Dual‐wideband U‐shape open‐slot antenna for the lte metal‐framed tablet computer

Abstract

The open‐slot antenna is very suitable for applications in the metal‐framed tablet device, such as the tablet computer, to achieve a low profile with wideband or multiband operation. This article presents a U‐shape open‐slot (U‐slot) antenna with a low profile of 7 mm to the top edge of the metal‐framed tablet computer for the LTE operation. The U‐slot has a simple structure of length 70 mm and the two slot openings thereof are disposed at the metal frame. The U‐slot antenna is fed using an end‐shorted 50‐Ω microstrip feedline, with a wideband matching network embedded therein. The antenna can support a 0.5‐wavelength slot resonant mode supported by the U‐slot itself and a 0.25‐wavelength slot resonant mode created by the open‐slot radiator (denoted as Slot 1 in this study) formed between one slot opening and the microstrip feedline as a virtual shorting. By further using an inverted‐U strip connecting across the U‐slot, the antenna can create an additional open‐slot radiator (denoted as Slot 2 in this study) to generate a 0.25‐wavelength slot resonant mode at lower frequencies. The resonant modes supported by the U‐slot, Slot 1, and Slot 2 can form two wideband operating bands to cover the LTE operation in the 698–960 and 1710–2690 MHz bands. Details of the proposed U‐slot antenna and the effects of the inverted‐U strip connecting across the U‐slot and the matching network are addressed. Experimental results of the fabricated U‐slot antenna are also presented. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2677–2683, 2015

Reconfigurable 3-D Slot Antenna Design for 4G and Sub-6G Smartphones with Metallic Casing

“…Slot antennas are widely adopted as an alternative for mobile antenna designs [10][11][12][13][14][15][16]. Two folded slot antennas were introduced in [10,11] to cover dual bands.…”

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

“…It has been shown that the open‐slot antenna is promising to be applied in the metal‐framed slim mobile device such as the smartphone and tablet computer for the LTE (long‐term evolution) operation . The metal frame around the slim mobile device can increase the robustness thereof and can also be used as an extended ground portion of the open‐slot antenna disposed in the system ground plane therein.…”

“…However, it is noted that many reported LTE open‐slot antennas disposed along one edge of the mobile device can provide one LTE low band (LB) below 1 GHz and one LTE middle/high band (M/HB, 1710–2690 MHz) only. For the metal‐framed smartphone application, two such open‐slot antennas can be disposed at two (top and bottom) short edges thereof to be applied for the 2 × 2 LTE MIMO (multi‐input multi‐output) operation .…”

“…For the 4 × 4 LTE MIMO operation to achieve an even higher channel capacity, which is demanded in some near future smartphones, two additional open‐slot antennas providing two extra LTE LB and/or two LTE M/HB are required. However, owing to very limited space available in the modern smartphone, the presently reported open‐slot antennas are not suitable to be applied for the 4 × 4 LTE MIMO operation.…”

Bandwidth enhancement of a slot antenna with an open stub

“…However, it is difficult to apply to the slot antenna because the characteristics of the impedance are different from those of the IFA. A slot antenna with open end is proposed to increase the antenna bandwidth . However, in actual practice, this requires cutting the metal frame, which places constraints on the design options.…”