On-board miniaturized L-band input filter based On TM-mode dielectric resonator for MSS applications

This paper presents a very compact L-band input filter based on TM010 mode dielectric resonators for MSS (Mobile Satellite Service) applications. A dielectric resonator (relative permittivity of 78) operating with TM010 mode represents the best trade-off in terms of volume occupation and resonator unloaded Q-factor among several dielectric resonator types considered for the proposed application. Non-resonating modes of the TM dielectric cavity have been adopted in the filter design to generate transmission zeros able to improve the rejection of the 2
^nd
order filter when required. Prototypes of an L-band 2
^nd
order bandpass filter have been manufactured and tested. A stable RF response between −30°C and +70°C has been demonstrated by a proprietary technique used to ensure the thermal stability of the filter. The achieved volume saving is 50% with respect to the reference standard technology.