The Research And Design Of Compact Multi–Band And Broadband Microstrip Antenna

Antenna is a key of wireless communication system,via which the electromagnetic energy radiates out.The radiation performance of antenna directly affects the quality of communication.Microstrip antenna is in the growing applications in various wireless electronic devices with advantages of good coplanarity,simple structure,easy integration,etc.In this paper,the multi-band design and spectrum extension technology of miniaturized microstrip antennas are studied and several antennas are designed.The main contents of this thesis are as follows:(1)Two novel tri-band antennas are designed.The folded monopole is used in the first antenna to reduce the size of the antenna,which works in WLAN and WiMAX frequency bands through the ground plate to load the gap.The second antenna is a tri-band rectangle microstrip antenna fed by the coaxial line.The single-chip method of measures of fulfilling multi-band antenna is adopted.The appropriate feed point is selected in a single radiation patch to excite the two resonant frequencies,which are 4G mobile communication bands.Besides,the slit design on the radiation patch can stimulate the higher frequency which is in the future 5G communication frequency band.(2)The band broadening technologies are summarized and three new broadband antennas are designed by using band expansion methods.The wide-band design of the antenna is realized by reducing the antenna quality factor and the multi-resonance method.The impedance bandwidth is extended from the original basis to the entire civil ultra-wideband band by loading ground with the defective structure.Two broadband antennas are designed fed by the coplanar waveguide.One is cloud-like broadband antenna covering the WIFI2.45 GHz,WiMAX2.6GHz,WiMAX3.5GHz band and another is umbrella-like antenna which can be applied in the whole Netcom mobile phone.