Template_Lowpass_1_Para.py

# -*- coding: utf-8 -*-
"""
Created on Mon Oct 19 15:02:27 2020

@author: Marc Bodem

Template for Calling CST from Python
- Lowpass Filter (Design Studio)
- Parameter Sweep (load only one sample point at a time)
- change one parameter at a time
- Obtain S-Parameter values

"""
import sys
sys.path.append(r"C:\Program Files (x86)\CST Studio Suite 2020\AMD64\python_cst_libraries")
import cst
import cst.interface
import cst.results
import numpy as np
import time
import shutil

start = time.time()

# Local path to CST project file --> Please adapt
cst_path = r'D:\Documents\Vorlagen\CST_Python_Interface' # path
cst_project = '\S-Parameter Lowpass' # CST project

cst_project_path = cst_path + cst_project + '.cst'
cst_result_folder = cst_path + cst_project + '\Result'


# Delete all old results (if exist)
try:
    shutil.rmtree(cst_result_folder)
except OSError as e:
    print(e)
else:
    print("The results directory is deleted successfully")


# Define parameter value for change
sample_point = 6.8


# Define list with frequency points of interest, here 0-7 GHz, Number of calculated points are set to 7001 in CST file, to get the desired frequencies.
freq_range = [0,1,2,3,4,5,6,7]
freq_range_pos = np.array(freq_range)*1000


# Initialize lists with S-parameter results
S_all = []
S_real_all = []
S_imag_all = []
SdB_all = []


# Open CST as software
mycst=cst.interface.DesignEnvironment()

# Open CST Project
mycst1=cst.interface.DesignEnvironment.open_project(mycst,cst_project_path)

#Delete All Sequences before starting to get a fresh file
delete ='Sub Main() \n ParameterSweep.DeleteAllSequences() \nEnd Sub'
mycst1.schematic.execute_vba_code(delete, timeout=None)


#VBA Add Sequence
createSequence = 'Sub Main () \n ParameterSweep.AddSequence("Seq1") \n End Sub' 
#VBA Add Parameters to Sequence. For each Parameter combination you want to test, create 1 sequence
add_Para_L1 = 'Sub Main () \n ParameterSweep.AddParameter("Seq1","L1",'+str(True)+','+str(sample_point)+','+str(sample_point)+','+str(1)+') \n End Sub'
   
#excute VBA Code above
mycst1.schematic.execute_vba_code(createSequence, timeout=None)
mycst1.schematic.execute_vba_code(add_Para_L1, timeout=None)
   
   
#Start Solver
solve = 'Sub Main () \n ParameterSweep.Start \nEnd Sub'
mycst1.schematic.execute_vba_code(solve, timeout=None)

#Delete All Sequences
mycst1.schematic.execute_vba_code(delete, timeout=None)

#get Project for results
project = cst.results.ProjectFile(cst_project_path, allow_interactive=True)

#get schamatic
schematic = project.get_schematic()

#get the actual results
results = schematic.get_result_item('Tasks\\SPara1\\S-Parameters\\S2,1')

#get frequencies
freqs = np.array(results.get_xdata())

#get S21 Parameter
S_Para = np.array(results.get_ydata())

# Initialize value list for one MC sample point over all frequency points
freq_pos = []
freq = []
S = []
SdB = []
S_real = []
S_imag = []
    
    
# Get results for each freq. point of interest from CST
for j in range(len(freq_range)):
    freq_pos_j = freq_range_pos[j]
    freq_pos.append(freq_pos_j)
        
    freq_value_j = freqs[freq_pos_j]
    freq.append(freq_value_j)
        
    S_real_j = S_Para[freq_pos_j].real
    S_real.append(S_real_j)
        
    S_imag_j = S_Para[freq_pos_j].imag
    S_imag.append(S_imag_j)
        
    S_j=np.sqrt(S_real_j**2+S_imag_j**2)
    S.append(S_j)
        
    S_dB_j = 20*np.log10(S_j)
    SdB.append(S_dB_j)
    

#close CST
cst.interface.DesignEnvironment.close(mycst) 
    
# Return results
print('\n frequency range in GHz:', freq_range)
print('frequency range as positions in CST:', freq_pos)
print('S-parameter:',S)
print('S-parameter (real part):',S_real)
print('S-parameter (imag part):',S_imag)
print('S-parameter (in dB):',SdB)

# Return runtime
end = time.time()
print('\n Runtime: {:5.3f}seconds'.format(end-start))