Monopole Antenna Design and Simulation using CST

Introduction

• Focus of this tutorial: Design and simulation of monopole antennas using CST.
• Experiment number: 2 in the series on antennas and wave propagation.

Key Topics to Discuss

1. Introduction to Monopole Antennas
2. Parameters Calculations for Monopole Antenna
3. CST Design Procedure for Monopole Antenna
4. Results of Monopole Antenna
5. Hardware Design of Monopole Antenna

Monopole Antenna Overview

• Definition: A monopole antenna consists of a straight rod-shaped conductor (monopole) mounted perpendicularly over a conductive surface (ground plane).
• Comparison: Monopole antennas have one pole; dipole antennas have two poles.
• Application: Can be used for various frequency ranges.

Parameters Calculations

• Wavelength Calculation:

  • Formula: ( \lambda = \frac{c}{f} )
    • ( c = 3 \times 10^8 ) m/s (speed of light)
    • For Wi-Fi at 2.45 GHz: ( f = 2.45 ) GHz
    • ( \lambda = 122.5 ) mm

• Length of Monopole:

  • For a quarter wave monopole: ( L = \frac{\lambda}{4} )
    • Length = 30.625 mm

• Radius Calculation:

  • Radius must be less than or equal to ( \frac{\lambda}{20} )
  • For 2.45 GHz: Radius < 1.5 mm; choose 1.2 mm or 1 mm.

• Ground Parameters:

  • Simplified Formula: ( G = \frac{\lambda}{2} )
  • Ground length: 61.25 mm.

CST Design Procedure

1. Starting CST:

   • Open CST and create a new template for microwave/RF optical antenna design.
   • Choose Time Domain Solver.
   • Define frequency range: 1 to 3 GHz.

2. Designing Monopole Antenna:

   • Model using a surplus cylinder.
   • Set values: Inner radius = 0, Outer radius = 1.2 mm, and Length = 30.625 mm.
   • Material: Perfect Electric Conductor (PEC).

3. Designing Ground:

   • Create a brick model for ground with dimensions based on calculated ground length.
   • Ground must be below the monopole.

4. Cutting Ground for Discrete Port:

   • Create a circular standard to cut ground for the discrete port.
   • Radius = monopole radius + gap (1.2 mm + 0.5 mm).

5. Defining Discrete Port:

   • Specify location and set impedance to 50 ohms.
   • Apply settings and confirm.

6. Simulation:

   • Start simulation and monitor the results.

Results of Monopole Antenna

• S Parameters:

  • Result: Approximately -9 or -10 dB at 2.45 GHz.

• Gain:

  • Gain: ~1.17 dB; omnidirectional nature confirmed.

• Radiation Patterns:

  • E-field and H-field patterns can be analyzed.
  • Surface current can be animated for better understanding.

Hardware Design of Monopole Antenna

• Modern monopole antennas often incorporate cylindrical shapes for the ground.
• Components:
  • Monopole rod
  • Hollow cylindrical ground
  • Connector for powering up the antenna
  • Loader for improving radiation resistance, efficiency, and bandwidth.

Conclusion

• Overview of designing and simulating monopole antennas using CST completed.
• Reminder to like, subscribe, and press the bell icon for updates.