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Antenna Length Calculator
Calculators / Antenna Length
Antenna Length
Calculator
The essential general-purpose antenna length calculator. Calculate the physical length for a dipole, quarter-wave, half-wave, or full-wave antenna at any frequency — with velocity factor and conductor diameter corrections. The pillar calculator for any RF project.
Dipole / Quarter-wave
Half-wave
Full-wave
⚙ Antenna Length Engine
Dipole
L = λ/2
Quarter-Wave
L = λ/4
Half-Wave
L = λ/2
Full-Wave
L = λ
Free-space λ = — m
Bare metal ≈ 0.95–0.98. Insulated wire ≈ 0.66–0.85
Affects length via thick-element correction
Material affects effective velocity factor
Advanced Parameters
End capacitance shortening (0.95–0.98). Dipoles only.
m
Affects feedpoint impedance via image theory
For quarter-wave monopole on ground plane
L = λ/n. 2=half-wave, 4=quarter-wave, 1=full-wave
All Antenna Types — This Frequency
| Type | Fraction | Length | Half-Length | Zin (approx) | Gain |
|---|---|---|---|---|---|
| Enter values above | |||||
Calculated Results
Dipole Length (L)
—m
Half-Length (L/2)—
Free-space λ—
λ in conductor—
Length / λ—
Feedpoint Impedance—
Gain (dBi)—
Bandwidth (approx)—
Thick-element correction—
Length in inches—
Length in feet—
Select antenna type and enter frequency to calculate.
📖 Antenna Length Theory
All resonant antenna lengths are simple fractions of the operating wavelength λ. The wavelength in free space is λ = c/f, but the physical antenna is always slightly shorter due to the velocity factor and end effects.
General Formula
L = (k × c) / (n × f)
k = velocity factor, c = 3×10⁸ m/s, n = divisor (1, 2, 4…), f = frequency in Hz
Practical Shorthand
Dipole: L(m) = 143/f(MHz)
Quarter-wave: L(m) = 71.5/f(MHz)
Full-wave: L(m) = 286/f(MHz)
These classic shortcuts include VF ≈ 0.95 and end-effect ≈ 0.97.
The velocity factor k accounts for the fact that electromagnetic waves travel slightly slower in real conductors than in free space. For bare copper or aluminium tubes, k ≈ 0.95–0.98.
The end-effect further shortens the dipole by ≈3% due to capacitance at the wire tips. This is automatically included in the standard 143/f formula.
📡 Antenna Shape & Pattern Viewer
Live Preview
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◉ Shape & radiation pattern scale with type
View Mode
Frequency
144 MHz
1 MHz1000 MHz
Type
Dipole (λ/2)
λ/4λ
Antenna Shape
E-Plane Pattern
ℹ
Design Insights
Select antenna type and enter frequency to see design insights.
Common Applications
Amateur Radio
HF dipoles, VHF/UHF quarter-wave verticals, and half-wave end-fed antennas for ham radio operation.
IoT & Wireless
PCB trace antennas, whip antennas, and wire antennas for WiFi, Bluetooth, Zigbee, LoRa and ISM bands.
Broadcast & FM
Half-wave dipole arrays and quarter-wave ground-plane antennas for FM/AM/DAB broadcast transmitters.
RF Prototyping
Quick antenna sizing for any RF project — from 1 MHz to 10 GHz — during circuit design and testing phases.
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