| With the rapid improvement of wireless mobile communication capability, the userof mobile phones explosively increases every year. Operators claim that phones shouldcover various communication systems and could download quickly so as to meet theusers’ demands roundly. MIMO technique working in wideband can exactly meet therequirement.Antenna researchers do large quantities of researches on the ultra wideband singleantenna design for mobile phones, and there are many useful methods for bandenhancement, but ultra wideband antenna design is still a big challenge. For example,when the single antenna is well designed, it is lack of relevant study that how todecrease the decoupling between the mobile phone antennas and enhance the portisolation. Moreover, those ways are just suitable for the narrow-band decoupling not thewideband. For this purpose, the thesis conducts relevant researches:1. It studies multiple potential antenna layouts respectively based on two differenttypes of ultra wideband single antenna. It discusses and compares the working band,port isolation and envelope of the cross correlation of every layout project, and concludethat antenna layout is an easy and efficient technical measures which can improve portisolation.2. It designs and fabricates a planar wideband double-antenna working at1710~27700MHz by itself with a100×50×0.8mm3PCB and each antenna occupies10×20mm2separately. The antenna unit is couple-fed, and combines the short circuitground technique. Under useful antenna layout, it can achieve20dB port isolationduring the working band, the envelope of cross correlation (ECC) is less than0.17andthe measured efficiency is higher than56.6%.3. It redesigns and re-optimizes a known ultra wideband antenna, using antennasupport and bending ground technique, and proposes an ultra wideband antenna designproject covering698~960、1710~2700MHz, which the whole chassis, PCB, andantenna occupy105×58×13、100×52×0.8、15×31×5mm3respectively. Then, it choosesan antenna layout project, takes the redesigned ultra wideband antenna as the antenna unit, and designs an ultra-wideband double antenna project. In the whole frequencyrange, the isolation can achieve10dB, while the lower part can be achieved12dB; ECCis less than0.15and the efficiency is higher than62%.4. It discusses that why the antenna layout can reduce the decoupling byobserving the near-field total electric field distribution. This study shows that theantenna layout can change the magnitude of the electric field of the un-fed port. Less themagnitude of the electric field is, better the port isolation is. |
PDF Full Text Request