dish_dipole_fmincon_demo.m File Reference

Performs sidelobe reduction on a dish antenna using constrained optimization via fmincon. More...

Detailed Description

Performs sidelobe reduction on a dish antenna using constrained optimization via fmincon.

This script sets up a parabolic dish illuminated by a circular aperture, computes its far-field pattern, and then optimizes the currents of dipoles placed in a ring around the feed to suppress sidelobes. A nonlinear least-squares cost function is minimized using fmincon, subject to anti-symmetry constraints on the dipole currents to preserve main lobe symmetry.

KeyFeatures

• Builds a parabolic reflector surface and computes induced surface currents using physical optics.
• Computes the far-field pattern in a fixed φ-plane.
• Constructs a system matrix (Zmn) that relates dipole excitations to far-field contribution.
• Uses fmincon to solve a constrained least-squares problem for dipole weights.
• Enforces anti-symmetry across the dipole ring to maintain main lobe direction.
• Plots the radiation pattern before and after dipole superposition.

Parameters

• Frequency: 2.5 GHz
• Dish focal length: 20 × λ₀
• Dipole ring radius: 1.1 × (dish aperture radius)
• Number of dipoles: 50
• Optimization method: fmincon with anti-symmetry linear constraints

Note

The objective is to reduce sidelobes outside the main beam while preserving beam shape.

Mutual coupling effects are not modeled.

See also

ParabolicDish

SimpleDipole

circ_aperture_fields

fmincon