Antenna Length Calculator
Calculate the approximate physical length of half-wave dipole and quarter-wave vertical antennas for a given frequency.
Antenna Parameters
Antenna Length Formulas
The length of resonant antennas is directly related to the wavelength of the signal they are designed for. The formulas below account for the velocity factor (VF) of the antenna material, which is typically around 0.95 for bare wire.
Where:
- λ = Wavelength in meters (m)
- Frequency = Frequency in Megahertz (MHz)
- VF = Velocity Factor (dimensionless, typically 0.95 for wire)
Common Antenna Types and Uses
| Antenna Type | Description & Common Use |
|---|---|
| Dipole Antenna | Simple, widely used for HF, VHF, and UHF. Omnidirectional or figure-8 pattern. |
| Vertical Antenna | Omnidirectional, often used for mobile and marine radio. Requires a ground plane. |
| Yagi-Uda Antenna | Directional, high gain. Used for TV reception, amateur radio, and point-to-point communication. |
| Loop Antenna | Compact, can be directional or omnidirectional. Used for AM radio, RFID, and direction finding. |
| Patch Antenna | Low profile, directional. Used in GPS devices, Wi-Fi, and satellite communication. |
Frequently Asked Questions
What is an antenna?
An antenna is a transducer designed to transmit or receive radio waves. It converts electric power into radio waves, and vice versa.
What is wavelength?
Wavelength is the spatial period of a periodic wave – the distance over which the wave's shape repeats. In radio, it's inversely proportional to frequency.
What is velocity factor?
The velocity factor (VF) is the speed at which an electromagnetic wave propagates through a transmission line or antenna element, relative to the speed of light in a vacuum. It is a dimensionless number between 0 and 1. For bare wire antennas, a typical velocity factor of 0.95 is often used.