Method for limiting spurious resonant cavity effects in electronic

Abstract

Spurious cavity resonance effects in a cabinet housing electronics circuitry are suppressed by determining the maximum repetition rate or frequency for legitimate signals which can appear in the circuitry and then establishing the dimensions of each cavity within the cabinet such that each cavity's resonant frequency is higher than the critical repetition rate/frequency. Since a given cavity in a cabinet is typically block-shaped (such as the space between a cabinet door and the circuit panel facing the door), a special purpose formula may be employed to obtain a good approximation of the cavity's resonant frequency, and the cavity dimensions then adjusted to raise the cavity resonant frequency above the critical frequency. For the still more particular cavity configuration in which the length is greater than the width which is much greater than the depth, a further simplified formula can be employed to find an approximate cavity resonant frequency. In addition, for the common configuration in which one or more significant intrusions reduce the cavity volume, a more complex formula may be employed to find its approximate resonant frequency with the cavity dimensions then being adjusted to raise that approximate resonant frequency above the critical frequency. The method may be employed either in the design stage or at a remedial stage.