Free Yagi Calculator — Optimize Elements, Gain, and Spacing

Step-by-Step Yagi Calculator for Amateur Radio and TV Antennas

What it is

A step-by-step Yagi calculator is a guided tool that helps you design Yagi–Uda antennas by computing element lengths, spacings, and performance estimates from a target frequency and a few design choices. It’s aimed at amateur radio operators and TV antenna builders who want practical, buildable dimensions and basic performance metrics without deep EM simulation.

Inputs typically required

• Target frequency (MHz)
• Number of elements (driven + reflectors + directors)
• Boom length or desired maximum spacing (optional)
• Element diameter or material (affects end-loading correction)
• Design priority (gain, front-to-back ratio, or compact size)
• Feed type (folded dipole, driven dipole, matching method)

Step-by-step workflow

1. Enter frequency — calculator converts to wavelength (λ = c / f) and sets scale.
2. Choose element count and layout — select total elements and whether to include one reflector and multiple directors.
3. Select element diameter/material — applies thickness correction to element lengths.
4. Set initial spacings — uses typical ratios (reflector ~0.15–0.25 λ behind driven element; directors ~0.1–0.2 λ forward).
5. Compute element lengths — driven element ~0.475–0.5 λ adjusted by diameter; reflector slightly longer; directors progressively shorter.
6. Iterate for performance — calculator provides estimated gain, front-to-back ratio, and impedance; allow tuning by adjusting spacings or element count.
7. Output build dimensions — element lengths, positions on boom, suggested feed/matching, and construction notes.
8. Generate a summary — printable parts list and quick assembly guide.

Typical outputs and estimates

• Element lengths and boresight positions (mm or inches)
• Estimated gain (dBi) and front-to-back ratio (dB) — approximate, depends on assumptions
• Feedpoint impedance — helps choose matching network (e.g., gamma match, folded dipole)
• Beamwidth — approximate half-power beamwidth (degrees)
• Construction tips — mounting, insulation, and mechanical tolerances

Practical tips and caveats

• Use iteration: small spacing changes can noticeably affect F/B and impedance.
• Account for support structure: boom and mounting hardware can detune elements slightly.
• Element thickness matters: thicker elements shorten required length.
• Simulations are more accurate: NEC-based tools (e.g., 4nec2) give better results for final tuning.
• Safety: when designing for transmit use, ensure adequate power handling and grounding.

Who benefits

• Amateur radio operators building VHF/UHF yagis for ham bands.
• DIY TV antenna builders optimizing reception for a particular channel.
• Educators and students learning practical antenna design without deep theory.

If you want, I can generate a concrete set of element lengths and spacings for a specific frequency and element count — tell me the frequency (MHz) and number of elements.