高周波エンジニアのためのAI・機械学習入門（GPU編35） MATLAB OnlineのAntenna Toolboxのパッチアンテナのアンテナ利得（ゲイン）計算機能を使ってモンテカルロシミュレーションをして、サロゲートモデルのためのデータを作る。

前回は周波数と比誘電率を与えて基板厚み、パッチサイズ(W,L)、フィード位置を推定してみた。

今回はMATLABのAntenna Toolboxのゲインを計算する機能を使って、周波数、比誘電率、基板厚み、パッチサイズ(W,L)、フィード位置を与えるとアンテナ利得（ゲイン）が出てくるサロゲートモデルを作ってみよう。
今回は学習データをモンテカルロシミュレーションで作る。

コードはこちら。これもMATLAB Copilotに聞きながら作った。

monteCarloPatchMicrostrip([6, 12],[2.2 4.4], 3000,'patch_mc_gain3000.csv')

function monteCarloPatchMicrostrip(freqRangeGHz, epsrRange, N, csvFilename)

% monteCarloPatchMicrostrip Generate Monte Carlo dataset of patchMicrostrip designs

%   monteCarloPatchMicrostrip(freqRangeGHz, epsrRange, N, csvFilename)

%

% Inputs:

%   freqRangeGHz  - [f_min f_max] in GHz (e.g. [2.4 2.5])

%   epsrRange     - [epsr_min epsr_max] (relative permittivity)

%   N             - number of Monte Carlo samples (positive integer)

%   csvFilename   - output CSV filename (string)

%

% Output:

%   Writes a CSV file with columns:

%     f_GHz, epsr, h_mm, W_mm, L_mm, feedX_mm, feedY_mm, gain

%

% Notes:

%   - Requires Antenna Toolbox (patchMicrostrip and design).

%   - Frequency is converted to appropriate units internally.

%   - The design uses the 'patchMicrostrip' element and the builtin 'design'

%     function to obtain h, W and L for the given resonant frequency.

%

% Example:

%   monteCarloPatchMicrostrip([2.4 2.5],[2.2 2.3],100,'patch_mc.csv')

arguments

    freqRangeGHz (1,2) double {mustBeFinite, mustBeNonnegative}

    epsrRange (1,2) double {mustBeFinite, mustBePositive}

    N (1,1) double {mustBeInteger, mustBePositive}

    csvFilename (1,:) char

end

% Preallocate results

results = nan(N,8); % f_GHz, epsr, h_mm, W_mm, L_mm, feedX_mm, feedY_mm, Gain

az = 0:5:355;

el = -90:5:90;

rng('shuffle');

for k = 1:N

    % Random sampling (uniform)

    fGHz = rand*(freqRangeGHz(2)-freqRangeGHz(1)) + freqRangeGHz(1);

    epsr = rand*(epsrRange(2)-epsrRange(1)) + epsrRange(1);

    % Convert units

    fHz = fGHz*1e9;

    % Create dielectric substrate

    substrate = dielectric('Name','mcSubstrate','EpsilonR',epsr);

    % Create patchMicrostrip with placeholder W,L; feedOffset set later

    pm = patchMicrostrip('Substrate',substrate);

    % Use design to compute patch geometry for the desired resonant frequency

    % design returns tuned element; use copy to extract h,W,L

    pmDesigned = design(pm, fHz);

    GdBi = pattern(pmDesigned, fHz, az, el);

    [maxdBi, idx] = max(GdBi(:));

    % Extract dimensions (meters)

    W_m = pmDesigned.Width;

    L_m = pmDesigned.Length;

    h_m = pmDesigned.Height;

    feedX_m = pmDesigned.FeedOffset(1);

    feedY_m = pmDesigned.FeedOffset(2);

    % Patch center is at x=0, y=0 in patchMicrostrip.

    % Convert to mm for output.

    W_mm = W_m*1e3;

    L_mm = L_m*1e3;

    h_mm = h_m*1e3;

    feedX_mm = feedX_m*1e3;

    feedY_mm = feedY_m*1e3;

    results(k,:) = [fGHz, epsr, h_mm, W_mm, L_mm, feedX_mm, feedY_mm, maxdBi];

end

% Write CSV with header

header = {'f_GHz','epsr','h_mm','W_mm','L_mm','feedX_mm','feedY_mm','Gain_dBi'};

T = array2table(results,'VariableNames',header);

writetable(T, csvFilename);

end

前回よりは計算時間がかかるのでデータ数は3000個にしてみた。こんな感じでデータができる。

次回はこれをDNNを使って推定しよう。