Flat delay network (butterworth)

Hard to say without any data. Like how many nsec per tap, maximally flat to which frequency etc.

Anyhow, you can buy delay lines (Belfuse and others).

In message , dated Sat, 9 Sep 2006, cali_eng writes

Yes; the realization may be anywhere from moderately difficult to marginally less than impossible.

You must give more data. Much more data. No, MORE!!!

Frequency range, amount of delay required, range of input impedances would be a START, no more than that. But it would be a start.

For a maximally flat delay network, consider a thousand-foot spool of CAT6 cable; there are four wire pairs (i.e. 4 microseconds of delay), and it's pretty good broadband.

You need to feed it at the characteristic impedance (use amplifier and/or attenuators with 110 ohm differential output), and terminate it properly. And if you need to tap it in the middle, you gotta splice in either a high-impedance shunt sense amplifier, or a low-impedance (transformer-coupled?) series sense amplifier.

For longer delays, PAL TV sets use an acoustic wave device (looks like a slab of glass with piezoelectric microphones cemented on), and waves in a Slinky can take several seconds (per Slinky, that is).

There are commercial 'delay lines' but these are generally lumped-constant approximations, you won't like what the waveforms look like.