How to Use This Calculator
- Enter the physical dimensions of your microstrip line:
- Trace Width (W): The width of the conductive trace in millimeters.
- Substrate Thickness (h): The thickness of the dielectric substrate in millimeters.
- Enter the material properties of your substrate:
- Relative Permittivity (εr): The dielectric constant of the substrate material. Common values include FR4 (4.0), Rogers RT/Duroid 5880 (4.4), and Air (1.0).
- Loss Tangent (δ): The dielectric loss of the substrate material. This value is typically very small (0.001-0.02) and can often be left at the default value.
- Click the "Calculate" button to compute the characteristic impedance and propagation constant.
Understanding the Results
The calculator provides two key results:
- Characteristic Impedance (Z₀): This is the impedance that the microstrip line presents to a transmission line. It's critical for ensuring proper signal transmission and minimizing reflections. Typical values for microstrip lines range from 50Ω (for high-frequency applications) to 100Ω (for balanced differential signals).
- Propagation Constant (β): This represents how the signal propagates through the transmission line per unit length.
Design Tips
For optimal performance, it's generally recommended to design microstrip lines with a characteristic impedance of 50Ω or 75Ω, which are standard values used in many RF and communication systems. You can adjust the trace width and substrate thickness to achieve your desired impedance value.
The formula used in this calculator is based on Harrington's approximation, which provides good accuracy for most microstrip applications.