Equivalent circuits for an electrically thick square patch directly fed by a coaxial probe or by a microstrip line

The authors present lumped-element equivalent circuits for two specific square patches on an electrically thick (0.05 lambda /sub 0/) substrate. The equivalent circuits were derived from experimental data and could be useful in the verification of theoretical techniques. For the particular geometry studied the probe fed patch requires sidelengths approximately 6% shorter than the microstrip fed patch, for the same resonant frequency. The microstrip-fed patch has a sharper resonance and approximately half the bandwidth of the probe-fed patch. Presumably the probe introduces more losses than the microstrip, thus damping the patch resonance. >