An I-Shaped Slot Grid Antenna Array with Substrate Integration and Enhanced Bandwidth

Aimed to transmit electromagnetic energy in wireless power transfer, a planar substrate-integrated grid antenna array with four I-shaped slots was designed. A transverse stub was added to the microstrip line to produce additional resonance; hence, the impedance bandwidth was enhanced from 1.9% to 6%. Four I-shaped slots were formed on a perfect electric conductor (PEC) sheet to realize boresight radiation. Four gaps were etched to refine and compress the in-band impedance property. Furthermore, characteristic mode theory was adopted to analyze the working mechanism. Finally, the measurement results showed that the antenna had an operating bandwidth of 5% (|S₁₁| < -10 dB from 5.67 GHz to 5.96 GHz). In the operating band, the boresight gain varied from 9.3 dBi to 11.3 dBi. The cross-polarization level was lower than -30 dB on the boresight. Therefore, the proposed array is suitable for use in wireless power transfer systems and other related applications.