Microstrip Impedance Calculator — RF PCB Design | RFCalcLab
Professional RF PCB design tool. Calculate characteristic impedance (Z0) and effective dielectric constant for microstrip lines. Supports analysis and synthesis for high-speed digital and RF trace design.
How to Use the Microstrip Calculator
For Analysis, enter trace width (W), substrate height (h), and dielectric constant (εr) to find the characteristic impedance (Z0). Use Synthesis to find the required width for a specific Z0.
Selecting a material preset like FR-4 or Alumina will fill in common dielectric constant values. The effective dielectric constant (εeff) accounts for the fields traveling in both the substrate and air.
This calculator uses the Hammerstad-Jensen formulas, which are highly accurate for typical PCB geometries where W/h ratios are between 0.1 and 10.
Related Topics
- microstrip calculator
- PCB impedance
- characteristic impedance
- microstrip line
- RF PCB
- transmission line
Frequently Asked Questions
- What is a Microstrip line?
- A microstrip is a type of electrical transmission line which can be fabricated with printed circuit board (PCB) technology. It consists of a conducting strip separated from a ground plane by a dielectric layer.
- Why is 50 ohms standard for RF?
- 50 ohms is a compromise between power-handling capability (maximized at 30 ohms) and low loss (minimized at 77 ohms) for air-filled coaxial cables, and it has become the universal standard for RF test equipment.
- How does dielectric constant affect trace width?
- A higher dielectric constant (εr) results in a narrower trace for the same target impedance. This allows for more compact designs but may increase conductor losses due to smaller trace surface area.