In this study, the principle of band suppressing an UWB antenna by attaching a small resonator is explained by developing its\nequivalent circuit.The realized UWB antenna is a conical monopole antenna that contains a split loop for band suppression. The\nconicalmonopole antenna corresponds to a transmission line terminated with load impedance, and the split loop is an LCresonator.\nThe coupling between the conicalmonopole antenna and the split loop is represented asmutual inductance. Equivalent circuits for\nthe UWB antenna suppressing single band [WLAN] and dual band [WLAN,WiMAX] have been suggested, and these equivalent\ncircuits provide insight into the performance characteristics of the developed band suppressed UWB antenna to which a small\nsized resonator is installed. Simulation and measurement results on the input impedance and VSWR of the proposed equivalent\ncircuit are closely matched.Thus, the validity of the equivalent circuit is confirmed. The measurement results demonstrate that the\nproposed antenna exhibits a gain of over 3 dBi in the working band and has an omnidirectional radiation pattern. Band rejection\nhas been also implemented by split loops.
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