1. What is an End Fed Half Wave Antenna Length Calculator?

Definition: This calculator estimates the physical length of an end-fed half-wave antenna based on the desired frequency and velocity factor.

Purpose: It helps radio enthusiasts and engineers design efficient antennas for specific frequency ranges.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Length \) — Physical antenna length (meters)
• \( c \) — Speed of light (299,792,458 m/s)
• \( f \) — Operating frequency (Hz)
• \( Velocity\ Factor \) — Typically 0.95 for wire antennas

Explanation: The formula calculates the half-wavelength at the specified frequency, then applies a velocity factor to account for real-world propagation characteristics.

3. Importance of Accurate Antenna Length

Details: Proper antenna length ensures optimal resonance at the desired frequency, maximizing radiation efficiency and signal strength.

4. Using the Calculator

Tips: Enter the desired frequency in Hz and velocity factor (default 0.95). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a velocity factor?
A: It accounts for the fact that electromagnetic waves travel slower in conductors than in free space, typically 0.95-0.98 for wire antennas.

Q2: Why half-wave length?
A: Half-wave antennas are efficient radiators and provide good impedance matching when end-fed.

Q3: When would I change the velocity factor?
A: Different materials have different velocity factors (e.g., 0.82 for coaxial cable, 0.7 for ladder line).

Q4: Does this work for all frequency bands?
A: Yes, the calculation is valid for any frequency from HF to VHF.

Q5: Should I add extra length for connections?
A: The calculated length is the radiating element length. Add a small amount (5-10cm) for feedpoint connections.