What Is the Antenna Dipole & Monopole Resonant Length Calculator?
Antenna resonant length sizing ensures zero reactive impedance at the design carrier frequency.
How Does the Antenna Dipole & Monopole Resonant Length Calculator Work?
Standing wave current and voltage distributions form along the antenna; at resonance, radiation resistance matches feedline impedance.
Antenna Dipole & Monopole Resonant Length Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
L_{dipole} = \frac{c}{2 f} \cdot k_v \approx \frac{143}{f_{\text{MHz}}} \text{ (m)}, \quad L_{mono} = \frac{c}{4 f} \cdot k_v \approx \frac{71.5}{f_{\text{MHz}}} \text{ (m)}
Antenna length is wavelength fraction multiplied by speed of light over frequency and end-effect velocity factor.
How to Use the Antenna Dipole & Monopole Resonant Length Calculator
- Enter operating frequency in MegaHertz.
- Select dipole, monopole, or full-wave loop geometry.
- Optionally adjust velocity factor.
Step-by-Step Example Calculation
2-Meter Amateur Radio Dipole (146.0 MHz)
Input Values:
frequencyMhz:146.0
antennaType:half-wave-dipole
velocityFactor:0.95
Worked Steps: Free-space wavelength is 2.053 m. Resonant half-wave dipole length is 0.975 m (38.4 inches), requiring two 0.488 m (19.2 in) wire elements.
Understanding Your Result
Total Length (m/ft): Overall resonant physical length.
Element Leg Length: Length of each conductor arm for center-fed dipoles.
Radiation Resistance: Natural driving point impedance.
Factors That Affect the Result
- Frequency inversely scales length; wire thickness slightly reduces velocity factor.
When Should You Use This Calculator?
- Ham radio antenna building, wireless telemetry transceiver setup, and RF field engineering.
Assumptions & Limitations
- Assumes antenna installed at least 0.5λ above ground plane to minimize ground detuning.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Classical antenna theory formulation using speed of light c = 2.998×10⁸ m/s.