Frequency-Reconfigurable Dielectric Patch Antenna With Bandwidth Enhancement

A frequency-reconfigurable bandwidth-enhanced dielectric patch antenna is investigated in this article. The modified feeding structure and air tunnel are introduced to incorporate the TM
₁₀
mode and antiphase TM
₂₀
mode, thereby expanding the antenna bandwidth. Meanwhile, the air tunnel provides space for the placement of frequency tuning components. After that, according to the
$E$
-field distribution of the modes, two pairs of varactor-loaded microstrip lines are implanted in the air tunnel and sides of the DP resonator to independently tune the TM
₁₀
mode and antiphase TM
₂₀
mode, respectively. Finally, the approximate synchronous tuning of two modes is realized through the appropriate parameter combination of the frequency tuning structure. During the tuning process of the operating frequency, the bandwidth enhancement characteristic of the resultant antenna is obtained while maintaining high gain, good efficiency, and low profile (
$0.06\lambda _{0})$
. The fractional bandwidth of each state varies from 7.9% to 13.1%. The −10 dB frequency coverage of the antenna is 22.6% (4.28–5.37 GHz). As the operating frequency shifts down, the peak gain varies from 8 to 6.2 dBi while the peak efficiency changes from 93% to 82%.