received data
from VTX and TBB as well as NSY stations, the effects
of sunrise and sunset can be clearly observed.
Figure 8 as receiving diagram, with SSRT Robot2
from X-ray solar flares relates to the GOES satellite,
downloaded on 15/12/2011 which is in correspondence
with Hong Kong time and as per UT+8 world clock. By
comparing these two Figures, we will observe that an X-
ray Solar flare exists in Figure 9 at about 10 o’clock
corresponding Iranian standard time.
As we know, the world time in accordance with
Iranian time is in the form of UT+3.5; so, the time
difference between Iran and Hong Kong ((UT+8)-
(UT+3.5) =4.5h) is four hours and thirty minutes. As a
result, we can receive the X-ray solar flares occurred at
10 o’clock in Iran; at 14:30 corresponding to Hong Kong
time, four hours and thirty minutes after the occurrence of
X-ray solar flares in Iran. By observing Figure 8, we find
this phenomenon has been taken place.
Figure 7. The occurrence of X-ray solar flares, at about 10 o’clock
corresponding to Iranian standard time
(received by SSRT radio telescope in Iran)
Figure 8. The occurrence of X-ray solar flares, at about 14:30 o’clock
corresponding to Hong Kong standard time (received by Goes satellite)
IV. CONCLUSIONS
Permanent- The objective of this project was to
design and build a SSRT radio telescope and receive the
solar flares, furthermore to observe the effects of sunrise
and sunset. After the studies were made during work
process, it was noticed that the obtained result was in
good conformity with the global data received from
GOES satellites. Our next theme is to study the total
effects of ionosphere on SSRT radio telescope. Some
significant points of which are expressed as follows:
 Earthquake effect on the findings or receivables of
SSRT (7)
 HARRP effect on the findings (or receivables) of
SSRT
 Observing the occurring time of Thunder and the
study of its intensity
 Meteor downfall
 Sun and Moon eclipses
 Phenomena influenced and effected by Gamma rays
explosions
 The electrical disruptions effect rate on the findings or
receivables of SSRT
ACKNOWLEDGEMENTS
The great work of Mr. Rodney Howe who helped us a
lot to construct this antenna and also Dr. Mahboubeh
Jalalpour and Ms. Parvin Arasteh for supporting us in this
scientific works.
REFERENCES
[1] M. Wayne, N.R. McRae, Thomson, “Solar Are
Induced Ionospheric D-Region Enhancements from VLF
Phase and Amplitude Observations”, Journal of
Atmospheric and Solar-Terrestrial Physics, Vol. 66, pp.
77-87, 2004.
[2] D.H. Zhang, X.H. Mo, L. Cai, W. Zhang, M. Feng, Y.
Q. Hao, and Z. Xiao, “Impact Factor for the Ionospheric
Total Electron Content Response to Solar Flare
Irradiation”, Journal of Geophysical Research, Vol. 116,
A04311, DOI:10.1029/2010JA016089, 2011.

International Journal on “Technical and Physical Problems of Engineering” (IJTPE), Iss. 23, Vol. 7, No. 2, Jun. 2015
38
[3] V. Zigman, D. Grubor, D. Sulic, “D-Region Electron
Density Evaluated From VLF Amplitude Time Delay
During X-Ray Solar Flares”, Journal of Atmospheric and
Solar-Terrestrial Physics, Vol. 69, pp. 775-792, 2007.
[4] A. Kolarski, D. Grubor, “Study of the X-Ray Flare
Induced Lower Ionosphere Changes by Simultaneous
Monitoring of GQD and NAA VLF Signals”, Publ.
Astron. Obs. Belgrade, No. 91, pp. 353-356, 2012.
[5] A. Percival, “How to Build Your Own Radio
Telescope”, First Edition, 2007.
[6] http://www.radiotelesopebuilder.com/network.htm.
BIOGRAPHIES
Marjan Marbouti was born in
Dezful, Iran, in 1987. She received
the B.Sc. degree in Physics from
Dezful Branch, Islamic Azad
University, Dezful, Iran, in 2009 and
the M.Sc. degree in Physics from
Central Tehran Branch, Islamic Azad
University, Tehran, Iran, in 2013.
Currently, she is studying Ph.D. degree in Cosmology
Physics in Amirkabir University of Technology, Tehran,
Iran. Her field of interests includes radio astronomy and
designing VLF antennas and power engineering.
Mehdi Khakian Ghomi was born in
Tehran, Iran, in 1972. He received his
B.Sc., M.Sc., and Ph.D. degrees in
Physics from Sharif University of
Technology, Tehran, Iran in 1995,
1997 and 2004, respectively. He
received his Post-Doc, from IASBS,
Iran in 2006 and currently he is an
Assistant Professor in Physics Department, Faculty of
Energy Engineering, Amirkabir University of
Technology, Tehran, Iran. His field of interests cosmic
rays and astronomy physics.
Mohammad Reza Salmanpour
Paeen Afrakati was born in
Qaem Shahr, Iran, in 1988. He
received his B.Sc. degree in Hadaf
University, Sari, Iran in 2012 and
currently he is studying M.Sc. degree
in Nuclear Engineering in Amirkabir
University of Technology, Tehran, Iran. His field of
interests includes electrical machinery and power quality.
Keyvan Ghanbari was born in
Hadishahr, East Azarbaijan, Iran in
September 1988. He received his
B.Sc. degree in Theoretical Physics
from Tabriz University, Tabriz, Iran
in 2012. Currently, he is studying
M.Sc. degree in Cosmology
Engineering in Amirkabir University
of Technology, Tehran, Iran. His field of interests
includes radio astronomy and designing VLF antenna and
power engineering.
Behzad Nahavandi was born in
Bakhtaran, Iran, in 1989. He received
his B.Sc. degree in Electrical
Engineering from Kermanshah
Branch, Islamic Azad University,
Bakhtaran, Iran in 2010. His field of
interests includes radio astronomy
and designing VLF antennas power
engineering.
Le Minh Tan was born in Binh
Dinh, Vietnam, in 1982. He received
the B.Sc. degree in Physics from
Hanoi National University of
Education, Vietnam in 2004 and the
M.Sc. degree in Physics from Can
Tho University, Vietnam in 2010 and
is studying Ph.D. degree in Physics
in Ho Chi Minh University of Science, Vietnam. His field
of interests includes manufacture of physics experiments
and VLF (Very Low Frequency) technique and space
weather.