Side Lobe Level Calculator
Calculate broadside first sidelobe level, HPBW, broadside first null angle, directivity, and grating lobe conditions for linear antenna arrays.
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Inputs
Live
Math
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Related
Enter parameters and click Calculate to view results
Formula & Theory
AF(θ) = sin(Nψ/2) / [N·sin(ψ/2)] where ψ = 2π(d/λ)sin(θ) | HPBW ≈ 50.8° / ((N-1)·d/λ) | D_0 ≈ NThis formula is used to calculate antenna parameters for side lobe level calculator.
Overview
Side Lobe Level helps you calculate design values for a antenna arrays project from Number of Elements (N), Element Spacing (d/λ), Amplitude Distribution / Taper Profile. Calculate broadside first sidelobe level, HPBW, broadside first null angle, directivity, and grating lobe conditions for linear antenna arrays. Use the result to make an informed first design decision before choosing hardware, setting dimensions, or evaluating the RF system in its final environment.
Input Guide
Enter Number of Elements (N), Element Spacing (d/λ), Amplitude Distribution / Taper Profile exactly in the units shown by this side lobe level. Check the operating band, unit prefix, and decimal position before calculating; these are the inputs used by the formula.
- Number of Elements (N).
- Element Spacing (d/λ) — use λ.
- Amplitude Distribution / Taper Profile.
Output Guide
The results describe the calculated side lobe level values for the inputs you entered. Check each value against the available space, selected components, feed system, and operating conditions before making a final design decision.
How This Calculator Works
The Side Lobe Level uses AF(θ) = sin(Nψ/2) / [N·sin(ψ/2)] where ψ = 2π(d/λ)sin(θ) | HPBW ≈ 50.8° / ((N-1)·d/λ) | D_0 ≈ N. Supply Number of Elements (N), Element Spacing (d/λ) (λ), Amplitude Distribution / Taper Profile in the displayed units, then use the calculated values as the first engineering target for this antenna arrays design or analysis.
Design Notes
This antenna arrays calculation is based on AF(θ) = sin(Nψ/2) / [N·sin(ψ/2)] where ψ = 2π(d/λ)sin(θ) | HPBW ≈ 50.8° / ((N-1)·d/λ) | D_0 ≈ N. Real-world accuracy depends on factors such as material properties, losses, mounting, nearby conductors, ground interaction, feed-line effects, and construction tolerance. Confirm the final system with measurement or simulation.
Build and Tuning Notes
Apply the side lobe level result as an initial target, then validate it in the intended installation. Keep the physical layout and feed arrangement consistent while testing, change one parameter at a time, and record the measured outcome before making another adjustment.
Frequently Asked Questions
What does the Side Lobe Level calculate?
Calculate broadside first sidelobe level, HPBW, broadside first null angle, directivity, and grating lobe conditions for linear antenna arrays. The calculation provides an initial design value based on Number of Elements (N), Element Spacing (d/λ) (λ), Amplitude Distribution / Taper Profile.
Which inputs are needed for the Side Lobe Level?
Enter Number of Elements (N), Element Spacing (d/λ) (λ), Amplitude Distribution / Taper Profile using the displayed units. Each value directly affects the calculated result, so confirm the unit and operating conditions before running the calculation.
How accurate is this side lobe level?
It follows AF(θ) = sin(Nψ/2) / [N·sin(ψ/2)] where ψ = 2π(d/λ)sin(θ) | HPBW ≈ 50.8° / ((N-1)·d/λ) | D_0 ≈ N. It is accurate for the formula assumptions, but installed performance can change because of materials, loss, environment, mounting, nearby objects, and measurement uncertainty.
What should I do after using the Side Lobe Level?
Compare the result with the practical constraints of your antenna arrays system, then validate the completed design with appropriate measurement equipment or simulation.
Alex Warren
B.Sc. in Electrical & Electronic Engineering (EEE)
Alex specialises in antenna design and wave propagation. His expertise helps ensure these calculators present practical RF concepts, useful design estimates, and clear engineering guidance for students, HAM operators, and wireless professionals.