Yagi-Uda Antenna Calculator — Directors & Pattern

Yagi-Uda Antenna Calculator (Directors & Pattern)

Quick design + visualization for a driven element + reflector + N directors. Includes SVG schematic and approximate radiation pattern (array-factor estimate).

Design Inputs

Frequency (MHz)

Number of Directors

Director length factor (relative to driven)

Spacing (λ) between elements

Boom orientation

Driven element length correction factor

Use driven length ≈ drivenFactor × λ. Default 0.47 (accounts for end effects).

Element Dimensions (results)

Approximation note: Pattern produced by an array-factor approximation treating elements as point sources with amplitudes proportional to element length. It gives qualitative beam direction and relative front-to-back behavior but not accurate side-lobes or real gain numbers. Use NEC/EZNEC for precise performance.

Visualization

Schematic (scaled)

Radiation Pattern (approx.)

Quick Actions

How the pattern is computed (brief)

We compute a simple array factor: AF(θ)=Σ aₙ·e^{j·k·xₙ·cosθ} where aₙ is amplitude (∝ element length), xₙ are element boom positions, and k=2π/λ. This shows approximate beam shape and relative lobes.

For detailed design use full EM modeling. This calculator is great for conceptual design, quick comparisons, and educational use.

Antenna Handbook