Helical resonator filters with improved multipactor performance exploiting rigorous modelling and the large gap approach - Salza - 2019 - IET Microwaves, Antennas & Propagation - Wiley Online Library
145 MHz Low Loss Bandpass Helical Filter by Mile Kokotov - YouTube
Sturdy enclosure for helical filters etc : r/amateurradio
Filters for RadioJove
TMX249D Toko Helical Filter | eBay
Building a 145 MHz Low Loss Helical Bandpass Filter