A Multiband Slot Antenna with the Fractal Narrow Slit fed by Capacitive Coupling

This paper presented a modifying fractal slit fed by capacitive coupling based on slot antenna for multiband operation. Two rectangular steps are added within a slot antenna. Also, the modified fractal slit is created by etching an inner rectangular stub fed by capacitive coupling. Then, the proposed antenna can be operated in multi band frequencies to support the wireless communication systems. The dimension of proposed antenna with this technique is smaller than conventional slot antenna about 23.6%. The |S11| levels of antenna are lower than -10 dB at the operating frequencies of 900 MHz, 1500 MHz, 1800 MHz, and 2.45 GHz, respectively. It can support the application of LoRa in IoT, GPS or GNSS system, 3G LTE 1800, and WiFi standard in IEEE 802.11 b/g at 2.45 GHz. The radiation patterns of the proposed antenna in every operating frequencies are bi-directional in XZ-planes and YZ-planes. Moreover, The antenna gain can achieved approximately 2.5 dBi.