Small-Size IFA Frame Antenna for the LTE Metal-Casing Smartphone

• Main Authors: Yu-Ching Wu, 吳昱慶
• Other Authors: Kin-Lu Wong
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/11678657889956025758

碩士 === 國立中山大學 === 電機工程學系研究所 === 104 === Two small-size frame antennas for the LTE metal-casing smartphone are presented. Both antennas are based on the inverted-F antenna (IFA) structure. The first antenna uses a frame section of 53 mm (about 0.16 wavelength at 900 MHz) along the short edge of the metal casing as the IFA’s radiating strip. By adding the matching circuit to the IFA structure, the antenna can provide a dual-wideband LTE operation to cover the low band of 824~960 MHz and high band of 1710~2690 MHz. The second antenna follows the design rule of the first antenna and achieves a simplified structure. A fundamental mode and two higher-order modes of the IFA’s radiating strip can be generated for the second antenna. By adding the wideband matching circuit in the feeding strip of the antenna, additional resonances in the low and middle bands are created to widen the bandwidths thereof. At the same time, a resonant mode in the high band can be generated by a parasitic shorted monopole, which is also formed by a small frame section along the short edge of the metal casing. With three resonant modes generated and a metal clearance of 2 mm only, the antenna can provide a triple-wideband LTE operation to cover the 824~960/1710~2690/3400~3800 MHz bands. Moreover, by selecting different inductances of the inductor at the shorting strip of the IFA, the resonant mode of the antenna’s low band can be shifted, so that the low band of 704~960 MHz can be covered. For the MIMO study, two second antennas are applied for the 2 × 2 MIMO operation. Good envelope correlation coefficients (ECCs) of the two antennas can be obtained, and much higher channel capacities can be achieved.