Reconfigurable dual-band patch antenna using varactor-loaded slot

This paper introduces a new approach to design a microstrip patch antenna with reconfigurable dual band operation. Dual-band is achieved by the placement of a lumped capacitor on a slotted patch antenna, and the two resonant frequencies and their ratio are function of the capacitance value. Consequently, tuning of both frequencies is allowed by choosing proper capacitor value. If a varactor with an appropriate biasing network is used instead, electronic tuning is attained by changing the applied DC voltage. To understand the dual resonance behavior of the proposed antenna, a transmission line (TL) model with the wheeler incremental volume concept is established and validated with full wave simulation. The antenna shows 1.35-1.73 tunable frequency ratio with 0.5-1.1 pF capacitance. Moreover, the radiation patterns are similar at both bands.