A rectangular patch antenna design is presented that operates at 10 GHz. The antenna consists of a rectangular metallic patch on top of a dielectric substrate with a ground plane. Quarter-wave transformer impedance matching is used between the microstrip feedline and patch to address impedance mismatching. Key dimensions of the patch and matching circuit are calculated and optimized in simulation software. Simulation results show the antenna resonates at 10 GHz with 25dB efficiency and has typical electric and magnetic field distributions and radiation pattern for a rectangular patch antenna.

1. Design of a Rectangular Patch Antenna

2. ➢ The easiest antenna description can be given as a metallic implement radiating or
receiving radio waves.
➢ The IEEE defines an antenna as meaning for either radiates or receives radio waves[1].
➢ Antennas were used to be demonstration of the electromagnetic wave transmission in early
1890s, so it could be said that there were only a few antennas in the world.
➢ Antennas has started being a fundamental part of our daily lives by World War II. Now, even an
average person carries an antenna in his/her pocket thanks to mobile phones [1].
General Antenna Description
[1] P. J. Bevelacqua, “antenna-theory,” 2015. [Online]. Available: http://www.antenna-theory.com/intro/main.php. [Accessed 05 Nov

3. ➢ Below figure depicts a Thevenin equivalent circuit in transmission line for the antenna system.
➢ An ideal generator is used as a source, ZC stands for characteristic impedance while ZA represents a load.
➢ The conduction is represented by the load resistance RL . Radiation resistance is represented by Rr .
➢ Lastly, antenna radiation is associated with the imaginary part of the impedance is represented by XA [2].
➢ There are various antenna types with different purposes.
➢ These are can be listed like array, reflector, lens, aperture, wire and microstrip so on.
➢ Mainly, throughout this presentation microstrip patched antenna has been studied.
General Antenna Description
• Thevenin equivalent circuit for the
antenna in transmitting mode[2].
[2] C. A. Balanis, ANTENNA THEORY ANALYSIS AND DESIGN, New Jersey. Published: WILEY, 2005.

4. ➢ Journey for the microstrip antennas has started in 1970s for spaceborne applications. After that,
governmental and commercial applications help to keep its popularity.
➢ A metal patch on a grounded substrate are main structures to build a microstrip antenna.
➢ Usually, rectangular or circular configurations are preferred thanks to their easy analyse and
fabrication. Besides these specifications, microstrip antennas are being chosen because of their
simple and cheap fabrication by modern printed-circuit technology and compatibility with MMIC
designs.
➢ Several ways are being applied as feeding techniques on microstrip patch antennas. These
techniques are sort like inset feeding, coaxial cable/probe feeding, coupled(indirect)feeding and
aperture feeding.
➢ Additionally, quarter-wavelength transmission line technique can be applicable for impedance
matching while using microstrip transmission line to feed antenna.
➢ The last technique has been applied through the design of the antenna which operates 10 GHz during
this presentation.
➢ Microstrip design and impedance matching with quarter-wavelength transmission line technique will
be investigated either theoretically and practically next slides.
Microstrip Antenna
[2] C. A. Balanis, ANTENNA THEORY ANALYSIS AND DESIGN, New Jersey. Published: WILEY, 2005.

5. Rectangular Patched Antenna Design
➢ Because of the fringing effect, antenna patch becomes larger than its physical dimension.
➢ It is demonstrated for the principle E-plane (xy-plane). Therefore, patch dimension is extended
by ΔL [15].
• Physical lengths of the patch [15].
∆𝐿
ℎ
= 0.412
(𝜀 𝑟 + 0.3)(
𝑊
ℎ
+ 0.264)
(𝜀 𝑟 − 0.258)(
𝑊
ℎ
+ 0.8)
➢ ΔL is a function of the relative permittivity constant as it is seen above
equation.
➢ The effective length will be calculated related to extension for the
dominant TM010 mode without fringing effect. So,
𝐿 𝑒𝑓𝑓 = 𝐿 + 2∆𝐿
➢ The microstrip antenna’s resonant frequency:
𝑓𝑟 =
1
2𝐿 𝑒𝑓𝑓 𝜀 𝑒𝑓𝑓 𝜇0 𝜀0
=
1
2(𝐿 + 2∆𝐿) 𝜀 𝑒𝑓𝑓 𝜇0 𝜀0
= 𝑞
1
2𝐿 𝜀 𝑟 𝜀0 𝜇0
= 𝑞
𝜗 0
2𝐿 𝜀 𝑟
• Where the speed of light is 𝜗0 .
• The fringe factor is represented as q [2].
[2] C. A. Ballanis, “Microstrip Antennas,” in ANTENNA THEORY ANALYSIS AND DESIGN, NJ, Wiley, 2005, pp. 810-826.

6. Design Process
➢ If the specified information’s about the substrate relative permittivity constant, the resonant frequency and
the substrate thickness are provided, the design layout are done by following:
● Define: εr, h, fr (in Hz)
● Calculate: W, L
Design Outline:
1.
𝑊 =
1
2𝑓𝑟 𝜇0 𝜀0
2
𝜀 𝑟+1
=
𝜗0
2𝑓𝑟
2
𝜀 𝑟+1
A good radiation efficiency will be led by W.
2. Determine the effective dielectric constant.
3. Determine the extension of the length, ΔL.
4. Determine the actual length of the patch, L.
𝐿 =
1
2𝑓𝑟 𝜀 𝑒𝑓𝑓 𝜇0 𝜀0
− 2∆𝐿
➢ Design Parameters:
Resonant frequency : 10GHz
Dielectric Constant : 3.45 (ISOLA-IS680-345 )
Substrate Tickness :0.76 mm (ISOLA-IS680-345 )
[2] C. A. Ballanis, “Microstrip Antennas,” in ANTENNA THEORY ANALYSIS AND DESIGN, NJ, Wiley, 2005, pp. 810-826.

7. Design Process
➢ The resonant frequency, dielectric constant and substrate thickness are provided. Therefore, process should be
started by the determination of the width, W, and length, L, of the rectangular patch.
➢ Design outline has to be followed to get some results about the size of the patch before the implementation
through CST MWS software.
The rectangular patch and microstrip line implementation have been done by following steps:
● Define template – Antenna-Planar
● Define material for the substrate ISOLA-IS680-345.
● Load COPPER from material library
● Define brick for substrate
● Define ground plane
● Define brick for rectangular patch
● Define brick for microstrip line
● Add rectangular patch and microstrip line by Boolean add shapes function
● Define Waveguide Port 1
● Define frequency range, background and boundaries
● Define field monitors: E-field, H-field, Far fields
● Set parameters for Transient Solver

8. Design Results
➢ After formula implementation W and L were obtained as
10.05mm and 7.78mm respectively.
➢ Such that results may not provide desired result in software, so
the geometry has been drawing at first as it is seen .
➢ Then, parameter optimization has been implemented thanks to
CST MWS.
Width Length
Calculated Results 10.05mm 7.78mm
Optimized Results 13.02mm 7.3 mm
• Size of patch.
Rectangular Patch
Microstripline
ISOLA Substrate

9. Design Results
➢ It is seen that there is an issue on resonance frequency resulting from impedance mismatching.
Impedance matching has a crucial impact on antenna characteristics as it is seen below figure
that the antenna does not resonate at 10 GHz.
➢ There are some techniques to be applied in order to solve this issue.

10. The Quarter-Wave Transformer
➢ Fortunately, the quarter-wave trans formator is a useful circuit to match impedance between feeding line and patch
itself.
➢ Another fact, quarter-wave transformer technique offers an easy implementation on both software and fabrication.
➢ Let’s take a look at the impedance matching problem from the impedance viewpoint.
➢ The circuit shows a quarter-wave
matching transformer.
➢ It is assumed that feedline
characteristic impedance Z0 and the
load resistance RL and are given.
➢ The connection between these two configurations are done by a lossless piece of
transmission line of characteristic impedance Z1 with a length λ/4.
➢ What it is required through this circuit is matching the load to the Z0 line by using λ/4 piece
of the line (𝛤=0) [4].
[4] D. M. Pozar, “The Quarter-Wave TbansformerMicrowave Engineering,” in Microwave Engineering, NJ, Wiley, 2005, pp. 73-74.

11. ➢ The input impedance Zin are calculated: 𝑍𝑖𝑛 = 𝑍1
𝑅 𝐿+𝑗𝑍1 tan 𝛽𝑙
𝑍1+𝑗𝑅 𝐿 tan 𝛽𝑙
The Quarter-Wave Transformer
➢ 𝛽𝑙 =
2𝜋
𝜆
λ
4
is accepted in this form to take limit 𝛽𝑙 →
𝜋
2
to obtain 𝑍𝑖𝑛 =
𝑍1
2
𝑅 𝐿
➢ For Γ=0 case, Zin should be equal to Z0, so the characteristic impedance turns to 𝑍1 = 𝑍0 𝑅 𝐿
➢ In this project work, The Quarter-Wave Transformer technique has been applied to solve
mismatched impedance problem. The designed transmitter (microstrip line) part has 50Ω impedance.
After the quarter-wave transformer implementation, the power is delivered to the load (antenna)
without power reflection [16].
➢ As it is seen, impedance matching is a crucial point for whom studies on RF/Microwave circuits.
[4] D. M. Pozar, “The Quarter-Wave TbansformerMicrowave Engineering,” in Microwave Engineering, NJ, Wiley, 2005, pp. 73-74.

12. The Quarter-Wave Transformer Implementation
➢ The one of the most essential thing of an antenna is that transmitting power from transmitter to receiver with
zero loss or minimum power loss.
➢ The way in order to achieve this, the source and the load impedance have to be matched.
➢ The case what it is being worked in this project, the impedance matching has to be done between the microstrip
line and the patch.
➢ Transmission line between feeding line and
rectangular patch should have equal
characteristic impedance.
➢ In this case it is 50 Ω. The size of quarter
wave transformer has been calculated by
previously described equations. After that
usual formulas what it is used to calculate
width and length of microstrip line has been
implemented and the last view of the antenna
became as it is seen on figure right.
• The Single Rectangular Patch Antenna.

13. Single Rectangular Patch Antenna
➢ The single patch antenna design has started from a microstrip line design.
➢ A patch design and impedance matching with quarter wave transformer techniques have followed.
➢ All parameters were calculated by following equations in which represented in theory part.
➢ After this, designed geometry were built based on this value at first.
➢ Lastly, the desired conditions have been reached.
Wpatch Lpatch Wqwt Lqwt Wfeed
13.30(mm) 7.40(mm) 0.71(mm) 4.54(mm) 1.69(mm)
• Rectangular patch antenna dimensions.

14. ➢ Designed rectangular patch antenna resonates at 10 GHz with 25dB efficiency.
Single Rectangular Patch Antenna

15. ➢ Both electric and magnetic field distributions belong to design and radiation pattern can be observed
along the next figures.
Single Rectangular Patch Antenna
• H-Field distribution of the Single Rectangular Patch Antenna.
• E-Field distribution of the Single Rectangular Patch Antenna.