1. What is Parallel Wire Impedance?

The parallel wire impedance is the characteristic impedance of a transmission line consisting of two parallel conductors. It's important in RF and microwave engineering for designing balanced transmission lines.

2. How Does the Calculator Work?

The calculator uses the parallel wire impedance equation:

Where:

• \( Z \) — Characteristic impedance in ohms (Ω)
• \( \epsilon_r \) — Relative permittivity of the medium (unitless)
• \( s \) — Center-to-center separation of the wires (meters)
• \( d \) — Diameter of the wires (meters)

Explanation: The equation accounts for the geometry of the wires and the dielectric properties of the surrounding medium.

3. Importance of Impedance Calculation

Details: Accurate impedance calculation is crucial for impedance matching in transmission lines to minimize signal reflections and maximize power transfer.

4. Using the Calculator

Tips: Enter relative permittivity (≥1), wire separation (must be greater than wire diameter), and wire diameter. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is typical impedance for parallel wires?
A: Common values range from 100Ω to 600Ω depending on geometry and dielectric. 300Ω was common for TV antenna leads.

Q2: How does wire spacing affect impedance?
A: Impedance increases with larger spacing between wires (logarithmic relationship).

Q3: What materials affect relative permittivity?
A: Air has εr≈1, common dielectrics like polyethylene have εr≈2.3, PTFE about 2.1.

Q4: When is this calculation most accurate?
A: When wire separation is much larger than diameter and uniform dielectric surrounds both wires.

Q5: How does frequency affect this calculation?
A: This is a DC/low-frequency approximation. At high frequencies, skin effect and other factors come into play.