Reduced size of slotted‐fractal Koch log‐periodic antenna for 802.11af TVWS application

A reduced size of log-periodic fractal Koch antenna (LPFKA) design with rectangular slots for Television White Space Spectrum (TVWS) bands application is proposed in this letter. The new introduced design technique of tilted rectangular slots into the fractal Koch radiating elements found out to enhance the impedance bandwidth as well as realizing high gain and reducing the size of log-periodic antenna. The 10 LPFKA's radiating elements are located on both sides of the substrate in a crisscross arrangement and obtained 15.3% miniaturization as well as 50.79% bandwidth and maximum of 36% gain increment. The proposed antenna has a largest dimension of 305 x 280 mm(2), that is 0.44 lambda x 0.48 lambda over the lowest operating frequency of the 0.47-0.79 GHz TVWS bands. This antenna exhibits high gains of between 4.41 and 7.2 dBi and stable radiation patterns throughout the required UHF TVWS bands. (C) 2015 Wiley Periodicals, Inc.