Multiband Printed Koch Antenna Unified with Hilbert Split-Ring Structure for Better Front-to-Back Ratio

Abstract

A multiband printed Koch antenna integrated with multi-band high-impedance surface (HIS) is proposed. The antenna can operate at three frequencies like 11.725 GHz, 26.155 GHz and 39.22 GHz which covers application in frequency bands namely X-band (8-12 GHz), K-band (18-27 GHz), and Ka-band (26.5-40 GHz). In order to achieve a modest design with better front-to-back ratio (FBR), gain, directivity and radiation efficiency a multi-band Hilbert split-ring HIS is presented as a reflector. The proposed HIS has an array of slotted square patches based on Hilbert curve. This arrangement provides in-phase reflection at the operating frequencies and can be presented as an artificial magnetic conductor (AMC). The antenna when integrated with HIS has an incorporated uniform profile thickness of 2 mm for different frequencies of operation. The printed Koch antenna is simulated, analyzed for various substrate thickness and is finally integrated with Hilbert split-ring HIS to obtain good FBR and radiation efficiency in all the three bands.