Dual‐feed U‐slot antenna having low envelope correlation coefficients for the LTE MIMO operation in the metal‐framed smartphone

Abstract

A printed dual‐feed U‐shaped open‐slot (U‐slot) antenna disposed close to the top or bottom short edge of the system ground plane in the metal‐framed smartphone for the LTE (long‐term evolution) MIMO (multi‐input multi‐output) operation is presented. The U‐slot is printed in the ground region within 10 mm to the short edge of the system ground plane and its two open ends are disposed at the short edge thereof. The former makes the system ground plane capable of accommodating a large display panel for the smartphone, while the latter decreases the effects of the user's hand holding the smartphone. The U‐slot is short‐circuited at one position therein to provide one longer open slot and one shorter open slot, which are fed separately by two feed networks to form Ant1 and Ant2. Ant1 can cover the LTE low band (LB, 746–960 MHz for Band 13/5/8) and LTE middle/high band (M/HB, 1710–2690 MHz). Ant2 can cover the LTE M/HB in 1710–2690 MHz. In addition, very low envelope correlation coefficients (ECCs) less than 0.1 in the LTE M/HB for Ant1 and Ant2 can be obtained. That is, in addition to the coverage of the LTE LB, the dual‐feed U‐slot antenna can be applied for the 2 × 2 LTE M/HB MIMO operation. The antenna structure and operating principle of the dual‐feed U‐slot antenna are presented, and the antenna performance is verified by the experimental study.

Multiantennas conjoined with metal frame and integrated into 8 × 8 m ultiple‐input and m ultiple‐output array for fifth generation smartphone applications

“…At present, the mainstream mobile phone market primarily uses metal casings. With metal casings, the slot antenna 2‐5 is often used to solve the problem of metal shielding the antenna radiation mechanism, resulting in the appearance of an all‐metal back cover that causes discontinuities. The narrow design space and need to increase the efficiency of the spectrum necessitate implementing multiple bands and supporting a MIMO configuration.…”

One LTE LB and two conjoined LTE M/HB MIMO antennas with a compact symmetric frame structure at the short edge of the metal‐framed smartphone

“…The reported metal‐frame antennas that include at least two LTE antennas to provide two LTE L/M/HBs or one LTE LB and two LTE M/HBs for multi‐input multi‐output (MIMO) operation are relatively very few . In Ref.…”

“…For modern slim smartphones, the metal-frame structure around the edges of the smartphone has become very popular to achieve robustness thereof. 1,2 For such metal-framed smartphones, the long-term evolution (LTE) antennas integrated with the metal-frame structure to operate as loop antennas [3][4][5][6][7] or inverted-F antennas (IFAs) [8][9][10][11][12] or open-slot antennas 12,13 have also been reported. It is noted that many of the reported metal-frame LTE antennas can cover one LTE low band (LB) and one LTE middle/high band (M/HB) only.…”

“…3,[5][6][7][8][9][10] The reported metal-frame antennas that include at least two LTE antennas to provide two LTE L/M/HBs or one LTE LB and two LTE M/HBs for multi-input multi-output (MIMO) operation are relatively very few. 4,[11][12][13] In Ref. 4 , each LTE antenna, however, requires a metal-frame section much longer than the short edge of the smartphone.…”

“…In Refs. , the LTE MIMO antennas can cover one LTE LB and two LTE M/HBs; each LTE antenna therein requires a metal‐frame section much shorter than the short edge of the smartphone. However, it is noted that the two LTE M/HB antennas reported in Refs.…”