Bandwidth-Enhanced Frequency-Agile Stacked Patch Antenna Sharing Common Tuning Element

A bandwidth-enhanced frequency-agile stacked patch antenna sharing a common tuning element is proposed. Benefiting from the stacked patch structure, the proposed antenna obtains enhanced bandwidth and significantly reduces the antenna size. Based on the strongest E-fields on both edges, which are perpendicular to the polarized direction, a pair of microstrip lines is embedded between the edges of the two patches. Besides, the application of two varactors implanted in the microstrip lines enables the proposed antenna to synchronously tune the two resonant frequencies. The shared tuning element makes the proposed antenna to obtain a stable enhanced bandwidth of about 15% over the entire frequency tuning range of 33.4% [(1.87 to 2.62) GHz]. The gain and peak efficiency vary from 3 dBi to 5.5 dBi and 76% to 88% over the entire band, respectively. The remarkable performances of the proposed antenna make it suitable for low-cost Internet of Things (IoT) devices.