The name field kinda feels like it could've been autogenerated from type and name or not contain the manufacturer and have it programmatically added at the page generation (or some later) stage.

This is a nitpick: in order to make YAML file edition easier it'd be nice to have a single entry in the file heavily commented with things like units and so on. For me it was kinda confusing whether I should be converting attenuation to dB/m or something else.

Data Coaxialcable.pdf
Pozdrawiam
Zbyszek SP3RNY

This is a nitpick.
I know that in the resulting page there is a link to Github but it wasn't obvious for me when I was looking for it. It'd be nice to add it under the <a>github.com/olgierd/coaxcalculator</a> or something similar.

5D-FB-Hansen:
name: 5D-FB
manufacturer: HANSEN
type: 5D-FB
attenuation: {100:6.3, 150:7.8, 280:10.8, 350:12.1, 400:13.0, 800:18.9, 900: +20.2, 1200:23.7, 1500:26.8, 1800:29.7, 1900:30.6, 2000:31.5, 2200:33.3, 2500: +35.8}
data_source: https://www.caledonian-cables.co.uk/Coaxia_Cable/50Ohm%20RF/5D- +FB.html
additional_info:
ext_diametr_mm: 7.5
velocity_factor: 0.82
impedance: 50

Small thing - selecting cable name (just cable name) with mouse - to be able to "copy" it (and then paste somewhere else) is impossible.

Here (google chrome 124.0.6367.119) it gets unselected automatically after releasing left mouse button.

Would be nice to be able to easily copy & paste names to google for their prices, availability etc.