[nestes]

The 600-6GHz range is a rough approximation for some of the most used bands in telecommunications, e.g. Wi-Fi and 5G NR FR1. It's worth noting that the article explicitly mentions that this filter will be useful for FR3, which is "7 GHz to 24 GHz". They do not claim full 600 MHz-6 GHz operation, and as the previous poster noted, the filter was demonstrated from 3.4-11.1 GHz.

More critically: you want to be very very careful about trying to extrapolate this filter down to lower frequencies. We're dealing with "weird physics" here. I am not an expert on spin-wave devices by any means, but a guy in my lab during grad school was working with them, so I do know that the resonant frequencies of the spin-waves are a function of the magnetic bias and the material. The researchers here are tuning the filter by tuning the magnetic bias. Someone more knowledgeable can correct me, but I believe YIG would have trouble propagating spin-waves down at 600 MHz, and so this kind of filter would not be practical.