International Journal of Engineering Trends and Technology (IJETT) – Volume 14 Number 4 – Aug 2014
Characterization of Circular Waveguide at High
Frequency
Kalpesh K. Prajapati#1, Prof. Rajesh Ishwar#2
#1
.P.G. Student, Department of Electronics and Communication
S.P.B. Patel Engineering College, Linch , Mehsana, India
#2
.Assi. professor, Department of Electronics and Communication
S.P.B.Patel Engineering College, Linch , Mehsana, India
Abstract : In the recent years there is a notable development
leap in communication system operating at Microwave
frequencies. Such a development is necessary to support a
wide variety of emerging application. In this paper the
characterization of Circular waveguide is done at high
frequency of 20 Ghz. The characteristics like E-field , H-field,
VSWR , S-parameter is observed. The Simulation is carried
out in the HFSS (High Frequency Simulation Software).
keyword: Circular waveguide, VSWR, Propagation
Constant, HFSS
I. INTRODUCTION
The circular waveguide is a transmission line which is in
the circular shape. The characterization of the circular
waveguide is done by transmitting wave from hollow
waveguide with a air or vacuum filled material. The
reflection of the wave from the wall and travelling through
the circular waveguide will demonstrate the characteristics
of the component.
Circular waveguide is the passive microwave component.
The passive Component are those component which does
not required any external power supply for its operation.
The electromagnetic waves propagating inside the
waveguide may be characterized by reflections from the
conducting walls. It is a radiating structure finds many
applications in communication system, radar, biomedical,
and both as single radiator and as coupled radiators. The
Circular waveguide is a transmission medium supports TE
and TM modes. Because of the lack of a center conductor,
the electromagnetic field supported by a waveguide can
only be TE or TM modes. For circular waveguide the
dominant mode is TE11, which has the lowest cut-off
frequency.
The HFSS is a software package analysis modeling and
analysis of 3-dimensional structures. HFSS utilizes a 3D
full wave finite element method to compute the electrical
behaviors of high frequency and high speed components.
The HFSS is more accurately characterizes the electrical
performance of components and effectively evaluates
various parameters. It helps the user to observe and
ISSN: 2231-5381
analyze various performance of electromagnetic properties
of structures such as propagation constant, characteristic
port impedance, generalized S-parameters and YParameter etc are normalized to specific port impedances,
the Eigen modes or resonances of the of the structures.
The HFSS software is designed for extracting modal
parameters by simulating passive devices. It is necessary
for designing high frequency and high speed components
used in modern electronic devices. The HFSS simulated
results are more accurate and helpful before design and
fabricating of real world components. In this paper
characteristic of the Circular waveguide is simulated
using HFSS. This analysis is much helps in the
fundamental of waveguide.
II. METHODOLOGY
Electromagnetic field can be predicted by experiment,
analysis and computation. The last mentioned technique,
otherwise known as numerical simulation, is the most
recent and rapidly advancing. Electromagnetic field, like
many other physical processes, are governed by partial
deferential equations (PDEs). Hence the numerical
methods for solving such problems can be classed with
other methods of solving PDEs, such as the Finite Element
method, Method of Moments and Finite Deference
method. Every modeling technique has some strengths and
some weaknesses.
Electromagnetic simulators can give very accurate
solutions for microwave circuits with ideal conductors.
When the conductors are non-ideal, accurate results may
still be obtained in many cases by specifying material
parameters or surface impedances. However, for structures
in which the penetration depth of the field into the
conductors is of the same order as the conductor thickness,
considerable error can occur.
The finite element method is one of the most successful
frequency
domain
computational
methods
for
electromagnetic simulations. The method’s main
advantage is its capability to treat any type of geometry
and material in homogeneity without a need to alter the
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International Journal of Engineering Trends and Technology (IJETT) – Volume 14 Number 4 – Aug 2014
III. SIMULATION
formulation or the computer code. That is, it provides
geometrical fidelity and unrestricted material treatment.
A circular waveguide is a tubular , circular conductor. A
plane wave propagating through a circular waveguide
results in transverse electric (TE) or transverse magnetic
(TM) mode.
The design of the circular waveguide is created in the
HFSS simulation software. The driven model solution is
selected for the simulation. the design in the HFSS is as
below in Fig. 2. The waveguide is filled with the vacuum
and assigned boundary condition is finite conductivity.
The excitation is provided at both the wave port.
Fig. 1 Coordinates of a Circular waveguide
It is commonly assumed that the waves in a circular
waveguide are propagating in the positive z direction. The
modes in the circular guide are characterized by
= 0.This means that the z component of the magnetic
field
must exist in the guide in order to have
electromagnetic energy transmission. A Helmholtz
equation for
in a circular guide is given by
∇
=
(1)
Fig.2 Circular waveguide in HFSS
The Design of circular waveguide with the inner diameter
of 2.383 cm (0.938 in.) in HFSS. The outer wall of the
waveguide is assigned a boundary condition called finite
conductivity or perfect E. with this assumption, the port is
defined within a waveguide. The frequency range for the
simulation is 0-20 GHZ.
IV. RESULT
Its solution is given by
(
=
)cos( ∅)
The output for the different modes of the port are seen in
the simulation result. The result for the
, for the mode
1 and for the
for
mode
2
are
seen
in
the simulation
,
analysis.
(2)
Which is subject to boundary condition.
. The
modes in the circular guide are characterized
by
= 0.However, the z component of the electric
field
must exist in order to have energy transmission in
guide. Consequently, the Helmholtz equation for
in a
circular guide is given by
∇
=
(3)
Its solution is given by
=
(
)cos( ∅)
Fig.3
(4)
,
mode 1.
Which is subject to boundary condition.
ISSN: 2231-5381
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International Journal of Engineering Trends and Technology (IJETT) – Volume 14 Number 4 – Aug 2014
Fig.3
,
Mode 2
Fig.6 H field Pattern
The output of the VSWR plot for the circular waveguide
indicates the reflection of travelling wave in the
waveguide. The standing wave ratio for the circular
waveguide from the simulation is as below.
VSWR
HFSSDesign1
1.0035
ANSOFT
Curve Info
VSWR(w aveport1:1)
Setup1 : Sw eep
VSWR(w aveport2:2)
Setup1 : Sw eep
1.0030
1.0025
V. CONCLUSION
The characterization of the circular waveguide in the high
frequency is done in the simulation software HFSS. The
output results for the different modes , VSWR and field
shows that waveguide is working perfectly at this
frequency. The waveguide is ready to work in the open
environment for its different application.
ACKNOWLEGMENT
Y1
1.0020
1.0015
1.0010
1.0005
1.0000
0.00
2.50
5.00
7.50
10.00
Freq [GHz]
12.50
15.00
17.50
20.00
To present this paper I would like to thanks Prof. J.C.
Prajapati for his continues motivation and guidance. I
would also like to thanks the Laboratory assistants of
Saffrony College for help in using the lab component very
effectively.
REFRENCES
Fig.4 VSWR plot
The field pattern for the travelling E-filed and H-filed
wave in the waveguide.
Fig.5 E Field Pattern
ISSN: 2231-5381
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