# -*- coding: utf-8 -*- ### Import Libraries import os, tempfile from pylab import * import csv from CSXCAD import ContinuousStructure from openEMS import openEMS from openEMS.physical_constants import * from pathlib import Path import pandas as pd import numpy as np import skrf as rf ### Setup the simulation Sim_Path = os.path.join(os.getcwd(), 'MSL20') post_proc_only = False unit = 1e-6 # specify everything in um MSL_length = 8000 #MSL_length = 4000 MSL_width = 450 substrate_thickness = 203 substrate_width=8000 substrate_epr = 3.55 #stub_length = 12e3 f_max = 20e9 ### Setup FDTD parameters & excitation function FDTD = openEMS() FDTD.SetGaussExcite( f_max/2, f_max/2 ) FDTD.SetBoundaryCond( ['PML_8', 'PML_8', 'MUR', 'MUR', 'PEC', 'MUR'] ) ### Setup Geometry & Mesh CSX = ContinuousStructure() FDTD.SetCSX(CSX) mesh = CSX.GetGrid() mesh.SetDeltaUnit(unit) resolution = C0/(f_max*sqrt(substrate_epr))/unit/50 # resolution of lambda/50 third_mesh = array([2*resolution/3, -resolution/3])/4 ## Do manual meshing #mesh.AddLine('x', 0) #mesh.AddLine('x', MSL_width/2+third_mesh) #mesh.AddLine('x', -MSL_width/2-third_mesh) #mesh.SmoothMeshLines('x', resolution/2) mesh.AddLine('x', 0) #mesh.AddLine('x', MSL_width/2+third_mesh) #mesh.AddLine('x', -MSL_width/2-third_mesh) mesh.AddLine('x', [-MSL_length/2, MSL_length/2]) mesh.SmoothMeshLines('x', resolution/2) mesh.AddLine('y', 0) mesh.AddLine('y', MSL_width/2+third_mesh) mesh.AddLine('y', -MSL_width/2-third_mesh) mesh.SmoothMeshLines('y', resolution/4) #mesh.AddLine('y', [-15*MSL_width, 15*MSL_width]) mesh.AddLine('y', [-substrate_width/2, substrate_width/2]) mesh.AddLine('y', (MSL_width/2)) mesh.SmoothMeshLines('y', resolution) mesh.AddLine('z', linspace(0,substrate_thickness,5)) mesh.AddLine('z', 3000) mesh.SmoothMeshLines('z', resolution) ## Add the substrate substrate = CSX.AddMaterial( 'RO4350B', epsilon=substrate_epr) start = [-MSL_length/2, -substrate_width/2, 0] stop = [+MSL_length/2, substrate_width/2, substrate_thickness] substrate.AddBox(start, stop ) ###Add the gnd plane """ gndp = CSX.AddMetal( 'PEC' ) startg = [-MSL_length, -15*MSL_width, 0] stopg = [ +MSL_length, +15*MSL_width, 0] gndp.AddBox(startg, stopg, priority=10 ) """ ### add gnd as a conducting sheet pec = CSX.AddConductingSheet('PEC', conductivity=59.6e6, thickness=35e-6) startg = [-MSL_length/2, -substrate_width/2, 0] stopg = [ +MSL_length/2, +substrate_width/2, 0] pec.AddBox(startg, stopg, priority=10 ) ## MSL Definition topC = CSX.AddConductingSheet( 'copper' , conductivity=59.6e6, thickness=35e-6) startp = [-MSL_length/2, -MSL_width/2, substrate_thickness] stopp = [ MSL_length/2, +MSL_width/2, substrate_thickness] topC.AddBox(startp, stopp, priority=10 ) """ Original pec = CSX.AddConductingSheet( 'PEC' , conductivity=59.6e6, thickness=35e-6) startp = [-MSL_width/2, MSL_width/2, substrate_thickness] stopp = [ MSL_width/2, MSL_width/2, substrate_thickness] pec.AddBox(startp, stopp, priority=10 ) """ ## MSL port setup port = [None, None] portstarta = [ -MSL_length/2, -MSL_width/2, substrate_thickness] portstopa = [ -MSL_length/4, MSL_width/2, 0] #port[0] = FDTD.AddMSLPort( 1, pec, portstarta, portstopa, 'x', 'z', excite=-1, FeedShift=10*resolution, MeasPlaneShift=-MSL_length/6, priority=10) port[0] = FDTD.AddMSLPort( 1, topC, portstarta, portstopa, 'x', 'z', excite=-1,FeedShift=10*resolution, MeasPlaneShift=MSL_length/4, priority=10) portstartb = [+MSL_length/2, -MSL_width/2, substrate_thickness] portstopb = [+MSL_length/4 , MSL_width/2, 0] #port[1] = FDTD.AddMSLPort( 2, topC, portstartb, portstopb, 'x', 'z', MeasPlaneShift=MSL_length/4, priority=10 ) port[1] = FDTD.AddMSLPort( 2, topC, portstartb, portstopb, 'x', 'z', excite=-1, FeedShift=10*resolution, MeasPlaneShift=MSL_length/4, priority=10) ### Run the simulation if 0: # debugging only CSX_file = os.path.join(Sim_Path, 'MSL20.xml') if not os.path.exists(Sim_Path): os.mkdir(Sim_Path) CSX.Write2XML(CSX_file) from CSXCAD import AppCSXCAD_BIN os.system(AppCSXCAD_BIN + ' "{}"'.format(CSX_file)) if not post_proc_only: FDTD.Run(Sim_Path, cleanup=True) CSX_file = os.path.join(Sim_Path, 'MSL20.xml') CSX.Write2XML(CSX_file) from CSXCAD import AppCSXCAD_BIN os.system(AppCSXCAD_BIN + ' "{}"'.format(CSX_file)) freq = rf.Frequency(start=1, stop=20, npoints=1601, unit='ghz') ### Post-processing and plotting #f = rf.Frequency(start=1, stop=10, npoints=101, unit='ghz') #original f = linspace( 1e9, f_max, 1601 ) for p in port: p.CalcPort( Sim_Path, f, ref_impedance = 50) s11 = port[0].uf_ref / port[0].uf_inc s21 = port[1].uf_ref / port[0].uf_inc s22 = port[1].uf_ref / port[1].uf_inc s12 = port[0].uf_ref / port[1].uf_inc A = ((1+s11)*(1-s11) + s21*s21)/(2*s21); B = port[0].Z_ref*((1+s11)*(1-s11) - s21*s21)/(2*s21); C = ((1-s11)*(1-s11) - s21*s21)/(2*s21) / port[1].Z_ref; #C = ((1-s11)*(1-s22) - s21*s21)/(2*s21) / 50 D = ((1+s11)*(1-s22) + s21*s12)/(2*s21); #D= ((1+s11)*(1-s22) + s21*s12)/(2*s21)/ 50 Zo_calc=sqrt(B/C); s11_real=s11.real; s11_imag=s11.imag; s21_real=s21.real; s21_imag=s21.imag; s12_real=s12.real; s12_imag=s12.imag; s22_real=s22.real; s22_imag=s22.imag; # Create a plot #plt.figure(figsize=(10, 6)) # Optional: set figure size plt.plot(f, 20*log10(abs(s11)), 'k-', f, 20*log10(abs(s21)), 'r-', f,20*log10(abs(s22)), 'b-',f,20*log10(abs(s12)),'g-',linewidth = 8) # Example: line plt.legend(["S11", "S21", "S22", "S12"], loc="upper right") # Add labels and title plt.xlabel('Frequency',fontsize=20) plt.ylabel('Sparam(dB)',fontsize=20) plt.title('Sparams',fontsize=20) plt.grid(True) # Optional: add a grid plt.xlim(0, 20e9) # Set x-axis limit from 0 to 20 #plt.ylim(-45,100) # Display the plot plt.show()