Print a compact single- and quad-band slot antenna on ceramic substrate

A miniaturized slot antenna is designed on the 0.4mmthickness Al2O3 ceramic substrate with ground plane size of 30mm × 30mm and the printed method is used to get the designed patterns. Two different strip insets, U-shape and N-shape, are added in the slot to improve the characteristics of microstrip fed antennas. When a symmetrical U-shaped strip inset is added in the slot, the fabricated antenna reveals a single-band characteristic and has a relatively large return loss of −28.0 dB at 3.12GHz and a wide −10 dB impendence bandwidth of 8.9% (275 MHz). When an un-symmetrical N-shaped strip inset is added, the antenna reveals the quad-band characteristics with the resonant frequencies at 2.22 GHz, 3.23 GHz, 4.63 GHz, and 5.42 GHz, respectively. The gains and far-field radiation patterns of the N-shaped antenna are also developed in this study.