Multiple stubs loaded efficient electrically small antenna for DCS/WiMAX/5G NR-n77/n78 applications

This work presents an electrically small antenna (ESA) for wireless applications, such as digital cellular systems (DCS1800), WiMAX, and sub 6 GHz - 5G new radio (NR) systems. The proposed antenna offers a triple band resonance centered at 1.825, 3.3, and 3.58 GHz. Here, impedance matching networks of printed microstrip line sections, such as inverted 'L', open-ended line, meandered line, and capacitive stub, are used to achieve impedance matching at the desired frequencies. The total surface area of the proposed antenna is 0.14 lambda x 0.06 lambda, where lambda is the wavelength at 1.825 GHz. The designed antenna is tested for its impedance and radiation characteristics. The fabricated prototype offers fractional bandwidth (FBW, with VSWR < 2) of 1.6%, 6%, and 6.7% centered at 1.825, 3.3, and 3.58 GHz, respectively, whereas for VSWR 3:1, the achieved fraction bandwidth(s) is 8.2% and 24.5% for the DCS1800 and 3.3 GHz band, respectively. The stable and nearly omnidirectional radiation pattern for each operating frequency bands indicates the suitability of the proposed antenna for the intended application(s).