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Transcript of Optical & Microwave Communications
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Jawaharlal Nehru Engineering College
Laboratory Manual
Optical & Microwave Communications
For
Final Year Students
Manual made by
Prof.S.D.Jadhav
Author JNEC, Aurangabad
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Technical Document
This technical document is a series of Laboratory manuals of Electronics and
Telecommunication Department and is a certified of Jawaharlal Nehru Engineering
College. The care has been taken to make the document error free. But still if any error
is found, kindly bring it to the notice of subject teacher and HOD.
Recommended by
HOD
Approved by,
Principal
Copies:
1. Departmental Library
2. Laboratory
3. HOD
4. Principal
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FOREWARD
It is my great pleasure to present this laboratory manual for final year students for the
subject of Optical fiber and microwave Communications keeping in view the vast
coverage required for visualization of concept of Optical fiber and Microwave
Communications.
As a student, many of you may be wondering with some of the questions in your mind
regarding the subject and exactly what has been tried to answer through this manual.
Faculty members are also advised that covering these aspects in initial stage itself,will
greatly relieve them in future as much of the load will be taken care by the enthusiasmenergies of the students once they are conceptually clear.
H.O.D
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LABORATORY MANUAL CONTENTS
This manual is intended for the Final Year students of Engineering in the subject of
O&MC. This manual typically contains practical/Lab sessions related O&MC covering
various aspects of the subject to enhance understanding.
Students are advised to go thoroughly through this manual rather than only topics
mentioned in the syllabus as practical aspects are the key to understand and
conceptual visualization of theoretical aspects covered in the books
Good Luck for your enjoyable Laboratory sessions.
Prof.S.D.Jadhav
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DOs and Donts in Laboratory:
1. Do not handle the equipment without reading the instructions/Instruction manuals.
2. Read carefully the power ratings of the equipment before it is switched on. ForIndian equipments, the power ratings are normally230V/50Hz.If you have equipmentwith115V/60Hz ratings do not insert power plug, as our normal power supply is230V/50Hz,Which will damage the equipment.
3. Observe the type of sockets to avoid mechanical damage.
4. Do not forcefully place the connectors.
5. Strictly observe the instructions given by the teacher/lab instructor..
Instruction for Laboratory Teachers:
1. Lab work completed during prior session should be corrected during the next lab
session.
2. Students should be guided and helped whenever they face difficulties.
3. The promptness of submission should be encouraged by way of marking and
evaluation patterns that will benefit the sincere students.
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SUBJECT INDEX
Lab Experiments
1. Study Optical fiber
2. Study Optical fiber Connectors and Splices
3. Study Optical Time Domain Reflectometer (OTDR)
4. Study Sources of light for Optical fiber
5. Study the various UHF components
6. Measurement of transmission line characteristics
7. Study of Gunn diode and plotting its VI characteristics
8. Study Microwave TEEs
9. Study of Microwave Antennas
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Experiment No.1
Study of Optical Fiber
Aim: To study Optical fiber.
Apparatus: Optical fiber, Cutter, light source, etc
Theory:
An optical fiber (or fiber) is a glass or plastic fiber that carries light along its length. Fiber
optics is the overlap of applied science and engineering concerned with the design and
application of optical fibers. Optical fibers are widely used in fiber-optic communications,
which permits transmission over longer distances and at higher bandwidths (data rates)
than other forms of communications. Specially designed fibers are used for a variety of
other applications, including sensors and fiber lasers. Light is kept in the core of the
optical fiber by total internal reflection. This causes the fiber to act as a waveguide.
Fibers which support many propagation paths or transverse modes are called multi-
mode fibers (MMF), while those which can only support a single mode are called single-
mode fibers (SMF). Multi-mode fibers generally have a larger core diameter, and are
used for short-distance communication links and for applications where high powermust be transmitted. Single-mode fibers are used for most communication links longer
than 550 meters (1,800 ft).
Principle of operation
An optical fiber is a cylindrical dielectric waveguide (non conducting waveguide) that
transmits light along its axis, by the process of total internal reflection. The fiber consists
of a core surrounded by a cladding layer, both of which are made of dielectric materials.
To confine the optical signal in the core, the refractive index of the core must be greater
than that of the cladding. The boundary between the core and cladding may either be
abrupt, in step-index fiber, or gradual, in graded-index fiber
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Total internal reflectionTotal internal reflection is an optical phenomenon that occurs when a ray of light strikes
a medium boundary at an angle larger than a particular critical angle with respect to the
normal to the surface. If the refractive index is lower on the other side of the boundary,
no light can pass through and all of the light is reflected. The critical angle is the angle
of incidence above which the total internal reflection occurs. When light traveling in a
dense medium hits a boundary at a steep angle (larger than the "critical angle" for the
boundary), the light will be completely reflected. This effect is used in optical fibers to
confine light in the core. Light travels along the fiber bouncing back and forth off of the
boundary. Because the light must strike the boundary with an angle greater than the
critical angle, only light that enters the fiber within a certain range of angles can travel
down the fiber without leaking out. This range of angles is called the acceptance cone of
the fiber. The size of this acceptance cone is a function of the refractive index difference
between the fiber's core and cladding.
In simpler terms, there is a maximum angle from the fiber axis at which light may enter
the fiber so that it will propagate, or travel, in the core of the fiber. The sine of this
maximum angle is the numerical aperture (NA) of the fiber. Fiber with a larger NA
requires less precision to splice and work with than fiber with a smaller NA. Single-mode
fiber has a small NA.
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Fig1.Cross Section of Optical Fiber
Special-purpose fiber
Some special-purpose optical fiber is constructed with a non-cylindrical core and/or
cladding layer, usually with an elliptical or rectangular cross-section. These include
polarization-maintaining fiber and fiber designed to suppress whispering gallery mode
propagation.
Photonic crystal fiber is made with a regular pattern of index variation (often in the formof cylindrical holes that run along the length of the fiber). Such fiber uses diffraction
effects instead of or in addition to total internal reflection, to confine light to the fiber's
core. The properties of the fiber can be tailored to a wide variety of applications.
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Materials
Glass optical fibers are almost always made from silica, but some other materials, such
as fluorozirconate, fluoroaluminate, and chalcogenide glasses, are used for longer-
wavelength infrared applications. Like other glasses, these glasses have a refractiveindex of about 1.5. Typically the difference between core and cladding is less than one
percent.
Properties of Optical Fiber.
1.Numerical Aperture of any type of fiber is defined as:
where n1 =is the refractive index along the central axis of the fiber(core).
n 2= refractive index of cladding
2. Attenuation
3. Dispersion
3. Fiber strength
4. Band width parameters
5.Rise Time
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Applications and Advantages
1. Optical fiber can be used as a medium for telecommunication and networking
because it is flexible and can be bundled as cables.
2. It is especially advantageous for long-distance communications, because light
propagates through the fiber with little attenuation compared to electrical cables. This
allows long distances to be spanned with few repeaters.
3. Additionally, the per-channel light signals propagating in the fiber can be modulated
at rates as high as 111 gigabits per second,] although 10 or 40 Gb/s is typical in
deployed systems.
4. Each fiber can carry many independent channels, each using a different wavelength
of light (wavelength-division multiplexing (WDM)).
5. The net data rate (data rate without overhead bytes) per fiber is the per-channel data
rate reduced by the FEC overhead, multiplied by the number of channels (usually up to
eighty in commercial dense WDM systems as of 2008). The current laboratory fiber
optic data rate record, is multiplexing 155 channels, each carrying 100 Gbps over a
7000 km fiber.
Conclusion:-Hence Optical fiber is studied in detail.
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Experiment No.2
Study of Optical Fiber Connectors and Splices
Aim: To study Optical fiberConnectors and Splices
Apparatus: Optical fiber, Connectors and splices.
Theory:
An optical fiber connectorterminates the end of an optical fiber, and enables quicker
connection and disconnection than splicing. The connectors mechanically couple and
align the cores of fibers so that light can pass. Most optical fiber connectors are spring-
loaded: The fiber end faces of the two connectors are pressed together, resulting in a
direct glass to glass or plastic to plastic, respectively, contact, avoiding any glass to air
or plastic to air interfaces, which would result in higher connector losses.
Connectorization and Splicing of optical Fiber.
In any fiber optic system, one will find the need of splices and connectors. Splices are
required during i9nstallation and again during services, if the cables are damaged and
fibers are broken, Connectors are invariably used to connect fiber to the terminal
equipment. Each splice or connector gives rise to additional attenuation and the need to
minimize such losses requires a careful preparation of the ends of the fiber. Low losses
are obtained only if the fiber ends are clean, smooth and perpendicular to the fiber axis.
CONNECTORIZATION:-
It is the process of terminating the fiber by a connector. Normally a source and a
detector are mounted inn a standard bulkhead, into which the fiber of the system.
Having connector at the end, is plugged. Such an arrangement permits individual units
and components to be tested separately and replace if necessary. Moreover this
arrangement also allows maximum coupling of light.
Many different designs of connectors have been developed. Most use a female for fiber
alignment, although some designs use three spheres to centre the fiber and a double
cone to align the connectors. Some of the more sophisticated types intended for use in
high speed where back reflections must be minimized, allow physical contact between
the two.
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SMA connector is commonly used with multimode fibers. It has a 9mm long ferrule with
a precision bore designed to match the cladding diameter and a standard SMA
threaded sleeve for connection. A typical insertion loss is in the region of1dB initially,
but mechanical wear &tear of the fiber during its life involves thousands of
disconnections and re connections causing losses to increase.
The ST connector is intended for use with multimode fibers. It is relatively easy to
terminate and employ a bayonet coupling collar somewhat similar to BNC co-axial
connector. Typical insertion losses of 0.5dB can be obtained in clean conditions.
Some relatively inexpensive, bi-conical, plastic, snap-in connectors have been
developed, of which the type SC is one. Another standard is the two fiber connector
specified for the FDDI high capacity LAN.
Note:- Draw the diagram of Lens type Connector and ferrule type connector
Conclusion: Thus, Fiber connector and splices is studied successfully.
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Experiment No.3
Study of OTDR
Aim: To study Optical Time Domain Reflectometer (OTDR)
Theory:
The OTDR or backscatter method utilizes the light scattered in the fiber by Rayleigh
scattering.
Figure below shows the block diagram of operating principle of OTDR.
Coupler Fiber
Fig 1. Block diagram of operating principle of OTDR
Pulsed Laser
Box Car
Integrator
APD Photodetector
Log Amplifier Chart Recorder
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This Technique provides measurement of the attenuation on an optical fiber link.
A light pulse is launched into the fiber in the forward direction from an injection laser
using either directional coupler or a system of external lenses using a beam splitter. The
backscattered light is detected using an Avalanche Photodiode receiver which drives an
integrator in order to improve the received signal to noise ratio by giving arithmetic
average over a number of measurements taken at one point within the fiber. This is
necessary as the received optical power from a particular point along the fiber is very
low. The signal from the Integrator is fed through a logarithmic amplifier and averaged
measurements for location for successive points within the fiber are plotted on a strip
chart recorder. This provides location-dependant attenuation values which gives an
overall picture of the optical loss down the fiber link.
Conclusion: Thus the Operating principle of OTDR is studied in detail .
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Experiment No.4
Sources of light for Optical fiber
Aim: To study Sources of light for Optical fiber
Theory:
Optical source is often considered to be the active component of an OFC system.
Its function is to convert electrical energy in the form of current into optical energy, in
efficient manner into the fiber.
Three main types of optical fibers sources are
1. Wideband continous spectra sources(incandescent lamps)
2. Monochromatic incoherent sources (Light Emitting Diodes)
3. Monochromatic coherent sources (Lasers)
For optical Fiber communications LEDs and LASERS are preferred sources.
1. Light Emitting Diodes:
Construction and working principle:
The LED consists of an encapsulated chip of semiconductor diode with a suitable lens.
The length of Anode terminal is greater than cathode terminal. LEDs are based on the
semiconductor diode. When the diode is forward biased (switched on), electrons are
able to recombine with holes and energy is released in the form of light. This effect is
called electroluminescence and the color of the light is determined by the energy gap of
the semiconductor. The LED is usually small in area (less than 1 mm 2) with integrated
optical components to shape its radiation pattern and assist in reflection.
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Fig 1.Working Principle of LED
Material for LED
In case of LED different materials are used to get the radiation in infrared region and in
the visible region. To get radiation in infrared region Ga As material is used Sometimes
the combination Ga As with indium and aluminium is used. It gives the wavelength as
follows:
In Ga As------8500 Angstrom
Al Ga as-------9000 Angstrom
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Advantages of LED
1. They are small in size and light in weight.
2. They are mechanically rugged and have low operating temperature.
3. No complex driving circuitry is required.
4. Have high switching speed and are available in different colours.
5. Linearity is more and compatible with integrated circuits.
Disadvantages of LED
1. Output power gets affected by the temperature variation.
2. Quantum efficiency is low.
3. Gets damaged because of overvoltage and over current.
Fig 2.Different types of LED
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2. LASER: (Light Amplification by Stimulated Emission of Radiation)
A laser (Light Amplification by Stimulated Emission of Radiation)is a device that emits
light (electromagnetic radiation) through a process called stimulated emission. Laser
light is usually spatially coherent, which means that the light either is emitted in anarrow, low-divergence beam, or can be converted into one with the help of optical
components such as lenses. More generally, coherent light typically means the source
produces light waves that are in step. They have the same frequencies and identical
phase.
ABSORPTION, SPONTANEOUS AND STIMULATED EMISSION
In general, when an electron is in an excited energy state, it must eventually decay to a
lower level, giving off a photon of radiation. This event is called spontaneous emission,
and the photon is emitted in a random direction and a random phase. The average time
it takes for the electron to decay is called the time constant for spontaneous emission,
and is represented by t. On the other hand, if an electron is in energy state E2, and its
decay path is to E1, but, before it has a chance to spontaneously decay, a photon
happens to pass by whose energy is approximately E24E1, there is a probability that
the passing photon will cause the electron to decay in such a manner that a photon is
emitted at exactly the same wavelength, in exactly the same direction, and with exactly
the same phase as the passing photon. This process is called stimulated emission.
Absorption, spontaneous emission, and stimulated emission are illustrated in figure
.Now consider the group of atoms shown in figure below. All begin in exactly the same
excited state, and most are effectively within the stimulation range of a passing photon.
We also will assume that t is very long, and that the probability for stimulated emission
is 100 percent. The incoming (stimulating) photon interacts with the first atom, causing
stimulated emission of a coherent photon these two photons then interact with the nexttwo atoms in line, and the result is four coherent photons, on down the line. At the end
of the process, we will have eleven coherent photons, all with identical phases and all
traveling in the same direction. In other words, the initial photon has been amplified by
a factor of eleven. Note that the energy to put these atoms in excited states is provided
externally by some energy source which is usually referred to as the pump source.
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Fig 3. Absorbtion, Spontaneous emission and stimulated emission mechanism
POPULATION INVERSION
Atomic energy states are much more complex than indicated by the description above.
There are many more energy levels, and
each one has its own time constants for decay. The four-level energy diagram shown in
figure 4. is representative of some real lasers. The electron is pumped (excited) into an
upper level E4 by some mechanism (for example, a collision with another atom orabsorption of high-energy radiation). It then decays to E3, then to E2, and finally to the
ground state E1. Let us assume that the time it takes to decay from E2 to E1 is much
longer than the time it takes to decay from E2 to E1. In a large population of such
atoms, at equilibrium and with a continuous pumping process, a population inversion
will occur between the E3 and E2 energy states, and a photon entering the population
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will be amplified coherently.
Fig.4 Amplification by stimulated emission
Advantages of LASER over other Light Sources:
1. LASER light has narrow spectral bandwidth.
2. Light is coherent and monochromatic
3. LASER light has good directionality.
4. More percentage of the LASER light is in the visible range as compared to
conventional lamps.
5. LASER has high quantum efficiency and high modulation rate.
6. LASERS are point source of light.
7. LASER has excellent stability.
8. LASER light can be modulated externally or it has ability of direct modulation.
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Types of LASERs
According to the type of material used for the formation of LASER beam, the LASERs
are classified as the solid state laser, gaseous laser, power lasers and semiconductor
LASERs.
A] Solid State LASERS
1. Ruby Laser
2. Nd: YAG Laser
B] Semiconductor LASER
C] Gas LASERs
1. Helium-Neon Lasers
2. Carbon Dioxide Laser
Conclusion: Thus, sources of light are studied in detail.
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Experiment No.5
Study Of various UHF components
Aim: To study the various UHF components.
List of Components:-
1) Rectangular wave guide2) Circular wave guide3) Wave guide stand4) Flanges5) Fixed attenuator6) Micrometer type frequency meter7) Broad band tuned probe8) Wave guide matched detector mount9) Wave guide detector mount (tunable)10) Precision slide screw tuners11) Klystron mount12) Three port ferrite circulator13) E-H tuners14) H plane Tee15) E plane Tee16) Directional coupler17) Isolator18) Match termination19) Horn antenna20) Sectoral horn antenna
21) Pyramidal antenna22) Wave guide twist23) Gunn oscillator24) PIN modulator25) VSWR meter26) Klystron power supply27) Gunn power supply
Theory: - Following information regarding the component should be written. Modelname and frequency range. Draw the diagram of each component Write specification ofeach component as given in the manual. Write application of each Component.
Conclusion: - Thus studied UHF components.
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Experiment No.6
Relationship between frequency of oscillation & repeller voltage ofReflex klystron
Aim:- To verify relationship between frequency of oscillation & repeller voltage ofReflex klystron.Apparatus: Reflex Klystron, Klystron power supply, Isolator, frequency meter,Variable attenuator, Detector mount, VSWR meter, BNC cable.
Block Diagram:-
Theory:-The reflex klystron make the use of velocity modulation to transform a
continues electron beam in to microwave power. Electron emitted from the cathode are
accelerated and passed through the positive resonator toward negative reflector, which
retard and finally reflects electron and electron return back through the resonator.
Suppose an hi field exist between the resonator .The electron traveling forward will be
accelerated or retarded .As the voltage at the resonator change in amplitude. The
accelerated electron leave the resonator at the increased velocity and the retarded
electron leave at the reduced velocity .The electrons leaving the resonator will need
different time to return due to change in velocities .As a result returning electron group
together in bunches. As the electron bunches pass through resonator they interact with
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voltage at resonator grids. If the bunches pass the grid at such time that the electrons
are slowed down by the voltage energy will be delivered to the resonator and klystron
will oscillate. The frequency is preliminary determined by the dimension of resonant
cavity. Hence by changing the volume of resonator, mechanical tuning range of klystron
is possible. Also a small frequency change can be obtained by adjusting the
reflector voltage. This is called electronic tuning.
Observation: -Beam voltage=
Beam current=
Repeller voltage=
Repeller voltage Frequency
Procedure:-
1) Connect the equipment &component s as shown in the figure
2) Set the variable attenuator to around zero position & set the range switch of
VSWR meter to 40-db positions.
3) Anti-clockwise direction, repeller voltage knob to minimum position.
4) On the klystron power supply, VSWR meter &cooling fan .Set the beam voltage
to 250v and limiting beam current to less than
5) Gradually increase repeller voltage &look for sudden deflection in VSWR
meter.
6) Note the corresponding frequency with the help of frequency meter. Also note
the repeller voltage.
7) Slightly vary the repeller voltage on either side of this reading. Note the
corresponding variation of the frequency.
8) Find the tuning range after plotting the 3db points on the repeller voltage vs.power o/p graph.
Conclusion: - Thus, we find tuning range for two widely different repeller voltages.
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Experiment No.7
Gunn diode & its characteristics
Aim: - Study of Gunn diode and plot VI characteristics of Gunn diode.
Apparatus:- Reflex Klystron ,Klystron power supply ,Isolator ,frequency meter, Variable& variable attenuator, Detector mount, VSWR meter, BNC Cable Matched load E plane,H plane & Magic Tee.
Block Diagram:-
Fig 1.Set for study of a Gunn Diode Characteristics
Theory:-
The Gunn oscillator is based on negative differential conductivity effect in
bulk semiconductors which has two conduction band minima separated by an energy
gap .A disturbance at cathode gives rise to high field region which travels towards the
anode .When this high field domains reaches the anode, it disappears and another
domain is formed at the cathode and starts moving anode and so on. The time required
for domain to travel from cathode to anode gives oscillation frequency.
A uniform type of uniform type of Gunn diode with same contact as the end surface.
Above some critical voltage current becomes function of time .It was discovered by J B
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Gunn. It uses bulk property of semiconductor only. So it must be associated with
electron rather than holes .The voltage applied is proportional to the sample length and
hence electric field is expressed in v/m.
When DC voltage is applied across the side of Gunn diode, cadmium
ferrite in -ve resistance property across at particular voltage range value .As the applied
potential increases i.e. greater than electric field higher electron present, hence higher
current across the line in short time so acceleration occur in microwave range. Actually
Frequency of oscillation in determined the time so acceleration occurs in microwave
range. Actually frequency of oscillation is determined the time that the bunches of
electron form and arrive at the end.
Procedure: -
1) Switch on the Gunn power supply.
2) Adjust the bench to get maximum o/p waveform.
3) By making voltage initially zero note down the current.
4) Plot the graph of V and I
Observation:-
1. Beam voltage=
2. Beam current=
Conclusion: - Thus the V-I characteristics of Gunn diode is studied.
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Experiment No.8
Study of Microwave TEE i.e. E plane, H plane & Magic Tee.
Aim: -To measure the power distribution of various magic Tee i.e. E plane, H plane &
Magic Tee.Apparatus: - Reflex Klystron, Klystron power supply, Isolator, frequency meter,Variable & variable attenuator, Detector mount, VSWR meter BNC, Cable Matched loadE plane, H plane & Magic Tee.
Theory:-Wave-guide Tees are used for connecting a branch section of wave-guide in series or
parallel with the main wave-guide. Tees are also be used as power divider field.
1) Input VSWR- Value of SWR corresponding to each port as a load to the line while
other ports are terminated in matched load.
2) Isolation- The isolation between E and H arm is defined as the ration of the powersupplied by the generator connected to the E port 4 to the power detected at H arm port
3 Isolation=10 log10P4/P3
3) Coupling coefficient- It is defined as Cij=10 _/20
Where _ is attenuation /isolation in dB when it is input arm and j is output arm
Thus _= 10 log Pi/Pj
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Where Pi is power delivered to arm i and Pj is power detected at j arm
E plane Tee- Model 6031 E plane Tee is a type T junction & consist of 3 section wave
guide joint together in order to divide & compare power levels .The signals entering
first part of the P junction will be equally divided at 2nd 3rd port of magnitude but
opposite in direction.
H plane Tee-Model 3065 H plane TEE are shunt type T-junction that is used in
conjunction with VSWR meter, Frequency meter &other detector devices.
Magic Tee Model 3045 E-H consist of section of wave-guide with both series &
shunt wave-guide are mounted at exact mid point of the main arm. This becomes four
terminal devices where one terminal is isolated from the i/p. VSWR of 1.40 over +-
15%freq range. This is achieved by inserting &connecting piece with stub.
Procedure: -
H-plane Tee: -
a) Give i/p at port 1
b) Observe o/p on VSWR meter at port 2&3.
E plane Tee
a) Give i/p at port 1.
b) Observe output at port
Magic Tee
a) Give i/p at port 1.
b) Observe the output at port 2,3&4
c) Give i/p at port 4.
d) Observe the o/p at port 1,2&3.
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Observation:-Beam voltage=
Beam current=
Repeller voltage=
a) H plane Tee
1. Input at port 1=
2. Output
At port 2=
At port 3=
b) E plane Tee
1. Input at port 1=
2. Output
At port2=
At port 3=
c) Magic Tee
1. Input at port 1=
2. Output
At port 2=
At port 3=
At port 4=3. Input at port 4=
4. Output
At port 1=
At port 2=
At port 3=
Conclusion:-Discuss the power distribution in each Tee.
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Experiment No.9
STUDY OF ANTENNAS
Aim: -To study the various antennas.
Theory:-
Antennas are used at all frequency but in actual practice the frequency on which it
operates depends on its shape to the large extent.
Antenna types are:-
1) Horn antenna- A horn antenna may be regarded as a flared out or open out wave
guide A wave guide is capable of radiating in to open space provided the same is
excited at one end and open at other end. However the radiation is much greater
through wave-guide than the two-wire transmission the line in waveguide is small
in portion of incident wave is radiated and large portion is reflected back by the
open circuit.
2) Parabolic reflector or microwave dish- A parabola is a two-dimensional plane
curve .A practical reflector is a three dimensional curved surface. Therefore
rotating a parabola about its axis .The surface so generated is called as
Parabolic Which is also called as Microwave Dish or Parabolic Reflector formspractical reflector. Parabolic produces a parallel beam of circular cross section
because the mouth of parabolic is circular.
3) Hertz antenna- It is also a half wave dipole antenna .The dipole antenna dates
back to the early half RF experiments in the center so that RF power can be
applied to it .One can think of the half wave dipoles an open circuited
transmission line that has been spread out so that the transmission line that has
been spread out so that transmission can be spread out in space .A dipole can
be of any length commonly is just under wavelength long.
Conclusion: - Thus the different antennas are studied.
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Quiz on the subject
Q1. What is reflex Klystron?
Q2. What are disadvantages of reflex klystron?
Q3.What are applications of klystrons?
Q4.Define directional coupler.
Q5. What are performance characteristics of directional coupler?
Q6.What are different types of Tee?
Q7.What do you mean by Magic Tee?