Meaning
Radio frequency rejection defines the separation required between passband transmission and stopband attenuation when cavity bandpass filter isolation is evaluated during final assembly qualification. The parameter quantifies signal attenuation levels between adjacent resonator poles to prevent interchannel interference inside dense transceiver arrays. Acceptance criteria appear in the factory test report accompanying each shipped subsystem, validating that unwanted spectral energy remains below specified thresholds before integration into larger communication architectures.
Thermal Drift
Metal expansion alters physical dimensions inside resonant chambers when operating temperatures rise during continuous transmission cycles. Resonant frequency shifts force passband edges to migrate toward neighboring channels, directly degrading stopband attenuation performance. Nickel plated invar construction minimizes mechanical displacement, holding insertion loss stability across the rated thermal operating envelope.
Housing Leakage
Seam gaps permit stray electromagnetic fields to bypass internal tuning screws, introducing parasitic coupling paths that degrade ultimate stopband rejection. Silver filled gaskets and continuous laser welds seal mating surfaces against high frequency radiation leakage during environmental stress screening. Assembly technicians verify housing integrity using near field probes before sealing the enclosure for final customer acceptance.
Impedance Mismatch
Voltage standing wave ratio spikes reflect unwanted power back toward active transceiver components, destabilizing upstream power amplifier stages. Phase cancellation inside coaxial connectors creates localized field distortions, reducing effective stopband rejection margins under mismatched load conditions. Proper tuning screw adjustment restores input match, ensuring insertion losses stay within acceptable system integration limits.
