Antenna Lab 3

INTRODUCTION
What is CST Microwave Studio? CST Microwave Studio a.k.a (also known
as) CST MWS is software and a specialist tool for the 3D EM simulation of high
frequency components. CST MWS unparalleled performance is making it first
choice in technology leading R&D departments. This software also enables the fast
and accurate analysis of high frequency (HF) devices such as antennas, filters,
couplers, planar and multi-layer structures. For this laboratory experiment, we will
try using planar antenna. Planar antenna is an antenna in which all of the elements,
both active and parasitic, are in one plane. We will learn how to use and familiarize
with CST software by performing basic planar antenna simulation.
Below are some pictures of user interface of the software (whats inside the CST
software) and the design of planar antenna inside CST:
*So basically, planar antenna consists of:
i) Metal patch
ii) Dielectric Substrate

iii) Ground Plane
PROCEDURES
After open the CST Microwave Studio Software, follow the following steps:
1) Create Project
Click Create a new project
New project window will appear, create a new template. Click as
follows: MW&RF&Optical Antennas Planar Time
domain. Select the units as shown in lab module.

Then, in Settings, choose Frequency Min as 4 GHz, Frequency Max as
6 GHz. Tick all box in Monitors. Define at 5.5, 5.8, 6 GHz then click
Next.
Name template as Antenna-Planar Lab.
Click Modeling to view more details.
2) Patch Design
Click brick, click Esc button to show the dialog box. Insert as follows
in the dialog box from the lab module.
For the material, click Load Material from library under option
Material and choose Copper (annealed).
When a new dialog box appear for New Parameter, assign the value as
follows for each new parameter defined earlier such that Wp=20.43,
Lp=16.47, H=1.6, Ht=0.035
3) Substrate design and ground plane

Click brick again to design the substrate and ground plane. Fill the
following values based on the lab module.
Selection for the material is also based on the lab module.
4) Microstrip transmission feed line design

Click again brick and fill up the values and select the materials from
what given in the lab module. There are quarter wave transformer and
50 feed that need to be design.
5) Waveguide port creation

Click view to see it more clearly. One way to define the port for this
type is to enter all its coordinates numerically.
We can pick the entire end face of the microstrip line which is located
on the surface of the dielectric substrate.
After that, open the port definition dialog box (Simulation: Sources and
Loads Waveguide Port).
In there, modify the values as shown in lab module and set k as 3. Then,
click home and click the Global Properties. Change the settings as
shown in lab module.
Lastly, start the simulation and record the values.
RESULTS AND OBSERVATIONS
Simulation Result
1) Reflection Coefficient, S11
i) 5.6 GHz
Bandwidth = 5.6403 GHz 5.5519 GHz

= 0.0884 GHz
ii) 5.8 GHz
Bandwidth = 5.8020 GHz 5.7629 GHz

= 0.0391 GHz
2) Table 1
S11 Result/Parameter Initial Optimized

f 5.6GHz 5.8GHz
S11 bandwidth 0.0884 GHz 0.0391 GHz
Lp 16.47 15.80
Wp 20.43 20.43
3) Far-field Radiation pattern and Polar
Frequency:
i) 5.5 GHz
Far-field Radiation pattern:
Gain = 4.628
Radiation efficiency = 0.8641
Total efficiency = 0.6769
ii) 5.8 GHz

Gain = 3.137
iii) 6.0 GHz

Gain = 1.931
Additional Results:
VSWR:
Frequency = 5.6 GHz, VSWR = 1.7130
Cross polarization radiation pattern result (H-plane and E-plane)
Frequency = 5.6 GHz
H-plane E-plane
Frequency = 5.8 GHz
H-plane E-plane
Frequency = 6.0 GHz
H-plane E-plane
DISCUSSION
1) Discuss the use of the quarter wave length transformer.

A quarter-wave transformer is a simple impedance transformer which
is commonly used in impedance matching in order to minimize the
energy which is reflected when a transmission line is connected to a
load. Besides, the quarter-wave transformer also uses a transmission
line with different characteristic impedance.
2) Discuss the effect of increasing mesh cell size in the simulation.

Mesh cell size determine how many mesh cells are required to
discretize the computational volume. Therefore, if we increase the
mesh cell size in the simulation, the total number of mesh cells will
increase.
3) Discuss the effect of varying the some of the physical parameters towards the
reflection coefficient S11.
If we vary the physical parameter such as width and length, the
reflection coefficient S11 will change. For example, if we reduce the
length of the antenna patch, the higher the frequency of the microstrip
antenna. The smaller the size of antenna, the higher the frequency. It is
inversely proportional.
4) Discuss the advantage and disadvantage of patch antenna.
Advantages
i) Low cost and ease of manufacturing
ii) Support for both linear and circular polarization
iii) Easy to integrate with microwave integration circuis and are
efficient radiators.
Disadvantages
i) Low impedance bandwidth or narrow frequency bandwidth
ii) Low gain and sometimes have extra radiation occurs from its
feeds and junctions
iii) Size sometimes comes in both advantages and disadvantages.
CONCLUSION
Based on the laboratory experiment last week, all I can conclude is that this
experiment is carried out successfully because Ive learned how to use and
familiarize with CST software. Besides, by using this CST software, I also
understood the basic planar antenna simulation and how it works. This software is
so useful and has many features such as it can observe and analyze planar antenna
parameters. Furthermore, I learned that the size of the antenna is inversely
proportional with the frequency. For example if we want to design a higher
frequency antenna, the size of that antenna should be as small as possible. As
conclusion, this CST software is good and useful software, I hope that I can learn
more about it in the future and make a good use of it for my future undertakings.

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What are the main components of a planar antenna?

What are the main components of a planar antenna?

What are the steps to design a planar antenna using CST Microwave Studio?

What are the steps to design a planar antenna using CST Microwave Studio?

INTRODUCTION

ii) Dielectric Substrate

domain. Select the units as shown in lab module.

3) Substrate design and ground plane

4) Microstrip transmission feed line design

5) Waveguide port creation

RESULTS AND OBSERVATIONS

1) Reflection Coefficient, S11

Bandwidth = 5.6403 GHz 5.5519 GHz

Bandwidth = 5.8020 GHz 5.7629 GHz

S11 Result/Parameter Initial Optimized

3) Far-field Radiation pattern and Polar

ii) 5.8 GHz

iii) 6.0 GHz

Frequency = 5.8 GHz, VSWR = 5.6502

Frequency = 6.0 GHz, VSWR = 8.1266

Cross polarization radiation pattern result (H-plane and E-plane)

Frequency = 5.6 GHz

Frequency = 5.8 GHz

1) Discuss the use of the quarter wave length transformer.

2) Discuss the effect of increasing mesh cell size in the simulation.

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