Improved Qucs-S Attenuator Tool #722
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This commit is intented to produce more human-readable schematics Before this commit the attenuator schematics were too compact and it was difficult (or even impossible) to read the resistor values at first sight. Also, the resistor values were rounded to 1 decimal place as it is more than enough for actual attenuator design.
It was added a checkbox in the qucsatenuattor UI in order to let the user to attach a SP simulation component to the attenuator circuit. Resistive attenuators are wideband circuits so the GUI doesn't ask for a frequency sweep. The tool sets the SP sweep to 50MHz-3GHz. If needed, the user can change that before running the simulation.
It was added the reflection type synthesis to qucsattenuator. The synthesis equations can be found here: https://www.microwaves101.com/encyclopedias/reflection-attenuators
Added a new feature to the GUI to show the power dissipated by each resistor given the overall attenuation and the input power.
The QLineEdits used for the design input were replaced by QSpinBoxes. It seems to be more convenient and fluid since now the user only need to move the mouse wheel over the input to see how the resistor values move
The synthesis fails for certain Z0/att ratios in Tee and Pi type attenuators. However, success is guaranteed for the rest of attenuator types. In this sense, it makes sense to warn (in red) whenever the synthesis fails and remove the "Success" message.
This commits adds the capability to design quarter-wave series and shunt attenuators A feature for synthesizing transmission lines with lumped components (lowpass form) is also added. Reference: The PIN diode circuit designer's handbook. W.E. Doherty, Jr., R.D. Joos, Microsemi Corp., 1998 Add QW series and QW shunt attenuators This commits adds the capability to design quarter-wave series and shunt attenuators A feature for synthesizing transmission lines with lumped components (lowpass form) is also added. Reference: The PIN diode circuit designer's handbook. W.E. Doherty, Jr., R.D. Joos, Microsemi Corp., 1998
The output of the L-pad attenuator is unmatched. The output impedance is shown in a QLineEdit. The output impedance is shown in a box. The derivation of the design equations will be provided separately in the pull request
The output of the L-pad attenuators is unmatched. The output impedance is shown in a box. The derivation of the design equations will be provided separately in the pull request
The series resistor attenuator is unmatched at both ports. The input and output impedance is shown in a box. The derivation of the design equations will be provided separately in the pull request
The shunt resistor attenuator is unmatched at both ports. The input and output impedance is shown in a box. The derivation of the design equations will be provided separately in the pull request
It was added the date of this update
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Thanks for the contribution! Merged. Also thanks for technical info links. You may consider to upload it to the documentation repository #554. |
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The aim of this PR is to improve the capabilities of the RF attenuator synthesis tool.
The first seven commits were part of PR#845 (2018) in the Qucs project [1]. They remain unmerged at present, so I decided
to move them to Qucs-S. In addition to that, I have included the design unmatched resistive attenuators (Lpad, series R, shunt R attenuators)
The derivation of the design equations as well as the power dissipation equations can be found in [2].
A Qucs-S workspace [3] was used to verify the equations in [2].
Another Qucs-S workspace with tests is provided [4] as well as a spreadsheet with details of each commit and further tests.
Summary
it was hard to read the values.
Docs and links
[1] Qucs PR#845
[2] Derivation of the design equations: Notes on resistive attenuator design.odt
[3] Workspace used during the development: Qucs_Attenuator_Tool_Update_prj.zip
[4] Workspace with a number of test schematics: TESTBENCH_QucsAttenuator_Improvement_prj.zip
[5] Spreadsheet with details and tests of each commit: Improve_QucsAttenuator_Tool.ods
References
(I) RF design guide. Systems, circuits, and equations. Peter Vizmuller. Artech House, 1995
(ii) The PIN diode circuit designer's handbook. W.E. Doherty, Jr., R.D. Joos, Microsemi Corp., 1998
pin_diode_handbook.pdf