Tham khảo tài liệu 'advances in satellite communications part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Passive Microwave Feed Chains for High Capacity Satellite Communications Systems 139 parallel-plate waveguide. It is worth mentioning that since the EM field inside a generic component can deviate significantly from the TEM field in a plane parallel-plate waveguide the rigorous analysis of the multipaction breakdown would require extensive numerical computations of the electronic trajectories inside the devices in order to establish if an avalanche of secondary-emission electrons can occur Anza et al. 2008 - Tienda et al 2006 . Fig. . Envelope over all the resonance order of the minimum multipactor threshold voltage V0 as a function of the gap-frequency product fd for a silver-plated parallel-plate waveguide. Fig. . Transmission coefficient T21 f of the E-plane WR75-waveguide symmetric stubfilter shown in the insert the inside waveguide structure of the filter is reported . However according to the ESA recommendations the qualification process of a generic RF component in terms of the power-handling under both single- and multi-carrier operating 140 Advances in Satellite Communications conditions can be carried out by evaluating an upper-bound on the multipaction risk and setting appropriate confidence margins. In particular the actual upper-bound is computed by using the plane parallel-plate model along several directions inside the component. For sake of clarity and without loss of generality this procedure is described next by referring to the E-plane WR75-waveguide symmetric stub-filter depicted in the insert of Fig. where the transmission coefficient T21 f of this filter is reported. The transmission coefficient is the relevant characteristic function of the filter since it is equal to the ratio S11 f S21 f where S11 f is the scattering reflection coefficient at the input port and S21 f is the scattering transmission coefficient from one port to the other. Hence the transmission coefficient T21 f is proportional to the reflection coefficient in the .