Detailed Analysis and Design of a Logarithmic Spiral Antenna Project

This report details a student's project on the design and implementation of a logarithmic spiral antenna. The project focuses on developing a low-cost and efficient spiral antenna fed with a logarithmic uniplanar antenna and backed with a coplanar-waveguide (CPW). The report covers the project's background, objectives, and the student's specific contributions, including the design specifications, balun configuration, and simulation environment. The student employed IE3D simulation software and faced challenges related to simulation capacity, which were addressed by breaking down the antenna design into smaller parts. The report further describes the application of engineering knowledge, such as the use of baluns for CPW-to-CPS transformation and the selection of appropriate materials and dimensions to achieve desired frequencies and polarizations. The project also includes innovative approaches like creating a cavity for unidirectional pattern detection and optimizing balun design criteria. The report concludes with a project review, highlighting the student's contributions and the obtained results, including the frequency range and reflection coefficient of the antenna. The report demonstrates the student's ability to apply theoretical knowledge and practical skills in antenna design and implementation.

Career Episode 2
Competency Demonstration Report (CDR)

CE 2.1: Project Introduction
Name of the Project : Design of logarithmic spiral antenna
Geographical Location :[Please Fill]
Project Duration : [Please Fill]
Organization : [Please Fill]
Position in the Project : Team Member
CE 2.2: Project Background
CE 2.2.1: Characteristics of the Project
In case of the frequency independent antennas, the polarization, impedance and radiation
pattern are remained unchanged throughout the large domain of bandwidth. I have observed that
the frequency of the antenna remains proportional with the electrical dimension of the antenna.
Therefore, in this project I have worked for developing a los cost and efficient spiral antenna, in
this project I have fed the logarithmic uniplanar antenna and backed the design with coplanar-
waveguide. I have further conducted the simulation of the antenna design for predicting the
performance analysis in respect to the input impedance and radiation pattern for the spiral
antenna.
CE 2.2.2: Objectives developed for project
In this project I have developed the following objective for timely completion of the
project.
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 To provide the antenna specifications for developing the spiral antenna;
 To determine the required configuration for the balun design implemented in the
spiral antenna;
 To conduct the experimental and numerical analysis for the proposed prototype
model for the spiral antenna;
 To simulate the proposed antenna using appropriate simulation software;
CE 2.2.3: My area of work
I have worked in this project for the design specification of the spiral antenna. I have
developed specification and configuration of the balun for transforming the frequency of the
antenna. In addition to that, I have determined the specification and developed the simulation
environment for the performance analysis. In addition to that, I have developed the prototype
model of the antenna and developed the required chamber for the spiral model.
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CE 2.2.4: Project Group
Figure: Team Member Associated with the completion of the Project
CE 2.2.5: My responsibilities throughout the project
I had multifaceted responsibility in this project for the design and implementation of the
spiral antenna. In the initial phase of the project, I have reviewed the past studies and project that
needs to be followed for the development of the spiral antenna. I have further demonstrated the
working principle and theories of spiral antenna to the team members for providing the work
responsibility in the project. Furthermore, I have described the various parameters of the antenna
design and operations for obtaining required frequency and polarization in the spiral antenna. In
addition to that, I took the complete responsibility of communicating with the project lead and
providing regular updates about the deployment of the spiral antenna.
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CE 2.3: Distinctive Activity
CE 2.3.1: Comprehending the Theory of the project
The design of the logarithmic antenna are developed based on two significant equations
namely r1 = r0 eaϴ and r2 = r0 e a(ϴ -ϴ0). In the equations, r2 and r1 are used for demonstrating the
inner and outer radii of the spiral antenna. And r0 eaϴ and r0 e a(ϴ -ϴ0) are the inner and outer initial
radii of the antenna. In the above equations, ϴ is used for considering the angular position of the
antenna. Based on the above equations, I have developed the appropriate design parameter and
demonstrated the width between the arms for obtaining the frequency independent parameter for
antenna design. I have further used 1 to 1.5 turns for obtaining efficient radiation pattern. I have
truncated the spiral arms of the antenna for gaining lower resonant frequency of the physical
antenna. I have ensured that the axial ration of the antenna is decreased with the increased of the
frequencies for obtaining elliptical polarization.
CE 2.3.2: Engineering Knowledge and Skills applied in the project
While working in this project, I have reviewed various past studies on the design and
implementation of the spiral antenna. From the review I have learnt that circular polarization can
be obtained in the spiral antenna design where the frequencies are wither lesser or greater that
wavelength. In this project, I have provides the constant input impedance and varied the
frequency. I have worked in this project for obtaining circular polarization from the circular
antenna considering the one wavelength for electrical arm length. I have used balun for
transforming the CPW (unbalanced coplanar waveguide) for feeding the line along the CPS
(balanced coplanar strip). I have utilized my idea and knowledge about the wideband balun for
transforming the CPW to required CPS. In the design of the balun I have used Chebyshev
impedance four section transformer and ensured 0.05 of reflection coefficient that is denoted by
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Γ. In addition to that, I have utilized slotted radial patch for accomplishing smooth transition.
Moreover, I have attacked two bond wires alongside the plane of discontinuity for ensuring the
equal potential of the grown planes.
CE 2.3.3: Accomplishment and Task Performed
In this project, I have selected 0.52 m length of the arm for obtaining the appropriate 0.58
GHz of resonant frequency. I have set the impedance of the spiral antenna to be 80 ohm. Ii have
used RT/Duroid substrate for developing the balun structure having 0.785 mm thickness, 16 × 43
mm size and 10.2 of dielectric constant. I have further used IE3D as the required simulation
software for performing the analysis of the proposed antenna.
CE 2.3.4: Identified Issues and Their Solutions
Issue: in this project I have selected IE3D for simulating the proposed design for the
spiral antenna. While conducting the analysis, I have observed that effectiveness of the analysis
is significantly reduces with the increased structure of the antenna design. I have faced
significant issue in this project when I was unable to simulate the spiral antenna due t the limited
capacity of the computer and the time allocated for the project. This has created significant
technical and development issue in this project.
Solution: For eliminating the issue, I have broken down the antenna in smaller and
manageable parts. I have used different color for illustrating the different parts in the antenna
design. Through this I was able to simulate each part of the spiral antenna through detailed
design. In this project I have ensured that the increased frequency of the antenna required the
increased size of the antenna. In the initial stage I have conducted the simulation on the antenna
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with providing the frequency between 0.1 to 1.4 GHz. I have further gradually increased the
frequency during the simulation and obtain detailed results as expected.
CE 2.3.5: Plan for producing creative and innovative work
In the spiral antenna, two broad lobes are used that are perpendicular in nature with the
antenna plane. In this project, I have preferred unidirectional pattern of the antenna for detecting
the reflection of the antenna. Therefore, I have created a cavity in the design and used
polystyrene foam with 40 mm and 130 mm of thickness. I have backed the cavity of the results
of the CPW for feeding in the antenna cavity. I have used S-parameters for extending the
bandwidth of the antenna. Furthermore, I have for the applied balun approach I have optimized
the criteria for designing the required spiral antenna criteria. Apart from that, I have design 1.5
GHz and 0.8 GHz of the θ value used in the transmission filed. Through this I was successful in
obtaining appropriate frequencies with the application of the balun design. I have further met all
the required criteria essential for the designing and implementing the appropriate design o the
spiral antenna.
CE 2 .3.6: Collaborative work
I have followed and focused on developing the project with team work and collaborative
approach. I have communicated with the team members for allocating the tasks among us for
easy development and collaboration. I have designed an appropriate resource allocation and
RACI matrix for identifying and easy allocation of the responsibilities, activities and resources
required for completion of the project. In addition to that, I have initiated weekly team meetings
for providing follow up of the developed task and activities.
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CE 2.4: Project Review
CE 2.4.1: Project Overview
I was successful in implementing the spiral antenna with the application of FR-4
substrate. In addition to that, I have used RT/Duroid substrate for the design of the balun
structure. From the analysis, the required and expected results were obtained. The frequency
range of the antenna was observed between 5 GHz to 300 kHz. I addition to that, I have found
the reflection coefficient of the antenna to be higher during the simulation process.
CE 2.4.2: My contribution to work
Before working in this project, I had the practical experience that I have gained from past
projects and workshops. I have used my knowledge and skills in this project for the selection of
the required hardware components and the circuit design for the antenna. I was further associated
in this project for the prototype model development of the spiral antenna proposed. In addition to
that, I have ensured the proper quality and standard of the implementation and design throughout
the antenna design project.
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