Month: March 2018

I am not very sure if I am doing one port calibration correctly using scikit-rf.

import skrf as rf
from skrf.plotting import save_all_figs
from skrf.calibration import OnePort

my_ideals = rf.read_all('ideals/')
my_measured = rf.read_all('measured/')
dut = rf.Network('sma_8dB.s1p')

cal = rf.OnePort(
    ideals   = [my_ideals  [k] for k in ['sma_short', 'sma_open', 'sma_50ohm']],
    measured = [my_measured[k] for k in ['sma_short', 'sma_open', 'sma_50ohm']],
    )

caled_dut = cal.apply_cal(dut)

caled_dut.plot_s_smith()
#caled_dut.plot_s_db()
#caled_dut.plot_z_im()
#caled_dut.plot_z_im()

save_all_figs('./', format=['png'])

$ ls -l ./ideals/ ./measured/
./ideals/:
total 24
-rw-r--r--  1 user1  staff  869 Mar 31 20:02 sma_50ohm.s1p
-rw-r--r--  1 user1  staff  869 Mar 31 20:04 sma_open.s1p
-rw-r--r--  1 user1  staff  970 Mar 31 20:07 sma_short.s1p

./measured/:
total 32
-rw-r--r--  1 user1  staff  2686 Mar 31 20:13 sma_50ohm.s1p
-rw-r--r--  1 user1  staff  2450 Mar 31 20:13 sma_8dB.s1p
-rw-r--r--  1 user1  staff  2426 Mar 31 20:13 sma_open.s1p
-rw-r--r--  1 user1  staff  2337 Mar 31 20:13 sma_short.s1p

$ head ./ideals/sma_50ohm.s1p ./measured/sma_50ohm.s1p 
==> ./ideals/sma_50ohm.s1p <==
# MHz S RI R 50
0 0 0
0.3 0 0
0.6 0 0
0.9 0 0
1.2 0 0
1.5 0 0
1.8 0 0
2.1 0 0
2.4 0 0

==> ./measured/sma_50ohm.s1p <==
# MHz S RI R 50
0 0.00701499 0.00504031
0.3 0.00701499 0.00504031
0.6 0.00701499 0.00504031
0.9 0.00878989 0.0028871
1.2 0.00932459 0.00274434
1.5 0.00956452 0.00248623
1.8 0.01028 0.00211041
2.1 0.0100815 0.00206556
2.4 0.0127909 0.00148593

Are these better than uncalibrated ones?

I suppose I should cut off the legs, but they are only for the HF band.

Open

Short

Match

With the above three measurements, I should be able calibrate the system.
http://emlab.uiuc.edu/ece451/appnotes/Rytting_NAModels.pdf

This is before calibration with my 4dB attenuator.

Since the output of the attenuator is open, the return loss shall be twice the attenuation of each section, namely, 0.5dB, 1dB, 2dB, 3dB, 4dB, 10dB and 20dB.

Note that no calibration is tried. Just showing the raw data.

I suppose all the components are mounted correctly.

DC characteristics seems to be OK.

You can share your images using Docker Hub.

The above figure shows that seven containers are running on two virtual machines.

The image mytest:part1 is pulled from my public repository Spinorlab/mytest.

$ docker version
Client:
 Version:	18.03.0-ce
 API version:	1.37
 Go version:	go1.9.4
 Git commit:	0520e24
 Built:	Wed Mar 21 23:06:22 2018
 OS/Arch:	darwin/amd64
 Experimental:	false
 Orchestrator:	swarm

Server:
 Engine:
  Version:	18.03.0-ce
  API version:	1.37 (minimum version 1.12)
  Go version:	go1.9.4
  Git commit:	0520e24
  Built:	Wed Mar 21 23:14:32 2018
  OS/Arch:	linux/amd64
  Experimental:	true

$ docker run -it ubuntu bash
Unable to find image 'ubuntu:latest' locally
latest: Pulling from library/ubuntu
22dc81ace0ea: Pull complete 
1a8b3c87dba3: Pull complete 
91390a1c435a: Pull complete 
07844b14977e: Pull complete 
b78396653dae: Pull complete 
Digest: sha256:e348fbbea0e0a0e73ab0370de151e7800684445c509d46195aef73e090a49bd6
Status: Downloaded newer image for ubuntu:latest

root@1001c7458899:/# uname -a
Linux 1001c7458899 4.9.87-linuxkit-aufs #1 SMP Wed Mar 14 15:12:16 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

The components in the XML file do not always appear in numerical order, therefore I modified the python program slightly.

# coding: utf-8
import xml.etree.ElementTree as ET
import re
from operator import itemgetter

print('"型番","メーカー名","数量"')

tree = ET.parse('RF-ATT.xml')
root = tree.getroot()

regex = r'R[0-9]+'
list = []

for node in root.iter('comp'):
	name = node.attrib.get('ref')
	if re.search(regex, name):
		for value in node.iter('value'):
			ref = int(name.replace('R', '0'))
			list.append([ref,value.text])

list.sort()

for i in range(len(list)):
	string = '1/4WキンピR '+list[i][1]+'Ω,KOA,1'
	print(string)

By using two resistors in parallel you can improve the precision of the attenuators.

The BOM for the above figure is:

% python xml2bom.py | nkf -s > BOM.csv
% cat BOM.csv | nkf -w
"型番","メーカー名","数量"
1/4WキンピR 8.2KΩ,KOA,1
1/4WキンピR 4.7Ω,KOA,1
1/4WキンピR 7.5Ω,KOA,1
1/4WキンピR 2.2KΩ,KOA,1
1/4WキンピR 6.8KΩ,KOA,1
1/4WキンピR 6.8Ω,KOA,1
1/4WキンピR 39Ω,KOA,1
1/4WキンピR 1KΩ,KOA,1
1/4WキンピR 2KΩ,KOA,1
1/4WキンピR 15Ω,KOA,1
1/4WキンピR 51Ω,KOA,1
1/4WキンピR 560Ω,KOA,1
1/4WキンピR 910Ω,KOA,1
1/4WキンピR 27Ω,KOA,1
1/4WキンピR 51Ω,KOA,1
1/4WキンピR 430Ω,KOA,1
1/4WキンピR 220Ω,KOA,1
1/4WキンピR 220Ω,KOA,1
1/4WキンピR 24Ω,KOA,1
1/4WキンピR 270Ω,KOA,1
1/4WキンピR 270Ω,KOA,1
1/4WキンピR 91Ω,KOA,1
1/4WキンピR 330Ω,KOA,1
1/4WキンピR 150Ω,KOA,1
1/4WキンピR 150Ω,KOA,1
1/4WキンピR 240Ω,KOA,1
1/4WキンピR 240Ω,KOA,1
1/4WキンピR 390Ω,KOA,1
1/4WキンピR 680Ω,KOA,1
1/4WキンピR 82Ω,KOA,1
1/4WキンピR 82Ω,KOA,1
1/4WキンピR 8.2KΩ,KOA,1
1/4WキンピR 2.2KΩ,KOA,1
1/4WキンピR 6.8KΩ,KOA,1
1/4WキンピR 1KΩ,KOA,1
1/4WキンピR 2KΩ,KOA,1
1/4WキンピR 560Ω,KOA,1
1/4WキンピR 910Ω,KOA,1
1/4WキンピR 430Ω,KOA,1

In the XML file, components do not appear in numerical order, perhaps due to reflecting past editing histories.

% egrep 'comp.*R[0-9]+' RF-ATT.xml 
    <comp ref="R2">
    <comp ref="R3">
    <comp ref="R4">
    <comp ref="R1">
    <comp ref="R8">
    <comp ref="R9">
    <comp ref="R10">
    <comp ref="R7">
    <comp ref="R14">
    <comp ref="R15">
    <comp ref="R16">
    <comp ref="R13">
    <comp ref="R20">
    <comp ref="R21">
    <comp ref="R22">
    <comp ref="R19">
    <comp ref="R25">
    <comp ref="R27">
    <comp ref="R26">
    <comp ref="R29">
    <comp ref="R32">
    <comp ref="R30">
    <comp ref="R31">
    <comp ref="R28">
    <comp ref="R33">
    <comp ref="R35">
    <comp ref="R38">
    <comp ref="R36">
    <comp ref="R37">
    <comp ref="R34">
    <comp ref="R39">
    <comp ref="R5">
    <comp ref="R6">
    <comp ref="R11">
    <comp ref="R12">
    <comp ref="R17">
    <comp ref="R18">
    <comp ref="R23">
    <comp ref="R24">

Sorting the list is an easy job, but I do not know if it is worth trying.

Marutsu is an electronics component vendor in Japan. They accept BOM files in the following format;

It seems that they only understand Japanese language encoded in Shift_JIS. This is somewhat unfortunate, but the basic idea is always the same.

# coding: utf-8
import xml.etree.ElementTree as ET
import re

print('"型番","メーカー名","数量"')

tree = ET.parse('RF-ATT.xml')
root = tree.getroot()

regex = r'R[0-9]+'

for node in root.iter('comp'):
	name = node.attrib.get('ref')
	if re.search(regex, name):
		for value in node.iter('value'):
			string = '1/4WキンピR '+value.text+'Ω,KOA,1'
			print(string)

This is a python program that converts the XML file (intermediate net list) from KiCad to a BOM file to be uploaded to Marutsu.

% python xml2bom.py | nkf -s > BOM.csv
$ cat BOM.csv | nkf -w
"型番","メーカー名","数量"
1/4WキンピR 1.8KΩ,KOA,1
1/4WキンピR 1.8KΩ,KOA,1
1/4WキンピR 3Ω,KOA,1
1/4WキンピR 910Ω,KOA,1
1/4WキンピR 910Ω,KOA,1
1/4WキンピR 5.6Ω,KOA,1
1/4WキンピR 300Ω,KOA,1
1/4WキンピR 300Ω,KOA,1
1/4WキンピR 18Ω,KOA,1
1/4WキンピR 220Ω,KOA,1
1/4WキンピR 220Ω,KOA,1
1/4WキンピR 24Ω,KOA,1
1/4WキンピR 150Ω,KOA,1
1/4WキンピR 150Ω,KOA,1
1/4WキンピR 39Ω,KOA,1
1/4WキンピR 100Ω,KOA,1
1/4WキンピR 100Ω,KOA,1
1/4WキンピR 75Ω,KOA,1
1/4WキンピR 62Ω,KOA,1
1/4WキンピR 62Ω,KOA,1
1/4WキンピR 240Ω,KOA,1

After uploading the BOM file, you will have;

and you are ready to place an order.

Let’s try creating a BOM (Bill Of Materials) file that fits your own convenience.

Firstly, export the intermediate netlist file without using any plugins.

Then, you will get an XML file something like the above.

# filename = xmlparse.pl
import xml.etree.ElementTree as ET
tree = ET.parse('RF-ATT.xml')
root = tree.getroot()

for value in root.iter('value'):
	print(value.text)

A short python program to parse an XML tree will give you the following results.

% python xmlparse.pl

Conn_Coaxial
Conn_Coaxial
SW-6P
1800
1800
3
SW-6P
910
910
5.6
SW-6P
300
300
18
SW-6P
220
220
24
SW-6P
150
150
39
SW-6P
100
100
75
SW-6P
62
62
240

Or by adding a shell script:

% xmlparse.py | sort | uniq -c

   2 100
   2 150
   1 18
   2 1800
   2 220
   1 24
   1 240
   1 3
   2 300
   1 39
   1 5.6
   2 62
   1 75
   2 910
   2 Conn_Coaxial
   7 SW-6P

This simple output may be of some use depending on the situation, but what you really wish to get is a list containing part numbers and/or part names that your favorite local parts vendor will understand.