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Diffstat (limited to 'openEMS/python/Tutorials/Bent_Patch_Antenna.py')
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diff --git a/openEMS/python/Tutorials/Bent_Patch_Antenna.py b/openEMS/python/Tutorials/Bent_Patch_Antenna.py new file mode 100644 index 0000000..ef2cb0e --- /dev/null +++ b/openEMS/python/Tutorials/Bent_Patch_Antenna.py @@ -0,0 +1,198 @@ +# -*- coding: utf-8 -*- +""" + Bent Patch Antenna Tutorial + + Tested with + - python 3.4 + - openEMS v0.0.33+ + + (C) 2016 Thorsten Liebig <thorsten.liebig@gmx.de> + +""" + +### Import Libraries +import os, tempfile +from pylab import * +from mpl_toolkits.mplot3d import Axes3D + +from CSXCAD import CSXCAD + +from openEMS.openEMS import openEMS +from openEMS.physical_constants import * + + +### Setup the simulation +Sim_Path = os.path.join(tempfile.gettempdir(), 'Bent_Patch') + +post_proc_only = False + +unit = 1e-3 # all length in mm + +f0 = 2.4e9 # center frequency, frequency of interest! +lambda0 = round(C0/f0/unit) # wavelength in mm +fc = 0.5e9 # 20 dB corner frequency + +# patch width in alpha-direction +patch_width = 32 # resonant length in alpha-direction +patch_radius = 50 # radius +patch_length = 40 # patch length in z-direction + +#substrate setup +substrate_epsR = 3.38 +substrate_kappa = 1e-3 * 2*pi*2.45e9 * EPS0*substrate_epsR +substrate_width = 80 +substrate_length = 90 +substrate_thickness = 1.524 +substrate_cells = 4 + +#setup feeding +feed_pos = -5.5 #feeding position in x-direction +feed_width = 2 #feeding port width +feed_R = 50 #feed resistance + +# size of the simulation box +SimBox_rad = 2*100 +SimBox_height = 1.5*200 + +### Setup FDTD parameter & excitation function +FDTD = openEMS(CoordSystem=1) # init a cylindrical FDTD +f0 = 2e9 # center frequency +fc = 1e9 # 20 dB corner frequency +FDTD.SetGaussExcite(f0, fc) +FDTD.SetBoundaryCond(['MUR', 'MUR', 'MUR', 'MUR', 'MUR', 'MUR']) # boundary conditions + +### Setup the Geometry & Mesh +# init a cylindrical mesh +CSX = CSXCAD.ContinuousStructure(CoordSystem=1) +FDTD.SetCSX(CSX) +mesh = CSX.GetGrid() +mesh.SetDeltaUnit(unit) + +### Setup the geometry using cylindrical coordinates +# calculate some width as an angle in radiant +patch_ang_width = patch_width/(patch_radius+substrate_thickness) +substr_ang_width = substrate_width/patch_radius +feed_angle = feed_pos/patch_radius + +# create patch +patch = CSX.AddMetal('patch') # create a perfect electric conductor (PEC) +start = [patch_radius+substrate_thickness, -patch_ang_width/2, -patch_length/2 ] +stop = [patch_radius+substrate_thickness, patch_ang_width/2, patch_length/2 ] +CSX.AddBox(patch, priority=10, start=start, stop=stop, edges2grid='all') # add a box-primitive to the metal property 'patch' + +# create substrate +substrate = CSX.AddMaterial('substrate', epsilon=substrate_epsR, kappa=substrate_kappa ) +start = [patch_radius , -substr_ang_width/2, -substrate_length/2] +stop = [patch_radius+substrate_thickness, substr_ang_width/2, substrate_length/2] +substrate.AddBox(start=start, stop=stop, edges2grid='all') + +# save current density oon the patch +jt_patch = CSX.AddDump('Jt_patch', dump_type=3, file_type=1) +start = [patch_radius+substrate_thickness, -substr_ang_width/2, -substrate_length/2] +stop = [patch_radius+substrate_thickness, +substr_ang_width/2, substrate_length/2] +jt_patch.AddBox(start=start, stop=stop) + +# create ground +gnd = CSX.AddMetal('gnd') # create a perfect electric conductor (PEC) +start = [patch_radius, -substr_ang_width/2, -substrate_length/2] +stop = [patch_radius, +substr_ang_width/2, +substrate_length/2] +gnd.AddBox(priority=10, start=start, stop=stop, edges2grid='all') + +# apply the excitation & resist as a current source +start = [patch_radius , feed_angle, 0] +stop = [patch_radius+substrate_thickness, feed_angle, 0] +port = FDTD.AddLumpedPort(1 ,feed_R, start, stop, 'r', 1.0, priority=50, edges2grid='all') + +### Finalize the Mesh +# add the simulation domain size +mesh.AddLine('r', patch_radius+np.array([-20, SimBox_rad])) +mesh.AddLine('a', [-0.75*pi, 0.75*pi]) +mesh.AddLine('z', [-SimBox_height/2, SimBox_height/2]) + +# add some lines for the substrate +mesh.AddLine('r', patch_radius+np.linspace(0,substrate_thickness,substrate_cells)) + +# generate a smooth mesh with max. cell size: lambda_min / 20 +max_res = C0 / (f0+fc) / unit / 20 +max_ang = max_res/(SimBox_rad+patch_radius) # max res in radiant +mesh.SmoothMeshLines(0, max_res, 1.4) +mesh.SmoothMeshLines(1, max_ang, 1.4) +mesh.SmoothMeshLines(2, max_res, 1.4) + +## Add the nf2ff recording box +nf2ff = FDTD.CreateNF2FFBox() + +### Run the simulation +if 0: # debugging only + CSX_file = os.path.join(Sim_Path, 'bent_patch.xml') + if not os.path.exists(Sim_Path): + os.mkdir(Sim_Path) + CSX.Write2XML(CSX_file) + os.system(r'AppCSXCAD "{}"'.format(CSX_file)) + + +if not post_proc_only: + FDTD.Run(Sim_Path, verbose=3, cleanup=True) + +### Postprocessing & plotting +f = np.linspace(max(1e9,f0-fc),f0+fc,401) +port.CalcPort(Sim_Path, f) +Zin = port.uf_tot / port.if_tot +s11 = port.uf_ref/port.uf_inc +s11_dB = 20.0*np.log10(np.abs(s11)) + +figure() +plot(f/1e9, s11_dB) +grid() +ylabel('s11 (dB)') +xlabel('frequency (GHz)') + +P_in = 0.5*np.real(port.uf_tot * np.conj(port.if_tot)) # antenna feed power + +# plot feed point impedance +figure() +plot( f/1e6, real(Zin), 'k-', linewidth=2, label=r'$\Re(Z_{in})$' ) +grid() +plot( f/1e6, imag(Zin), 'r--', linewidth=2, label=r'$\Im(Z_{in})$' ) +title( 'feed point impedance' ) +xlabel( 'frequency (MHz)' ) +ylabel( 'impedance ($\Omega$)' ) +legend( ) + + +idx = np.where((s11_dB<-10) & (s11_dB==np.min(s11_dB)))[0] +if not len(idx)==1: + print('No resonance frequency found for far-field calulation') +else: + f_res = f[idx[0]] + theta = np.arange(-180.0, 180.0, 2.0) + print("Calculate NF2FF") + nf2ff_res_phi0 = nf2ff.CalcNF2FF(Sim_Path, f_res, theta, 0, center=np.array([patch_radius+substrate_thickness, 0, 0])*unit, read_cached=True, outfile='nf2ff_xz.h5') + + figure(figsize=(15, 7)) + ax = subplot(121, polar=True) + E_norm = 20.0*np.log10(nf2ff_res_phi0.E_norm/np.max(nf2ff_res_phi0.E_norm)) + nf2ff_res_phi0.Dmax + ax.plot(np.deg2rad(theta), 10**(np.squeeze(E_norm)/20), linewidth=2, label='xz-plane') + ax.grid(True) + ax.set_xlabel('theta (deg)') + ax.set_theta_zero_location('N') + ax.set_theta_direction(-1) + ax.legend(loc=3) + + phi = theta + nf2ff_res_theta90 = nf2ff.CalcNF2FF(Sim_Path, f_res, 90, phi, center=np.array([patch_radius+substrate_thickness, 0, 0])*unit, read_cached=True, outfile='nf2ff_xy.h5') + + ax = subplot(122, polar=True) + E_norm = 20.0*np.log10(nf2ff_res_theta90.E_norm/np.max(nf2ff_res_theta90.E_norm)) + nf2ff_res_theta90.Dmax + ax.plot(np.deg2rad(phi), 10**(np.squeeze(E_norm)/20), linewidth=2, label='xy-plane') + ax.grid(True) + ax.set_xlabel('phi (deg)') + suptitle('Bent Patch Anteanna Pattern\nFrequency: {} GHz'.format(f_res/1e9), fontsize=14) + ax.legend(loc=3) + + print( 'radiated power: Prad = {:.2e} Watt'.format(nf2ff_res_theta90.Prad[0])) + print( 'directivity: Dmax = {:.1f} ({:.1f} dBi)'.format(nf2ff_res_theta90.Dmax[0], 10*np.log10(nf2ff_res_theta90.Dmax[0]))) + print( 'efficiency: nu_rad = {:.1f} %'.format(100*nf2ff_res_theta90.Prad[0]/real(P_in[idx[0]]))) + +show() + |