In this work, a new design of small microstrip antenna with variable band-notched filtering characteristic for super ultra-wideband (UWB) applications including 5G/IoT networks is presented. In the proposed structure by creating steps with optimized appropriate sizes and angles in the lower edges of the quasi-square patch antenna and by a new technique of modifying the ground plane, more efficient radiation patterns and characteristic impedance are achieved. Moreover, the omnidirectional low cross-polarized H-plane radiation patterns are obtained in frequency band of 3-11 GHz. Also, its radiation patterns are improved between 11 and 14.5 GHz and have better performance especially with tuning capacitors between 14.5 and 20 GHz. In addition, its frequency bandwidth with VSWR < 2 is from 3 GHz to 50 GHz which covers 5G networks and both ultra-wideband (UWB) and super wideband (SWB) communications. A rectangular slot on the patch is used to create an integrated band-notch filter in the structure to avoid interference with other wireless systems like wireless local area networks (WLANs), and this specification can be activated or deactivated by a PIN diode. In addition, the center frequency of the filter can be tuned by just a varactor diode or a variable capacitor and/or by changing the position of the capacitors in frequency range of about 3.5-6 GHz, which rejects interference of all WLANs and even their lower and upper bands, and nulls in the radiation patterns can be changed especially in upper bands as well. The final structure simulation results are in good agreement with measurement ones.

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