Miniaturized Terminal Antennas Based On Electromagnetic Materials

With the rapid development of the modern mobile communication technologies,mobile terminal devices has been miniaturized than before.Some remarkable letters based on techniques,such as the coupled feeding network,loading bend line,loading lumped element and loading shorted stab,have been reported in the field in recent years.All of these techniques can reduce the size of the antenna effectively.Meanwhile,antennas based on metamaterials has been widely used in recent years,but only a few of them can be used for mobile terminal systems.The composite right/left-handed(CRLH)transmission line can constitute CRLH zero-order resonance,dual zero-order resonance,and multi-order resonances.The resonant frequency of the zero-order resonance of the metamaterial is only determined by the value of the capacitor and the inductor instead of the physical size of the structure.This means that when the antenna has been designed the size of the antenna can be more flexible.Thus,the minimal size of the antenna is determined by the size of the capacitor and inductor.This technique provides a theoretical basis for reducing the size of the terminal antenna.The content of this thesis is divided into the following parts.1.Miniaturized hepta-band mobile phone antenna design.A hepta-band miniaturized smart phone antenna based on zero-order resonant structure is designed.The proposed antenna covers the GSM850/900,GSM1800/1900,UMTS,LTE2300/2500 mobile communication bands.T-shaped monopole has been used to feed two CRLH-TL units in this design.The miniaturized design is realized while the operating band of the proposed antenna can be adjusted flexibly in the low-frequency band.To analyze and verify the designed antenna,it is fabricated and measured.Finally,the simulated and measured results of the antenna are agreed well with each other,and the proposed antenna can be applied in practice.2.Miniaturized 5G massive MIMO mobile phone antenna system design.Firstly,an antenna unit based on CRLH interdigital structure is designed.The structure of the unit cell of the antenna can suppress the effect of ground current effectively so that it has self-decoupling effect,and the unit cell of the proposed antenna has good radiation characteristics.Then,the antenna unit cell is used to form a 30-unit MIMO antenna system.The gap between adjacent unit cells is only 3.25 mm and it also satisfies the requirement of isolation of 5G mobile antennas.The 5G massive MIMO antenna has good radiation characteristics within the operating band from 4.8 GHz to 5.0 GHz.The antenna is fabricated and measured,and the measured results are consistent with the simulated results.3.Miniaturized printed wideband USB dongle antenna design.A compact wideband USB dongle antenna is designed.The antenna covers the LTE700,GSM850/900,GSM1800/1900,UMTS,LTE2300/2500.The antenna adopts an equivalent first-order series resonant circuit design to cover the low operating band,and uses two grounded parasitic branches to realize two resonant modes which covers high operating band.The antenna with a coupling feed,a load lumped element and a grounded parasitic miniaturization technique achieves a relatively compact structure.The antenna is fabricated,and the simulated and measured results of the antenna coincide with each other well.