Small‐Size Planar LTE/WWAN Antenna and Antenna Array Formed by the Same for Tablet Computer Application

Abstract

For eight‐band LTE/WWAN operation (704–960/1710–2690 MHz) in the Ultrabook or thin‐profile tablet computer, a planar antenna of simple structure and small size is presented. The proposed antenna is obtained by modifying a simple planar inverted‐F antenna and can be printed on one surface of a thin FR4 substrate of size 10 × 45 mm2 only. The antenna's lower band bandwidth is greatly widened by embedding a proper chip capacitor of 2.7 pF at the feeding strip. This chip capacitor combines with the antenna's shorting strip can control the excitation of a parallel resonance to modify the impedance matching of the antenna's lower band such that a widened bandwidth is easily obtained to cover the LTE700/GSM850/900 operation. Conversely, the antenna's upper‐band bandwidth is also greatly enhanced by using a coupled section in the antenna's radiating strip and adding a parasitic shorted strip near the feeding strip, which lead to multiple resonant modes excited to form a wide bandwidth (>1 GHz) to cover the GSM1800/1900/UMTS/LTE2300/2500 operation. Owing to its small size and simple structure, the proposed antenna is very suitable to be applied in achieving an antenna array with high isolation for MIMO or dual talk (dual WWAN) operation. Promising high‐isolation antenna arrays formed by the proposed antennas are presented. The obtained isolation between the antennas in the antenna array is better than 12 dB, and the envelope correlation coefficient is less than 0.15 for frequencies over the LTE/WWAN bands. Details of the proposed antenna and antenna array are presented. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1928–1934, 2013

Four LTE low‐band smartphone antennas and their MIMO performance with user's hand presence

“…For the 2 × 2 multiple‐input multiple‐output (MIMO) operation to achieve enhanced channel capacity, two long‐term evolution (LTE) antennas are required to be embedded in the smartphone . It is also expected that the 4 × 4 MIMO operation can provide much higher channel capacity than the 2 × 2 MIMO operation .…”

Planar small-size LTE/WWAN tablet computer antenna with eight-band operation

“…Additionally, as for the overall antenna volume of only 35 × 10 × 0.8 mm 3 (280 mm 3 ), the proposed antenna has the merit of an antenna size at least 22% less than the smallest dimension of 45 × 10 × 0.8 mm 3 for the LTE/WWAN internal antenna in a tablet computer. [6] Finally, the proposed monopole strip antenna design is more feasible than those above-mentioned ones [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] for embedding into the tablet computers. Moreover, the internal antennas and the user body is less than 20 cm apart in distance during device use.…”

“…Therefore, to fulfill the 698-960/1710-2690 MHz bands and suitably embed it into a limited space, a small-size multiband antenna is the most optimal candidate of providing commercial broadband coverage in the bandwidth specifications of the 4G (LTE/ WWAN) system. The various applications of several planar monopole antennas (MAs) developed for LTE/WWAN operations include tablet computers, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] laptop computers [18][19][20], and mobile phones. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] However, those presented antenna designs have the drawbacks in the larger antenna size [3][4][5][6][7][8][9][10] or insufficient operating bandwidth [11][12][1...…”

Coupled‐fed inverted‐F antenna using an inverted‐F coupling feed for small‐size LTE/WWAN tablet computer antenna

“…In , the antenna uses a single‐branch radiator and an additional parasitic shorted radiator to achieve two wide bands to cover the LTE/WWAN operation. In this design, the antenna's metal pattern occupies a planar area of 10 × 45 mm 2 only and is suitable for slim tablet computer applications.…”