matthuszagh / pyems

Taper implementation is incomplete. According to the code (

Line 1815 in f63fcf8

construct_polygon(

) the polygons themselves are being created, but they are not being appended to the polygon list.

I think I see what you're saying, but it would be helpful if you could provide a reproducible example that shows incorrect behavior. It's been a couple years since I wrote this code, so that would help me be sure I'm changing things in the intended way.

Hey, sorry for the late answer, been busy tweaking simulations here and there. Here's the reproducer: it is basically two microstrips with a taper in the middle you can conditionally disable. The problem arises when you attempt to save the footprint: as the Taper does not append these polygons to the polygon list, it breaks with an exception:

#!/usr/bin/env python3

#
# Set these to False to disable addition of the taper section and
# generation of the footprint respectively
#

ADD_TAPER       = True
WRITE_FOOTPRINT = True

import os
import sys
import numpy as np
from pyems.structure import Microstrip, PCB, MicrostripCoupler, Taper
from pyems.simulation import Simulation
from pyems.pcb import common_pcbs
from pyems.calc import phase_shift_length, microstrip_effective_dielectric
from pyems.utilities import print_table
from pyems.coordinate import Coordinate2, Axis, Box3, Coordinate3
from pyems.mesh import Mesh
from pyems.field_dump import FieldDump, DumpType
from pyems.kicad import write_footprint_set

freq = np.linspace(0e9, 18e9, 501)
ref_freq = 5.6e9
unit = 1e-3
sim = Simulation(freq=freq, unit=unit, reference_frequency=ref_freq)

pcb_prop = common_pcbs["oshpark4"]
trace_width = 0.38
trace_spacing = 0.2
eeff = microstrip_effective_dielectric(
    pcb_prop.substrate.epsr_at_freq(ref_freq),
    substrate_height=pcb_prop.substrate_thickness(0, unit=unit),
    trace_width=trace_width,
)
coupler_length = phase_shift_length(90, eeff, ref_freq)
pcb_len = 2 * coupler_length
pcb_width = 0.5 * pcb_len
pcb = PCB(
    sim=sim,
    pcb_prop=pcb_prop,
    length=pcb_len,
    width=pcb_width,
    layers=range(3),
    omit_copper=[0],
)

structures = []

port0_x = 0
port0_y = 0

s1 = Microstrip(
    pcb=pcb,
    position=Coordinate2(np.average([port0_x, -pcb_len / 2]), port0_y),
    length=port0_x + pcb_len / 2,
    width=trace_width,
    propagation_axis=Axis("x"),
    port_number=1,
    excite=True,
    ref_impedance=50,
    feed_shift=0.3,
)

structures.append(s1)

port1_x = 0
port1_y = 0
s2 = Microstrip(
    pcb=pcb,
    position=Coordinate2(np.average([port1_x, pcb_len / 2]), port0_y),
    length=pcb_len / 2 - port1_x,
    width=trace_width,
    propagation_axis=Axis("x", direction=-1),
    port_number=2,
    excite=False,
    ref_impedance=50,
)

structures.append(s2)

if ADD_TAPER:
    taper_len = pcb_width / 3
    taper = Taper(
        pcb = pcb,
        position = Coordinate2(taper_len / 2, 0),
        pcb_layer = 0,
        width1 = trace_width,
        width2 = trace_width * 4,
        length = taper_len,
        rotation = 90),

    structures.append(taper)
    
Mesh(
    sim=sim,
    metal_res=1 / 120,
    nonmetal_res=1 / 40,
    smooth=(1.1, 1.5, 1.5),
    min_lines=3,
    expand_bounds=((0, 0), (0, 0), (10, 20)),
)

FieldDump(
    sim=sim,
    box=Box3(
        Coordinate3(-pcb_len / 2, -pcb_width / 2, 0),
        Coordinate3(pcb_len / 2, pcb_width / 2, 0),
    ),
    dump_type=DumpType.current_density_time,
)


if WRITE_FOOTPRINT:
    write_footprint_set(structures, "coupler_20db", "coupler_20db.kicad_mod")

sim.run(csx = True)

This should now be fixed in ff563e8. Feel free to reopen if you run into any issues.

Taper is half implemented