Contactless Varactor-Loaded Bandwidth-Enhanced Frequency-Reconfigurable Patch Antenna

A contactless varactor-loaded bandwidth-enhanced frequency-reconfigurable (FR) antenna (FRA) is proposed. On account of the different E-field distributions of the TM10 and TM30 modes, six shorting pins are introduced in the voltage zero of the E-field of the TM30 mode to push up the TM10 mode, which helps degenerate two modes to broaden the bandwidth. After that, a pair of frequency tuning lines with varactors attached to one end is partially inserted under the patch in a novel way to continuously tune the two modes simultaneously. The novel varactor-loading scheme obtains a trade-off between a high efficiency of larger than 50% and the frequency tuning range of 22.2% (2.04-2.55 GHz). The measured bandwidth exceeds 7.5%, exhibiting a bandwidth enhancement characteristic, and the peak gain varies between 6 and 7.9 dBi over the entire band.