Impedances: measurements and calculations for non-symmetric structures

Coupling impedances are most often calculated for beam enclosures of circular cross-section,and resulting formulae are used to interpret beam measurements, sometimes even in the case of .at chambers. This leads to misunderstand- ing and inaccurate evaluations.igourous analytic formulae exist for smooth,resistive chambers of elliptical or rectangular cross-section, while computer programs allow one to evaluate more complicated,non circular-symmetric geometries.At low frequencies the impedance of thin resistive walls departs from classical formulae.