The Ryder paper (here) uses a tuned front end. The specified coils (Toko E526HN-100319) seem to be unobtainable, but surprisingly, E526HN-100119 are available (just about), and it looks like they are very similar (I don’t know what the difference is). Of course, any inductor could be used of the correct value, but these particular ones have a very high Q which is desirable for the front end. Coilcraft had some with a Q approaching similar values, so those could be used when the Toko ones are no longer available. The image below is of the E526HN-100119.