A Rectangular Patch Antenna With Wideband Harmonic Suppression

In this letter, a new design scheme for rectangular patch antenna with harmonic suppression is proposed and analyzed. First, field distributions of the resonant modes on rectangular patch are calculated and used to provide theoretical guidance for arranging feeding strategy. Subsequently, by reasonably placing two pairs of differential exciting signals at the virtual electrical wall of partial high-order modes on the rectangular patch antenna, harmonic suppression can be initially obtained. Moreover, to implement this equal amplitude and out-of-phase signals, a 1-to-4 power divider based on microstrip to slotline transitions is conceived and realized. Finally, a prototype antenna is fabricated and tested to prove the feasibility of the theoretical predictions. Measured results reveal the demonstrator realizes an impedance bandwidth of 8.6% (3.12-3.4 GHz). Most importantly, compared with the traditional filtering antenna, the suppression of harmonics around 3.4f(0) (f(0) is the center frequency of the antenna) is successfully acquired.