Small‐size adjustable LTE/WWAN coupled‐fed loop antenna for mobile handset applications

Abstract

A compact reconfigurable coupled‐fed loop antenna of the mobile handset for multiband long‐term evolution (LTE)/wireless wide area network operation is presented. The antenna volume is 5 × 10 × 30 mm3 only, while the protruded ground has a width of 30 mm for mounting electronic components. The proposed antenna is consisted of a loop strip and a driven strip. Through the driven strip capacitively coupled to the loop strip, the antenna can generate a 0.25‐wavelength loop resonant mode to form the antenna's lower band to cover the GSM850/900 bands (824–960 MHz). The simple driven strip is also an efficient radiator to excite a resonant mode for the antenna's upper band to cover the GSM1800/1900/WCDMA Band1 bands (1710–2170 MHz). Moreover, when the chip inductor connected to the loop strip has been adjusted from 0 to 12 nH, the antenna's lower band can be shifted to lower frequency and cover the LTE Band17 band (704–746 MHz) and the antenna's upper band is not varied. This tunable technique can allow the loop antenna to cover more operating bands without adding the antenna volume. Detailed operating principle and performances of the proposed antenna are discussed in this article. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2687–2691, 2014

Dual‐band dual inverted‐F/loop antennas as a compact decoupled building block for forming eight 3.5/5.8‐GHz MIMO antennas in the future smartphone

“…To address the working principle of the dual‐band inverted‐F/loop antenna, Ant1 alone is studied; that is, other antennas (Ant2–Ant8) are not present to simply the analysis. Note that for operating in the 3.5‐GHz band, the antenna is operated as a gap‐coupled loop antenna shown in Figure B and denoted as Ant1a, in which the strip DE is not present. Note that the coupling gap has a width of 0.4 mm which capacitively excites the loop antenna to generate its quarter‐wavelength resonant mode as the antenna's lowest resonant mode .…”

Integrated yet decoupled dual antennas with inherent decoupling structures for 2.4/5.2/5.8-GHz WLAN MIMO operation in the smartphone

“…For either Ant1 or Ant2, the longer coupled‐fed end‐shorted strip (strip 1 or strip 1′) thereof is excited through the first coupling gap to provide a first loop resonant path (section ABCDE or A′B′C′D′E′, length 25.4 mm). This resonant path can contribute a 0.25‐wavelength loop resonant mode at about 2.45 GHz for the 2.4‐GHz WLAN operation and also generate a higher‐order resonant mode at about 6 GHz to widen the bandwidth of the antenna's high band. On the other hand, the shorter coupled‐fed end‐shorted strip (strip 2 or strip 2′) thereof is also excited through the second coupling gap to provide a second loop resonant path (section AFGHI or A′F′G′H′I′, length 9.6 mm) to contribute a 0.25‐wavelength loop resonant mode at about 5.5 GHz for the antenna's high band.…”

High‐isolation conjoined loop multi‐input multi‐output antennas for the fifth‐generation tablet device

“…Ant1 is excited using a feed strip (section AA 0 ), Similarly, Ant2 is formed by using section BB 0 as a feed strip to capacitively couple, through a coupling gap of 0.3 mm, to section DF which is also grounded to the system ground plane through the conjoined section DG. Both Ant1 and Ant2 can generate a quarter-wavelength loop resonant mode [31][32][33] in the desired operating band. In addition, it should be noted that Ant1 and Ant2 are conjoined together so that there is no spacing therebetween.…”