How do you calculate Yagi antenna dimensions?

Find the wavelength (299,792,458 ÷ frequency), place the elements with a proven spacing sequence (DL6WU: 0.2 λ reflector to driven element, then 0.075, 0.18, 0.215, 0.25 … up to 0.4 λ), and size each element as a fraction of λ: about 0.49 λ for the reflector, 0.476 λ for a split-dipole driven element and 0.435 λ falling to about 0.38 λ for the directors. Correct the lengths for element diameter and for a metal boom, then tune the driven element for lowest SWR.

What are the Yagi antenna dimensions for 2 meters (144 MHz)?

For a 7-element DL6WU Yagi at 144 MHz with 6 mm elements insulated from the boom: reflector 1,047.6 mm, driven element 990.0 mm at 416.4 mm, and directors 930.6, 925.3, 916.3, 907.8 and 900.3 mm, the last at 2,498.3 mm (a 1.2 λ boom, about 9.8 dBd). Mounting the elements through a bonded 20 mm metal boom adds the boom correction to every parasitic element.

What is Yagi boom correction?

When elements pass through and touch a metal boom, the boom electrically shortens them, so each parasitic element must be cut longer. The DL6WU/Rothammel correction grows with boom diameter relative to wavelength: about a third of the boom diameter for thin booms, rising to about 0.7 × the boom diameter when the boom is 0.05 λ thick. Elements on insulators above the boom, or a non-metal boom, need no correction.

How much gain does a Yagi have?

Gain depends mainly on boom length, not element count. For well-designed DL6WU Yagis it is about 9.15 + 3.39·ln(boom length in λ) dBd: roughly 9.8 dBd on a 1.2 λ boom, 13.1 dBd on 3.2 λ and 17.2 dBd on 10.8 λ (add 2.15 for dBi). Each doubling of boom length adds about 2.3 dB.

How many elements does a Yagi with one reflector, one driven element and 6 directors have?

Eight. A Yagi-Uda element count includes the reflector, the driven element and every director, so 1 + 1 + 6 = 8 elements. Select 8 elements here to get that layout.

What is a Yagi-Uda antenna?

A Yagi-Uda antenna is a directional antenna array consisting of a driven element (dipole), one reflector behind it, and one or more directors in front. The parasitic elements (reflector and directors) focus the radiation into a beam, increasing gain in the forward direction.

How accurate are these calculations?

The DL6WU positions and reference lengths reproduce published designs; a 9-element 2 m check against DL6WU's own program agrees within about 1% on element lengths and gives the same 11.2 dBd gain. Diameter and boom corrections are interpolated from curves, so very thick elements (d/λ above 0.01) or unusual mounting need NEC modelling. Always trim the driven element on the finished antenna.

What material and element diameter should I use?

Aluminum tube or rod is the usual choice. Thinner elements need to be slightly longer, which the DL6WU method handles through the d/λ correction: 4–6 mm suits 2 m and 70 cm, while at 1296 MHz and above even 2–3 mm rod exceeds d/λ 0.01, so model those designs or use published ones.

What is the driven element and how do I feed it?

The driven element is the active dipole connected to your feedline. It is typically a folded dipole with a 4:1 balun or a split dipole with a 1:1 current balun. The calculator gives a split-dipole starting length; cut it in half at the centre feed point and trim both halves equally for lowest SWR.

Can I use this calculator for Wi-Fi Yagis?

Yes. Enter 2400 MHz for 2.4 GHz Wi-Fi or 5800 MHz for 5.8 GHz. Elements are only a few centimetres long, so precision cutting matters, and the element diameter should stay near 1.25 mm or less at 2.4 GHz (d/λ 0.01) for the DL6WU corrections to apply.

Yagi Antenna Calculator

Enter a frequency, element count and element diameter to get DL6WU element lengths and positions, corrected for element thickness and for elements mounted through a metal boom, with an estimated gain; or switch to a simple uniform-spacing layout you can tune by hand.

A Yagi antenna calculator turns a frequency into element lengths and spacing.

Antenna Parameters

Frequency (MHz)

Common: 144 MHz (2m), 432 MHz (70cm), 2400 MHz (Wi-Fi)

Design method

DL6WU: proven wide-band design used by most VHF/UHF builders; lengths corrected for element and boom diameter.

Number of Elements

Reflector + driven element + directors (2 to 32)

Parasitic element diameter (mm)

DL6WU data covers d/λ 0.002–0.01.

Element mounting

Boom diameter (mm)

Band Quick-Select

Set frequency and element count, then click Calculate.

Results include element lengths and boom spacing.

Frequency

Wavelength

Boom Length

Est. Gain

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Element Dimensions

Element	Type	Length (mm)	Length (cm)	Length (in)	Spacing from Previous (mm)	Pos. from Refl. (mm)

Antenna Diagram (top view, not to scale)

Design Notes

Method and engineering limits

DL6WU mode: element positions use the DL6WU spacing sequence (0.200, 0.075, 0.180, 0.215, 0.250, 0.280, 0.300, 0.315, 0.330, 0.345, 0.360, 0.375, 0.390, then 0.400 λ). Reference lengths come from W4RNL's NEC study of the DL6WU design (RSGB VHF/UHF DX Book, 4 mm elements at 432 MHz) and are scaled to your wavelength. The change with element diameter is interpolated on a log scale between Rothammel's DL6WU curves for d/λ = 0.002 and 0.01; the boom correction for elements through a bonded metal boom follows Rothammel's DL6WU curve. Gain ≈ 9.15 + 3.39·ln(boom/λ) dBd.

Simple mode scales a uniform-spacing heuristic and is not a named optimized design. In both modes impedance matching and tuning remain the builder's job, as outlined in NBS Technical Note 688.

References: W4RNL: Appreciating DL6WU long-boom Yagi design, NIST/NBS Technical Note 688 and NIST CODATA c. Use NEC modeling and an antenna analyzer before transmitting. Numeric inputs are calculated locally in your browser.

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Quick answer

A Yagi antenna calculator turns a frequency into element lengths and spacing. With the DL6WU design, the wavelength is 299,792,458 ÷ frequency; element spacing grows from 0.2 λ (reflector to driven element) to 0.4 λ along the boom, directors taper from about 0.435 λ, and lengths are corrected for element diameter and a metal boom.

Examples

144 MHz, 7 el, 6 mm	Length	From reflector
Reflector	1,047.6 mm	0 mm
Driven element	990.0 mm	416.4 mm
Director 1	930.6 mm	572.5 mm
Director 3	916.3 mm	1,394.9 mm
Director 5	900.3 mm	2,498.3 mm

Pick a band, element count and element diameter, then copy the element table as text.

Summary

The default method follows the DL6WU long-boom Yagi: the classic tapered spacing (0.200, 0.075, 0.180, 0.215, 0.250 … 0.400 λ) and director lengths taken from a NEC-checked DL6WU design (RSGB VHF/UHF DX Book data, 4 mm elements at 432 MHz), scaled to your frequency. Lengths are adjusted for element diameter (Rothammel/DL6WU curves for d/λ 0.002–0.01) and, for elements passing through and touching a metal boom, a boom correction is added to every parasitic element. Forward gain is estimated from boom length with G ≈ 9.15 + 3.39·ln(boom/λ) dBd, which matches published DL6WU results within about 0.15 dB from 1.8 λ to 11 λ booms. A simple uniform-spacing mode remains for quick experiments. All results are construction starting points: model the antenna in NEC and tune the driven element with an analyzer.

How it works

Enter the centre frequency in MHz or pick a band (6 m, 2 m, 70 cm, 23 cm, Wi-Fi).
Choose the DL6WU method (default) or simple uniform spacing, and 2 to 32 elements.
For DL6WU, enter the element diameter and how the elements are mounted; a bonded metal boom adds a boom correction.
Element positions follow the DL6WU spacing sequence; director lengths taper with director number and are corrected for d/λ.
The table lists every element length in mm, cm and inches, its spacing and its position from the reflector, with the estimated gain.
Copy the table as text for your build sheet or NEC model.

Use cases

Designing a ham radio Yagi beam antenna for VHF or UHF bands.
Building a high-gain TV receiving antenna for a specific channel frequency.
Planning a point-to-point Wi-Fi link antenna for 2.4 GHz or 5.8 GHz.
Academic study of antenna design and electromagnetic wave propagation.
Verifying dimensions of a commercial Yagi against published specifications.
Cutting elements to length before assembling a homebrew antenna project.
Producing a geometry draft to transfer into NEC antenna-modeling software.
Scaling an existing design to a different operating frequency.

Frequently Asked Questions

Last updated: 2026-10-09 · Reviewed by Nham Vu