How to Use This Calculator
- Enter the original trace length (L) of your microstrip line
- Set the desired bend angle (θ). A common value is 45°, but other angles can be used depending on your design
- Input the trace width (W) of your microstrip line
- Specify the substrate height (H) and dielectric constant (εr) of your PCB material
- Click the "Calculate" button to determine the required outer radius (R), inner radius (r), and bend length (S)
Design Considerations
The microstrip mitred bend is commonly used in RF and microwave circuits to change the direction of transmission lines while minimizing signal distortion. The key parameters to consider are:
- Outer Radius (R): The larger radius of the bend, which determines the overall bend shape
- Inner Radius (r): The smaller radius of the bend, which should be greater than the trace width to avoid signal interference
- Bend Length (S): The horizontal distance along the original trace path from the start to the end of the bend
Principle of Operation
The mitred bend is essentially a series of connected quarter-circles that approximate a 90° bend. The calculation assumes a simple geometric model where the outer and inner radii are determined by the original trace length, bend angle, and trace width. For more complex designs, additional considerations such as dielectric loss and impedance matching may be necessary.
Practical Tips
- For a 45° bend, the outer radius is typically equal to the original trace length
- The inner radius should be at least equal to the trace width to avoid coupling between the trace and the bend
- For sharper bends (smaller angles), the outer radius will need to be larger
- Always verify your design with electromagnetic simulation software for high-frequency applications