Bandwidth Enhancement of Small Square Monopole Antenna Using Self-Complementary Structure for Microwave Imaging System Applications
Keywords:
Babinet’s equivalence principle, microwave imaging system, self-complementary structure, square monopole antennaAbstract
A novel printed monopole antenna for ultrawideband (UWB) applications is designed based on self-complementary structure as a matching network. The proposed antenna consists of a square radiating patch and a self-complementary structure located next to feed line, which provides a wide usable fractional bandwidth of more than 100% (3.04-11.43 GHz). Selfcomplementary matching network is created, by cutting two rectangular ring slots on the ground plane and by inserting two rectangular rings coupled elements in the top layer; hence, additional resonances are excited and much wider impedance bandwidth can be produced. The designed antenna has a small size of 14×22 mm2 , about 0.15?×0.25? at 4.3 GHz. It is shown that simulated and measured results agree well with each other and demonstrate the usefulness of the proposed antenna for UWB applications. The proposed antenna exhibits almost omni-directional radiation patterns with low crosspolarization levels and provides an acceptable gain over whole band.
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References
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