Regular paper
A narrow-frame antenna for WWAN/LTE/WiMAX/WLAN mobile phones

https://doi.org/10.1016/j.aeue.2018.07.018Get rights and content

Abstract

In this paper, we present a novel narrow-frame antenna with a size of 75 × 8 × 5.8 mm3 for 5.7 in. mobile phones. The antenna mainly consists of a monopole with four branches that are coupled to a two-branch grounded strip. Our antenna is able to cover more bands than other narrow-frame antennas by excitation of several resonant modes. The improved range of the antenna covers the following eleven bands: LTE700, GSM850, GSM900, DCS, PCS, UMTS, LTE2300, LTE2500, LTE3400 (3400–3800 MHz)/WiMAX3.5 GHz (3400–3650 MHz), WLAN5.2 GHz (5150–5350 MHz) and WLAN5.8 GHz (5725–5875 MHz). Another advantage of the proposed antenna is that it does not need any lumped element to match the antenna. The working principles of the proposed antenna are thoroughly studied. A prototype of the proposed antenna is fabricated and measured, with the results in good agreement with the simulation results.

Introduction

Recent smartphone designs have much larger touchscreens which requires antennas with less ground clearance [1], [2]. Moreover, there is an increasing demand for multiband antenna to cover LTE, WWAN, WiMAX and WLAN [3], [4], [5]. However, it is challenging to incorporate multiband antennas covering the aforementioned range of wireless bands in large screen devices with a small non-ground portion [6], [7], [8], [9], [10], [11]. Previous work, using octa-band antennas with 8 mm or 6 mm of non-ground portion height [7], [8], [9], [10] were able to cover LTE700 (698–787 MHz), GSM850 (824–894 MHz), GSM900 (880–960 MHz), DCS (1710–1880 MHz), PCS (1850–1990 MHz), UMTS (1920–2170 MHz), LTE2300 (2300–2400 MHz), LTE2500 (2500–2690 MHz) bands. However, higher bands such as WiMAX3.5 (3400–3650 MHz), WLAN5.2 (5150–5350 MHz), WiMAX5.5 (5250–5850 MHz) and WLAN5.8 (5725–5875 MHz) were not covered. In [11], a nano-band antenna with 7 mm non-ground portion height is presented that can cover an additional band of LTE3400 (3400–3800 MHz). To the best of our knowledge, [7], [8], [9], [10], [11] are all the narrow-frame antennas with non-ground portion height of 8 mm or less that can cover at least eight bands of LTE700, GSM850, GSM900, DCS, PCS, UMTS, LTE2300, and LTE2500, shown in Table 1.

Generally, Monopole antennas are good candidates for wideband and multiband characteristics [12], [13]. Several techniques are used to employ this feature for fully covering different bands of mobile phones. For example, in [14], [15], [16], the monopole antenna is coupled to the grounded strips to generate multiple resonances. In this paper, we propose a multiband and narrow-frame antenna for a 5.7 in. mobile phone. Our antenna consists of a four-branch monopole that is coupled to a two-branch grounded strip with a non-ground portion height of only 8 mm. The excitation of several resonant modes in the design leads to more bandwidth enhancement in comparison with other narrow-frame antennas. The antenna can cover bands of LTE700, GSM850, GSM900, DCS, PCS, UMTS, LTE2300, LTE2500, LTE3400 (3400–3800 MHz)/WiMAX3.5 GHz (3400–3650 MHz), WLAN5.2 GHz (5150–5350 MHz) and WLAN5.8 GHz (5725–5875 MHz). In addition, no lumped element has been used in the design, which allows for easier and cheaper mass production.

The rest of this paper is organized as follows. In Section 2 we present the antennas configuration, which is followed by the working principles of the proposed antenna in Section 3. Then, Section 4 presents the simulation and measurement results. Finally, some concluding remarks are given in Section 5.

Section snippets

Antenna structure

Fig. 1 shows the configuration of the proposed antenna. The antenna is printed on 0.8 mm thick Rogers4003 substrate with dielectric constant of 3.55 and loss tangent of 0.0027. An overview of our design is shown in Fig. 1a. The dimensions of the substrate are 75 × 140 × 0.8 mm3. The antenna consists of a monopole with four branches that are coupled to a two-branch grounded strip. The monopole antenna is printed on the top layer of the substrate, while the ground plane and two-branch grounded

Analysis of the proposed antenna

To understand the working principles of our antenna, first, we compare its S11 results with the S11 results of four previous iterations of the antenna design. Then, we study L1, L2, L3 and L4 parameters, which are important for tuning of resonance frequencies, previously shown in Fig. 1c and d. Finally, we simulate and plot the vector surface current distribution of the different resonance frequencies. All the simulations have been done by time domain solver of CST Studio 2017 which is suitable

Measurement results

Fig. 9 shows a fabricated prototype of the proposed antenna. The simulated and measured results of S11 are in good agreement as shown in Fig. 10. The measured -6 dB bandwidths of the antenna are 310 MHz (681–991 MHz), 1080 MHz (1626–2706 MHz), 513 MHz (3300–3813 MHz), 243 MHz (5136–5379 MHz) and 378 MHz (5622–6000 MHz) at low band, middle-bands and high band, respectively. Therefore, the antenna can cover bands of LTE700 (698–787 MHz), GSM850 (824–894 MHz), GSM900 (880–960 MHz), DCS

Conclusion

In this paper, a novel multiband and narrow-frame antenna for LTE/WWAN/WiMAX/WLAN was proposed. The height of non-ground portion of the proposed antenna is only 8 mm. The working principles of the antenna were analyzed and studied. A prototype of the design was fabricated and tested. The simulated and measured results were in good agreement. Excitation of several resonant modes of the antenna provides coverage of ten bands of LTE700, GSM850, GSM900, DCS, PCS, UMTS, LTE2300, LTE2500, LTE3400

References (20)

  • S.A. Goswami et al.

    A compact monopole antenna for wireless applications with enhanced bandwidth

    AEU-Int J Electron Commun

    (2017)
  • P. Beigi et al.

    A novel small triple-band monopole antenna with crinkle fractal-structure

    AEU-Int J Electron Commun

    (2016)
  • Y. Ling Ban et al.

    Low-profile narrow-frame antenna for seven-band WWAN/LTE smartphone applications

    IEEE Antennas Wireless Propag Lett

    (2014)
  • Katsunori Ishimiya et al.

    Multiband loop handset antenna with less ground clearance

    IEEE Antennas Wireless Propag Lett

    (2013)
  • Han Jiang Liu et al.

    A Multi-broadband planar antenna for GSM/UMTS/LTE and WLAN/WiMAX handsets

    IEEE Trans Antennas Propag

    (2014)
  • Hui-Fen Huang et al.

    A small size three-band multi-functional antenna for LTE/GSM/UMTS/WiMAX handsets

    Progress In Electromagnetics Research Letters

    (2014)
  • Shu-Chuan Chen et al.

    Small-Size 11-Band LTE/WWAN/WLAN internal mobile phone antenna

    Microwave Opt Technol Lett

    (2010)
  • Changjiang Deng et al.

    A novel low-profile hepta-band handset antenna using modes controlling method

    IEEE Trans Antennas Propag

    (2015)
  • Yan Wang et al.

    Wideband monopole antenna with less nonground portion for octa-band WWAN/LTE mobile phones

    IEEE Trans Antennas Propag

    (2016)
  • Rundong Tang et al.

    Wideband monopole without lumped elements for octa-band narrow-frame LTE smart phone

    IEEE Antennas Wireless Propag Lett

    (2016)
There are more references available in the full text version of this article.

Cited by (5)

View full text