2P · rfsynth Microwave synthesis

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Microstrip synthesis

Hairpin bandpass filter

Edge-coupled resonators folded into hairpins.

unconfirmed  Closed form not yet confirmed against full-wave EM The hairpin fold is modelled as an equivalent edge-coupled section. That approximation is plausible and widely used, but 2P's own EM cross-check for it is still open, so the predicted response has not been confirmed against a full-wave solve. Expect the centre frequency to be close and the band edges to move.

Specification

The band edges of the passband. Centre frequency is their geometric mean, not their average.
0.1 – 40 GHz.
0.10 means a 10 % passband. Above about 0.2 the coupled-line gaps get very tight, and the fab check will tell you.

= 4.7 GHz centre, 10 % bandwidth

Number of resonators. Higher is steeper and lossier.
Chebyshev only. 0.1 dB is a common choice for a clean passband; 0.5 dB buys steeper skirts.
Permittivities are datasheet design values, transcribed by hand. Check them against the current datasheet before you commit copper.

What reaches the engine

Type over any of these and the laminate becomes custom. tan δ does not reach the response, which is lossless; it decides whether this page warns you about a lossy laminate. εr, h and copper thickness all reach the microstrip solution. 1 oz copper is 0.035 mm.

What you get

Enter a specification and press Synthesise. Every result includes:

  • Physical dimensions: widths, gaps and lengths in millimetres
  • A drawn layout, to scale
  • The predicted response, with the honesty label above attached to it
  • A manufacturability check against six real process envelopes: Lintek in Australia, PCBWay and JLCPCB
  • The models used and the range over which they are valid
  • A KiCad footprint and a DXF you can take straight to CAD
  • A parametric CST macro, on the three bandpass filters

Nothing is stored against you, and the result page has a shareable address.