Penetration Through Slots in Cylindrical Cavities Operating at Fundamental Cavity Modes

Penetration Through Slots in Cylindrical Cavities Operating at Fundamental Cavity Modes in the Presence of Electromagnetic Absorbers

“…Note that because we consider a cavity loaded with an absorber material here, the term Q total m,p,n appears in Eq. 2rather than the quality factor of a mode supported by an empty cavity Q cavity m,p,n as reported in [8]. This is not a trivial change that requires to be validated via experiments, as we do in this paper.…”

“…1 supports transverse magnetic (TM) and transverse electric (TE) modes [6,8,11,12]. We focus on TM modes here, and briefly summarize the analytical, unmatched formulation to calculate the shielding effectiveness versus frequency around cavity modes reported in [8], and modify it to allow for the modeling of cavities loaded with absorber materials. We focus on slot apertures operating below their resonant frequency; the case of slots operating at or above their resonant frequency will be considered in future work.…”

“…We focus on slot apertures operating below their resonant frequency; the case of slots operating at or above their resonant frequency will be considered in future work. Under time dependence exp(−iωt), for empty, fully-enclosed cylindrical cavities with internal height h and internal radius a, following [6,8,11,12], the interior magnetic resonant fields for fundamental TM modes even in z with indices (m, p, n) in space for 0 < φ < 2π, 0 < ρ < a, −h/2 < z < h/2 are…”

“…This protection is generally provided through electromagnetic shielding and may take the form of an enclosure, such as a metallic cavity, which may allow external EM fields to penetrate the interior of the cavity. This enclosure may support resonances with high-quality factor, which may lead to very large interior field levels [1][2][3][4][5][6][7][8]. These large fields could in turn be harmful to circuits and systems therein.…”

“…In this paper, we aim to model analytically EM absorbing material placement within a slotted cylindrical cavity to dampen the internal fields. In particular, we aim to combine two analytical models we previously developed to provide shielding effectiveness versus frequency at resonant modes in the presence of microwave absorber materials: 1) an unmatched formulation to model shielding effectiveness versus frequency [8]; and 2) a perturbation model approach to estimate the quality factor of cavities in the presence of absorbers [7]. It is important to point out that the first model provides shielding effectiveness spectra only for an empty cavity, while the second model only provides the quality factor change when an absorber is introduced within the cavity (and no shielding effectiveness spectra).…”