Small Flexible Antenna Design

Flexible circuits,sensors,chips have potentials in wearable devices,implantable devices,soft robots,and satellite equipments.An antenna is an important component of wireless communication system.A flexible antenna printed on flexible substrate is easier to integrate with other flexible electronic devices and has virtues of low profile,light weight,good flexibility,and easy folding.Due to very thin thickness of substrate,there are challenges in flexible antenna design,such as bandwidth enhancement,gain improvement,direction radiation.In this thesis,three types of novel flexible antennas have been proposed which can be applied in small ultrawide band(UWB)remianls,satellite network system,and5G terminals.(1)A coplanar waveguide fed UWB antenna has been proposed applied in small UWB terminals.The antenna substrate is polymide(PI)with 0.02 mm thickness.A hybrid shaped slot consisted with a rectangle and a circle is etched on the ground plane to obtain antenna miniaturization.The total size of the proposed UWB antenna is 32×25mm~2.The measured bandwidth of the prosed antenna covers 2.41-10.66GHz.Compared with published antenna the proposed antenna has smaller size and wider bandwidth.(2)Microstrip antenna arrays have been proposed applied in satellite newtwork terminal working at 12 GHz.The antenna element is of a microstrip antenna with square shaped patch.Two arrays with 2×3 elements and 2×5 elements have been proposed separately by series and parallel combined feeding.The antenna substrate is PI with 0.06 mm thickness.The total size of the 2×3 array is 41.3×16.2 mm~2and the measured bandwidth is11.84-12.48GHz.The total size of the 2×5 array is 64×16.2 mm~2and the measured bandwidth is 11.73-12.56GHz.The two antennas have directional radiation patterns.In this thesis,the directional radiation characteristics of antenna array have been analyzed.For 1×n array,the antenna has directional pattern at the nth resonance.For 2×n array,the antenna has directional pattern at the 2×nth resonance.(3)An antenna array have been proposed for 5G communication terminal working at24 GHz.The antenna element is of a microstrip antenna with square shaped patch.The antenna array consists of eight elements series connected with ring shape.A one-two power divider is adopted to feeding the array.The antenna substrate is PI with 0.06 mm thickness.The antenna array is designed working at 12GHz.Then scale-model technique is adopted to tune the antenna frequency to 24 GHz with half reduce the antenna size and optimization antenna dimension.The total size of antenna array is 25×28 mm~2and the measured bandwidth is 23.7-24.6GHz.Compared with published flexible antennas,the proposed antenna has virtues of thinner substrate.