microstrip-line-design-2.4GHz

Design and simulation of a 50Ω microstrip transmission line on FR-4 substrate at 2.4 GHz using analytical calculations, QUCS, and Ansys HFSS

Project Overview

This project demonstrates the complete design, analysis, and simulation workflow for a 50Ω microstrip transmission line on FR-4 substrate operating at 2.4 GHz. The project validates theoretical calculations against both circuit-level simulation (QUCS) and full-wave electromagnetic simulation (Ansys HFSS).

📊 Key Results

• Target Frequency: 2.4 GHz
• Characteristic Impedance: 50Ω
• Simulated Return Loss (S₁₁): -45.44 dB
• Substrate: FR-4 (εᵣ = 4.4, height = 1.6 mm)
• Line Dimensions: Width = 3.059 mm, Length = 34.225 mm

🛠 Skills Demonstrated

• Theoretical Analysis: Microstrip line design using Pozar/Balanis equations
• Circuit Simulation: QUCS for initial validation
• 3D EM Simulation: Ansys HFSS for full-wave analysis
• Impedance Matching: λ/2 transmission line theory
• Technical Documentation: Professional report writing in LaTeX

📁 Repository Structure

🔬 Methodology

1. Analytical Design

• Applied microstrip design equations from Pozar to calculate width and length
• Determined effective dielectric constant (εₑ = 3.33)
• Calculated conductor and dielectric losses
• Designed for 180° phase shift (λ/2) at 2.4 GHz

2. Circuit Simulation (QUCS)

• Verified analytical calculations using transmission line calculator
• Performed frequency sweep from 1-4 GHz
• Achieved excellent initial matching (S₁₁ < -70 dB)

3. Full-Wave Simulation (Ansys HFSS)

• Built 3D model with proper material assignments
• Configured lumped ports with 50Ω renormalization
• Applied radiation boundary conditions
• Validated model and performed fast frequency sweep

📈 Results Comparison

Method	S₁₁ at 2.4 GHz	Key Characteristics
Analytical	Theoretical match	Based on design equations
QUCS	< -70 dB	Ideal circuit simulation
HFSS	-45.44 dB	Realistic 3D EM simulation

🎯 Key Findings

• The designed microstrip line shows excellent impedance matching at the target frequency
• Close agreement between analytical, QUCS, and HFSS results validates the design methodology
• Full-wave simulation provides more realistic results by accounting for 3D effects and radiation
• The project demonstrates a complete RF design workflow from theory to simulation

🚀 How to Reproduce

Prerequisites

• Ansys HFSS (Student/Commercial version)
• QUCS (Quite Universal Circuit Simulator)
• LaTeX distribution (for report compilation)

Simulation Steps

1. Analytical Calculations: Use provided equations to verify dimensions
2. QUCS Simulation: Import transmission line parameters and run analysis
3. HFSS Setup:
   • Create substrate, ground plane, and trace with specified dimensions
   • Assign materials (Copper, FR-4_epoxy)
   • Set up lumped ports and radiation boundary
   • Run frequency sweep and analyze results

📚 Theoretical Background

This project applies concepts from:

• Balanis, Antenna Theory: Radiation mechanisms, impedance matching
• Pozar, Microwave Engineering: Transmission line theory, microstrip design equations
• Practical RF design principles for printed circuit boards

🔗 Related Projects

This is the first in a series of RF/microwave projects:

1. Microstrip Line (Current) - Basic transmission line design
2. Rectangular Waveguide - Waveguide mode analysis
3. Patch Antenna - Radiating element design
4. Impedance Matching Network - Single-stub tuner design

📄 License

This project is open source and available under the MIT License.

👨‍💻 Author

Bernardo Garibello Suan
RF/Microwave Engineering and Antennas Student
Portfolio Project - October 2025