Equivalent circuit modelling of a frequency selective plasterboard wall

The frequency response of a bandstop square-loop frequency selective (FS) structure illuminated at an oblique angle can be accurately predicted using a simple equivalent circuit model. A frequency selective plasterboard wall was constructed and measured to reveal a downwards change in resonant frequency (with at least 30 dB attenuation) from 9.2 GHz at an incident angle of 0° (normal) to 8.5 GHz at 45° incidence. The equivalent circuit model predictions align well with measurements. The model allows the rapid prediction of FS surface response and aids the design of FS structures that have desirable (less angle-dependent) characteristics.