Modes of resonance of the Jerusalem cross in frequency-selective surfaces

Two frequency-selective surfaces consisting of arrays of Jerusalem crosses have been analysed using a modal technique. Calculated plane-wave-transmission coefficients are compared with experimental values in the frequency range 1¿40 GHz, for incidence up to 50° in the principal planes. At each reflection resonance the calculated element current distribution is illustrated and discussed. At the main resonance the current is confined largely to the E-plane arm of the cross, whereas, at higher frequencies, asymmetrical resonances of the entire structure are observed. 22 basis functions are required to represent the element current over the entire frequency range, but computer processing time can be reduced by identifying the significant functions in restricted wavebands.