A.
Design Procedure
1. Known Parameters
Dielectric constant (εr) 4.3
Resonant frequency (fr) 5 Ghz
Substrate height (h) 1.6 mm
Speed of light (c) 3 x 10⁸ m/s (constant)
2. Determination of Patch Parameters
➢ Width (W)
Formula:
𝑐 2
W= √
2𝑓𝑟 𝜖𝑟 + 1
𝑐 = speed of light in free space (3 × 108 𝑚𝑠 −1 )
𝑓𝑟 = resonant frequency
𝜖𝑟 = dielectric constant
Calculation and Answer:
𝑐
W=
(𝜖𝑟 + 1)
2𝑓𝑜 √
2
3 × 108
W=
9 (4.3 + 1)
2(5 × 10 )√
2
W = 0.01843𝑚
W = 18.43𝑚𝑚 1
➢ Effective dielectric constant (εreff):
Formula:
1
−
εr+1 εr+1 ℎ 2
εreff = + (1 + 12 )
2 2 𝑊
Calculation and Answer:
4.3+1 4.3+1 (1.6 × 10−3 ) −1
εreff = + (1 + 12 ) 2
2 2 (18.43 × 10−3 )
εreff = 3.805
➢ Extension length (∆L):
Formula:
𝑊
(εreff + 0.3)(
+ 0.264)
∆L = 0.412ℎ ℎ
𝑊
(εreff - 0.258)( − 0.8)
ℎ
Calculation and Answer:
18.43 × 10−3
(3.805 + 0.3)( + 0.264)
∆L = 0.412 × (1.6 × 10−3 ) 1.6 × 10−3
18.43 × 10−3
(3.805 - 0.258)( − 0.8)
1.6 × 10−3
∆L = 0.84𝑚𝑚
➢ Effective length (Leff):
Formula:
𝑐
Leff =
2𝑓𝜊 √εreff
Calculation and Answer:
3 × 108
Leff =
2(5 × 108 ) √3.805
Leff = 0.01538𝑚
Leff = 15.38𝑚𝑚
2
➢ Actual length of patch (L):
Formula:
L = Leff − 2∆L
Calculation and Answer:
L = 15.38 − 2 × (0.84)
L = 13.7mm
3. Determination of Feed-Line Parameters
➢ The width of Microstrip feed line (Wf):
Formula:
7.48 × ℎ
Wf = − 1.25 × 𝑡
εr+1.41
(𝑍𝑜√ )
𝑒 87
Calculation and Answer:
7.48 × (1.6 × 10−3 )
Wf = − 1.25 × 0.035 × 10−3
√4.3+1.41
𝑒 (50 87 )
Wf = 2.99𝑚𝑚
➢ The lengh of Microstrip feed line (Lf):
Formula:
𝑐
𝜆𝑠 𝜆/√εreff (𝑓 )/√εreff
Lf = = =
4 4 4
Calculation and Answer:
3 × 108
( 9 )/√3.805
Lf = 5 × 10
4
Lf = 7.69𝑚𝑚
3
4. Ground Plane Parameters
➢ Width of the ground plane (Wg):
Formula:
Wg = 2 ∗ W
Calculation and answer
Wg = 2 × 18.43mm
Wg = 32.86
➢ Length of the ground plane (Lg):
Formula:
Lg = 2 ∗ L
Calculation and answer
Lg = 2 × 13.7mm
Lg = 27.4mm
4
B. Design Geometry and Dimensions
Figure 1 Dimensional Layout
Antenna Parameter Calculated Value (mm) Optimized Value (mm)
Wg 36.86 36.86
Lg 27.4 26.5
W 18.43 18.3
L 13.7 13.75
Fi 4.16 4.0
Wf 2.99 3.0
hs 1.6 1.6
Gpf 1 1
ht 0.035 0.035
Table 1 Table of proposed antenna parameters (calculated & optimized)
5
C. Simulation results
Figure 2 Antenna final design with port assigned
Figure 3 Return loss (S Parameters)
6
Figure 4 Voltage Standing wave ration (VSWR)
Figure 5 Antenna's gain at assigned frequency
7
D. Summary
In this practical assessment, we designed, simulated, and analyzed a rectangular patch antenna
operating at a resonant frequency of 5GHz. The antenna's dimensions and feedline were
calculated based on known parameters, including a dielectric constant of 4.3, a substrate height
of 1.6 mm, and the speed of light. The final design was optimized to improve its performance,
particularly in terms of S Parameters and Voltage Standing Wave Ratio (VSWR).
Optimization is crucial in antenna design to ensure that the antenna operates efficiently at the
desired frequency and achieves the best performance for its intended application. For this design,
the parameters such as patch length, width, and feedline dimensions were adjusted to ensure
better impedance matching and minimal signal reflection. Specifically, the S Parameters (return
loss) were optimized to be between -20dB and -30dB, indicating minimal reflection, and the VSWR
was optimized to fall between 1.1 and 1.0, which corresponds to near-perfect impedance matching.
Why Optimization is Needed: The initial design calculations provide a starting point, but real-world
factors such as manufacturing tolerances and material imperfections often deviate from theoretical
values. Optimization compensates for these discrepancies, ensuring that the antenna operates
close to its theoretical best performance. For example, fine-tuning the length and width of the patch
ensures better resonance at 5GHz, while adjustments to the feedline improve the transmission of
power from the source to the antenna without losses.
S Parameters Optimization: Achieving an S11 value between -20dB and -30dB ensures minimal
power reflection, with most energy efficiently radiated. Through precise tuning of the patch
dimensions and feedline, impedance mismatch was minimized. The final S11 value of -30.93 dB,
slightly exceeding expectations, indicates exceptional impedance matching. This performance
results from optimizing key factors like patch dimensions, feedline, and dielectric constant, aligning
the antenna design with ideal impedance conditions at 5GHz for minimal reflection and efficient
signal transmission.
The successful optimization of these parameters ensures that the antenna can operate effectively
with minimal signal loss and high efficiency, making it suitable for high-frequency applications such
as wireless communication at 5GHz.
8
E. References
• CST Studio Suite. (2019, August 16). High frequency simulation (Version 2020.0). MIT
Kavli Institute for Astrophysics and Space Research.
https://space.mit.edu/RADIO/Documentation/CST%20Studio%20Suite%20-
%20High%20Frequency%20Simulation.pdf
• Umayah, E. N., & Srivastava, V. M. (2019). Microstrip antenna design for wireless
communication at 2.4 GHz. International Journal of Electrical and Electronic Engineering
& Telecommunications, 8(6), 339–344.
https://www.ijeetc.com/uploadfile/2019/1009/20191009054123619.pdf
• Gocen, C., Akdag, I., Mahouti, T., Belen, M. A., Palandöken, M., & Mahouti, P. (2024).
Knowledge-based methodology of CPW-fed open stub loaded C-shaped microstrip
antenna by surrogate-based modeling. International Journal of Antennas and Propagation.
https://doi.org/10.1155/2024/6247693
• A Review of Reconfigurable Frequency Switching Technique on Microstrip Antenna.
(2018). IOP Conference Series: Journal of Physics: Conference Series, 1019, 012042.
https://doi.org/10.1088/1742-6596/1019/1/012042
