Miniaturized Log Periodic Fractal Koch Antenna with C-Shaped Stub

Abstract

A reduced size of Log Periodic Fractal Koch Antenna (LPFKA) with C-shaped stub is proposed in this paper mainly for Television White Space Spectrum (TVWS) applications which operate from 0.47 GHz to 0.79 GHz. The proposed antenna has a dimension of 285 mm x 220 mm which planned on FR-4 substrate with dielectric constant of εr = 4.7, loss tangent of tan δ = 0.019 and thickness of 1.6 mm. The addition of C-shaped stub at each end of the fractal Koch radiating element manages to reduce the dimension of conventional antenna by 26.58%. Log periodic antenna with C-shaped stub technique is able to achieve higher impedance bandwidth with the increase of the resonant length without additional space. The results show a good agreement with stable radiation patterns across the operating bands. With the gains varies from 4.35 dBi to 6.69 dBi and reflection coefficient below than -10 dB over the desired frequencies range, this antenna has a big potential for TVWS applications.