VektorFIL 1.1.1

Version 1.1.1

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

VektorFIL 1.1.0

VektorFIL 1.1.0

New

• Design files: File → Open / Save (.vfil); the last design reopens at start-up
• Report and picture: File → Export report (PDF), Save picture (PNG)
• Monte Carlo tab: runs, L and C tolerance (uniform or Gaussian), spread of S21/S11 and worst passband values
• Smith chart of S11 with impedance readout
• Time domain: step and impulse response
• Markers: click the response plot to mark S21 and S11; values in a small table
• Hover cursor on the response and group-delay plots
• Stepped stopband mask for elliptic filters, e.g. 125-200:40, 200-:60: the notches are placed so every step has the same margin
• Air-core coil calculator (Tools): turns, winding length and wire for any inductor of the design

Fixed

• Group delay no longer shows false spikes at the notches of elliptic filters
• Designs in the filter and diplexer windows can no longer interfere with each other

Install (Windows)

Run VektorFIL-1.1.0-setup.exe (per user, no admin rights), or unzip VektorFIL-1.1.0-windows.zip and run VektorFIL.exe. If SmartScreen warns, click More info → Run anyway.

User guide: https://ibelinp.github.io/vektorfil/

VektorFIL 1.0.0

VektorFIL 1.0.0

First public release of VektorFIL: interactive L-C filter and diplexer design for RF engineers and students.

Pick a response, an approximation and a circuit, type the frequencies, and the schematic and response update as you type. Underneath is real network synthesis, not lookup tables: the transfer function is computed for exactly your specification and the circuit is extracted from it at 50+ digit precision, then checked by simulation.

Filters

• Responses: lowpass, highpass, bandpass, bandstop
• Approximations: Butterworth, Chebyshev, Bessel, elliptic (including even orders, type B and C), with any ripple and any edge attenuation, up to order 25
• Singly terminated Butterworth, Chebyshev and elliptic filters
• Bandpass circuits:
  • full transform, shunt or series element first
  • shunt resonators with capacitive or inductive coupling
  • series resonators with shunt-C coupling
  • tubular, with optional end coils for a wider resonator range
  • Tumbular: the tubular with every L and C swapped, for a steeper lower skirt
  • coaxial (TEM line) resonators with capacitive coupling
  • quasi-symmetric (Carassa) for 10–50 % bandwidths
  • zig-zag elliptic with the fewest inductors (Saal–Ulbrich, direct bandpass synthesis)
• Exact band edges for coupled-resonator filters

Diplexers

• Lowpass/highpass diplexers from singly terminated channels (Butterworth, Chebyshev or elliptic), series L and series C at the common port
• S11, S21, S31, S22, S33 and isolation plotted

Practical design

• Live order estimate: the order each approximation needs for a given attenuation at a given frequency
• Standard component values (E24 / E48 / E96) with automatic snap-and-retune
• Inductor and capacitor Q in the simulation
• Export: Touchstone S2P / S3P, SPICE netlist, element list

Install (Windows)

• VektorFIL-1.0.0-setup.exe: installs for the current user, no admin rights needed. Adds VektorFIL and the user guide to the Start menu.
• VektorFIL-1.0.0-windows.zip: portable; unzip anywhere and run VektorFIL.exe.

No Python needed. Windows may show a SmartScreen warning because the program is not code-signed: click More info → Run anyway.

Other platforms: run from source (Python 3.10+), see the README.

Documentation

User guide with theory: https://ibelinp.github.io/vektorfil/

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Created from scratch by Pieter Ibelings with the help of Claude (Anthropic), written from published filter-synthesis theory. Free software under the GNU GPL v3. Provided as-is; issues and pull requests are not accepted.