How do I create a mesh of a sinuous antenna geometry in order to simulate its radiation patterns?

I am a complete beginner to MATLAB, and have searched up commands like customAntennaMesh to model a sinuous antenna’s radiation patterns. I have the equations to plot the curves required for the sinuous geometry. However, I don’t understand what is meant by the (points, triangles) input required by the command.

What should I do to create the geometry, or is there any other command I should try?

Answer 1

[AR]

Hi @Gillian Daz,

The function “customAntennaMesh” is part of the Antenna Toolbox in MATLAB and is used to define custom antenna geometries using a mesh representation. It's ideal for designing complex antenna shapes that are not available in the toolbox's predefined options.

It needs 2 inputs:

1. Points: It is a “2 × N” or “3 × N” matrix representing Cartesian coordinates in meters, where “N” is the number of points.

• 2 × N matrix - Defines points in 2D (x, y).
• 3 × N matrix - Defines points in 3D (x, y, z), but “z” must be constant or zero.

2. Triangles: It is a “4 × M” matrix, where “M” is the number of triangles. The first three rows define triangle vertices (indices of points), and the fourth row assigns a domain number.

Refer the below link for “customAntennaMesh” function:

https://www.mathworks.com/help/antenna/ref/customantennamesh.html

Here is an example code for sinuous antenna mesh:

clc; clear; close all; 

% Define parameters for sinuous curve 
a = 0.1;   % Scaling factor (assumed) 
b = 0.2;   % Growth rate (assumed) 
t = linspace(0, 4*pi, 50); % Angle range for the sinuous shape 

% Compute Cartesian coordinates (r(t) = a * exp(b * t)) 
x = (a * exp(b * t)) .* cos(t); 
y = (a * exp(b * t)) .* sin(t); 
z = zeros(size(x)); % Keep z = 0 for a 2D structure 

% Create the points matrix (3 x N) 
points = [x; y; z]; 

A sinuous antenna has a spiral-like shape, which makes it difficult to manually define the triangular mesh. The function “delaunayTriangulation(x, y)” automatically computes a triangular mesh connecting the given 2D points.

The output is a connectivity list, which provides the indices of three points forming each triangle. “dt.ConnectivityList” provides triangle indices based on the computed points.

Refer the below link for “delaunayTriangulation” function:

https://www.mathworks.com/help/matlab/ref/delaunaytriangulation.html

% Use Delaunay triangulation for correct connectivity 
dt = delaunayTriangulation(x', y'); 
triangles = [dt.ConnectivityList'; ones(1, size(dt.ConnectivityList, 1))]; 

% Create and visualize the custom antenna mesh 
mesh = customAntennaMesh(points, triangles); 
figure; 
show(mesh);  % Display mesh without additional arguments 
title('Sinuous Antenna Mesh'); 

A possible workaround is to use “patch()” function for visualization while keeping “delaunayTriangulation()” to generate the mesh.

Refer the below link for “patch()” function:

https://www.mathworks.com/help/matlab/ref/patch.html

I hope this helps!