| Summary: | 碩士 === 逢甲大學 === 通訊工程學系 === 107 === This thesis focuses on multi-band antennas in mobile handset for 4G and 5G communication system applications. All of proposed three designs are applied to smartphones. The main structure of designed antennas includes monopole, slot, and loop antennas.
The first design is a multi-branch antenna which is applied to 4G smartphone and can cover the LTE 700/2300/2500 (698~787 MHz, 2300~2400 MHz, 2500~2690 MHz), GSM 850/900/1800/1900 (824~894 MHz, 890~960 MHz, 1710~1880 MHz, 1850~1990 MHz), UMTS 2100 (1920~2170 MHz) bands. A multi-branch monopole is designed for principal structure which can excite the mainly resonant mode. A grounding strip is added to broaden the lower bandwidth. The design doesn’t need any lumped elements and has a size of 70 mm×6 mm×6 mm. It is only with 6 mm small non-ground portion and suitable for modern large screen smartphone applications.
Then, the second design is a multiple antenna array proposed for future 5G smartphone. The antenna array consists of three kinds of antenna design. Overall operating frequency bands cover the WLAN 2.4/5.2/5.8 GHz (2400~2488 MHz, 5150~5350 MHz, 5725~5875 MHz) and Sub-6 GHz (3300~3600 MHz) bands. The two WLAN antennas are placed on the top and bottom corners of the board and are designed into three-dimensional architecture to reduce the area of antennas. The size of single antenna is 10 mm×7.2 mm×4.2 mm. The other MIMO antennas are operating at Sub-6 GHz bands and consist of eight antennas which are arranged on both metal-rimmed sides. Two types of open-slot antennas are selected for better isolation and size reduction. The antenna sizes are 6 mm×7.7 mm×2 mm and 6 mm×10.5 mm, respectively. This design is applicable to future 5G MIMO metal-rimmed smartphones.
Finally, the third design is also applied to future 5G smartphone. This design is especially suitable to the conditions of insufficient space between multiple antennas. The improved method is to design a coupled-fed loop antenna and connect it to another antenna with a co-connected shorting strip. This arrangement can greatly reduce the required area of the dual antennas. The key point of design is to let the grounding strip have band-pass characteristic and prevent the current flowing to another antenna. This design can improve the mutual coupling between two antennas. The total size of two antennas is 6 mm×26 mm, This antenna array is operating at Sub-6 GHz (3400~3600 MHz) band for future 5G MIMO smartphone applications.
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