Summary
Energy accumulation effects near the open end of a parallel-plate waveguide, due to the diffraction of an incident pulse travelling within the waveguide, are investigated. The behaviour of the reflected pulse at large distances from the open end provides information about the times taken for the formation and depletion of the energy reservoir near the edges. The effects of low-frequency and of high-frequency components are separately discussed. The low-frequency components are related with the retardation and width of the reflected pulse, whereas the high-frequency components determine its behaviour in the immediate neighbourhood of the wave front. The asymptotic behaviour of the reflection coefficient of the principal mode at high frequencies is derived. The effect of higher-order modes is briefly discussed.
Riassunto
Si studiano gli effetti dell’accumulazione dell’energia presso l’estremità aperta di una guida d’onda a piastre parallele, dovuta alla diffrazione di un impulso incidente che corre entro la guida d’onda. Il comportamento dell’impulso riflesso a grandi distanze dall’estremità aperta fornisce informazioni sul tempo impiegato per la formazione e lo svuotamento del serbatoio d’energia presso i bordi. Si discutono separatamente gli effetti delle componenti a bassa e ad alta frequenza. Le componenti a bassa frequenza sono in rapporto con il ritardo e l’ampiezza dell’impulso riflesso, mentre le componenti ad alta frequenza definiscono il suo comportamento nelle vicinanze immediate del fronte d’onda. Si deduce il comportamento asintotico del coefficiente di riflessione del modo principale alle alte frequenze. Si discute brevemente l’effetto dei modi di ordine più elevato.
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da Costa, R.C.T. On the diffraction of a pulse at the open end of a parallel-plate waveguide. Nuovo Cim 25, 55–68 (1962). https://doi.org/10.1007/BF02733316
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DOI: https://doi.org/10.1007/BF02733316