Fitting a shunt capacitor to a real FSS is done by repeated running of a first principles code to match the reflection response of the shunt capacitor with the reflection from a capacitive FSS . Patch-type FSS below resonance will produce a capacitive shunt admittance equivalent circuit, with closer packing of elements in the FSS sheet yielding higher shunt capacitance values in the equivalent circuit.
22.
The thickness of the air spacers may be determined as shown in Fig . 3.1 . 3-1, in which we compare the ABCD matrix of a series inductor with the ABCD matrix of a short transmission line ( Ramo [ 1994 ] ), in order to obtain the proper length of transmission line between the shunt capacitors ( sub-resonant FSS layers ) to produce a Butterworth filter response.
