% Vivaldi_Sweep.m % % Automated parameter sweep for the CPW-fed Vivaldi antenna, built on top % of the now-debugged, fast-converging core from Vivaldi_OpenEMS_Start.m. % Runs several (taper.L, taper.ya) combinations back-to-back with NO user % interaction needed, and prints a summary table at the end so you can see % at a glance which combination gets closest to S11 < -10 dB from 850 MHz % upward - instead of testing one combination at a time by hand. % % Fixed/confirmed-stable choices carried over from Vivaldi_OpenEMS_Start.m: % - taper.y0 derived from cpw.center_w/cpw.gap (no short at the throat) % - taper.R = 0.023 (0.014/0.018 were numerically unstable) % - N = 10 taper polygon points, pre_tol/merge_tol mesh-line cleanup % (avoids the SmoothMesh hangs seen with denser point sets) % - coarser exploration mesh divisors (/20, /10) % Each run's NrTs cap is deliberately smaller than the production script % (1,000,000) to bound worst-case time per combination; if a combination % is unstable it will hit this cap quickly rather than run for 30+ min. % % NOTHING in this script requires you to press anything or check anything % mid-run. Start it, walk away, come back to the summary table at the end. % % Figures are suppressed during the sweep for speed; only the final S11 % curve for the automatically-selected best combination is plotted at the % end (Figure 1). close all clear clc max_recursion_depth(10000); physical_constants; unit = 1e-3; f_low = 850e6; f_high = 2000e6; f0 = (f_low + f_high)/2; fc = (f_high - f_low)/2 + 0.3e9; substrate.epsR = 4.3; substrate.tand = 0.023; substrate.kappa = substrate.tand * 2*pi*f0 * substrate.epsR * EPS0; substrate.thickness = 1; feed.throat_run = 15; feed.R_ref = 50; cpw.center_w = 3.0; cpw.gap = 0.4; taper.y0 = cpw.center_w/2 + cpw.gap; taper.R = 0.023; % confirmed stable - not swept % ---- combinations to test: [taper.L, taper.ya] in mm ---- combos = [ ... 160 50; ... 200 50; ... 240 50; ... 160 60; ... 200 60; ... 240 60 ... ]; N = 10; NrTsCap = 1000000; results = []; % columns: L, ya, worstS11dB_in_band, minS11dB, minS11freqMHz, converged(1/0) freq = linspace(f_low*0.7, f_high, 601); band_idx = freq >= f_low & freq <= f_high; for k = 1:size(combos,1) taper.L = combos(k,1); taper.ya = combos(k,2); board.length = feed.throat_run + taper.L + 20; % 20 mm margin board.width = 2*(taper.ya + 20); % 20 mm margin each side fprintf('\n=== Combo %d/%d: taper.L=%d mm, taper.ya=%d mm (board %dx%d mm) ===\n', ... k, size(combos,1), taper.L, taper.ya, board.width, board.length); FDTD = InitFDTD('NrTs', NrTsCap); FDTD = SetGaussExcite(FDTD, f0, fc); BC = {'MUR' 'MUR' 'MUR' 'MUR' 'MUR' 'MUR'}; FDTD = SetBoundaryCond(FDTD, BC); x_pts = linspace(0, taper.L, N); RL = taper.R * taper.L; C1 = (taper.ya - taper.y0) / (exp(RL) - 1); C2 = (taper.y0*exp(RL) - taper.ya) / (exp(RL) - 1); y_pts = C1*exp(taper.R*x_pts) + C2; y_taper_abs = feed.throat_run + x_pts; inner_x = y_pts; inner_y = y_taper_abs; outer_x = ones(1,N) * (board.width/2); outer_y = fliplr(y_taper_abs); Ppos = [ [inner_x, outer_x] ; [inner_y, outer_y] ]; Pneg = [ -[inner_x, outer_x] ; [inner_y, outer_y] ]; CSX = InitCSX(); SimBox = [board.width+300, board.length+300, 300]; mesh = struct(); mesh.x = [-SimBox(1)/2 SimBox(1)/2]; mesh.y = [-50 SimBox(2)-50]; mesh.z = [-SimBox(3)/2 SimBox(3)/2]; CSX = AddMaterial(CSX, 'substrate'); CSX = SetMaterialProperty(CSX, 'substrate', 'Epsilon', substrate.epsR, 'Kappa', substrate.kappa); start = [-board.width/2, 0, 0]; stop = [ board.width/2, board.length, substrate.thickness]; CSX = AddBox(CSX, 'substrate', 0, start, stop); CSX = AddMetal(CSX, 'copper'); start = [-cpw.center_w/2, 0, substrate.thickness]; stop = [ cpw.center_w/2, feed.throat_run, substrate.thickness]; CSX = AddBox(CSX, 'copper', 10, start, stop); CSX = AddPolygon(CSX, 'copper', 10, 2, substrate.thickness, Ppos, 'CoordSystem', 0); CSX = AddPolygon(CSX, 'copper', 10, 2, substrate.thickness, Pneg, 'CoordSystem', 0); Pfeed_pos = [ [cpw.center_w/2+cpw.gap, board.width/2, board.width/2, cpw.center_w/2+cpw.gap] ; ... [0, 0, feed.throat_run, feed.throat_run] ]; Pfeed_neg = [ -[cpw.center_w/2+cpw.gap, board.width/2, board.width/2, cpw.center_w/2+cpw.gap] ; ... [0, 0, feed.throat_run, feed.throat_run] ]; CSX = AddPolygon(CSX, 'copper', 10, 2, substrate.thickness, Pfeed_pos, 'CoordSystem', 0); CSX = AddPolygon(CSX, 'copper', 10, 2, substrate.thickness, Pfeed_neg, 'CoordSystem', 0); start = [ cpw.center_w/2, 0, substrate.thickness]; stop = [ cpw.center_w/2+cpw.gap, 0.1, substrate.thickness]; [CSX, port] = AddLumpedPort(CSX, 15, 1, feed.R_ref, start, stop, [1 0 0], true); mesh = DetectEdges(CSX, mesh, 'ExcludeProperty', {'copper'}); mesh = DetectEdges(CSX, mesh, 'SetProperty', {'copper'}, '2D_Metal_Edge_Res', c0/(f_high)/unit/20); pre_tol = 0.15; mesh.x = sort(mesh.x); mesh.x = mesh.x([true diff(mesh.x) > pre_tol]); mesh.y = sort(mesh.y); mesh.y = mesh.y([true diff(mesh.y) > pre_tol]); mesh.z = sort(mesh.z); mesh.z = mesh.z([true diff(mesh.z) > pre_tol]); mesh = SmoothMesh(mesh, c0/(f_high)/unit/10); merge_tol = 1e-2; mesh.x = sort(mesh.x); mesh.x = mesh.x([true diff(mesh.x) > merge_tol]); mesh.y = sort(mesh.y); mesh.y = mesh.y([true diff(mesh.y) > merge_tol]); mesh.z = sort(mesh.z); mesh.z = mesh.z([true diff(mesh.z) > merge_tol]); CSX = DefineRectGrid(CSX, unit, mesh); start = [mesh.x(2) mesh.y(2) mesh.z(2)]; stop = [mesh.x(end-3) mesh.y(end-3) mesh.z(end-3)]; [CSX, nf2ff] = CreateNF2FFBox(CSX, 'nf2ff', start, stop); Sim_Path = sprintf('Sweep_L%d_ya%d', taper.L, taper.ya); Sim_CSX = 'VIV.xml'; [status, message, messageid] = rmdir(Sim_Path, 's'); [status, message, messageid] = mkdir(Sim_Path); WriteOpenEMS([Sim_Path '/' Sim_CSX], FDTD, CSX); try RunOpenEMS(Sim_Path, Sim_CSX, '--debug-PEC'); catch err fprintf(' -> run failed/interrupted: %s\n', err.message); end try port = calcPort(port, Sim_Path, freq); s11dB = 20*log10(abs(port.uf.ref ./ port.uf.inc)); worst = max(s11dB(band_idx)); [best_val, best_ix] = min(s11dB); converged = 1; % we don't parse the solver log here; verify manually for the winner results = [results; taper.L taper.ya worst best_val freq(best_ix)/1e6 converged]; %#ok fprintf(' -> worst-case S11 in 850-2000 MHz band: %.2f dB | deepest dip: %.2f dB @ %.0f MHz\n', ... worst, best_val, freq(best_ix)/1e6); catch err fprintf(' -> post-processing failed: %s\n', err.message); results = [results; taper.L taper.ya NaN NaN NaN 0]; %#ok end end fprintf('\n\n========== SWEEP SUMMARY (sorted best-first) ==========\n'); fprintf('%8s %8s %18s %14s %12s\n', 'taper.L', 'taper.ya', 'worst S11 (dB)', 'deepest dip', 'at freq(MHz)'); [~, order] = sort(results(:,3)); % ascending worst-case S11 (most negative = best) for i = 1:size(results,1) r = results(order(i),:); fprintf('%8d %8d %18.2f %14.2f %12.0f\n', r(1), r(2), r(3), r(4), r(5)); end best = results(order(1),:); fprintf('\nBEST combination: taper.L=%d mm, taper.ya=%d mm (worst-case S11 = %.2f dB across 850-2000 MHz)\n', ... best(1), best(2), best(3)); fprintf('IMPORTANT: this used the coarse exploration mesh and a reduced NrTs cap (%d) for speed.\n', NrTsCap); fprintf('Re-run this exact combination in Vivaldi_OpenEMS_Start.m (fine mesh, full NrTs) to confirm\n'); fprintf('before treating it as your final design.\n');