october 23~26, 2018 / paradise hotel busan, busan, korea ......in this paper, a compact printed...
TRANSCRIPT
An Eight-band WWAN/LTE By-Hinge Printed
Inverted-F Antenna on Laptop Computer
Shu-Chuan Chen1, Chong-Wei Liou2, Chung-I G. Hsu2 and Jia-Yi Sze1 1 The Department of Electrical and Electronic Engineering, Chung Cheng Institute of Technology, National Defense
University, Taoyuan 335, Taiwan
2 The Department of Electrical Engineering, National Yunlin University of Science and Technology, Yunlin 640, Taiwan
Abstract - This paper presents a printed inverted-F antenna
mounted on a laptop computer for eight-band WWAN/LTE
operations. The PIFA is inserted in an area bounded by the
right hinge and the two ground planes of the laptop so as to
integrate these metal surroundings as part of the radiation
structure. The resulting operating bands can cover the lower
frequency band of 698–960 MHz for LTE700/GSM850/900
operations and the higher frequency range of 1710–2690 MHz
for GSM1800/1900/UMTS/LTE2300/2500 operations.
Simulated efficiencies are mostly greatly than 50% except for
the frequencies near the lower edge of the lower frequency
band.
Index Terms —PIFA, WWAN antennas, LTE antennas,
laptop computer antennas
1. Introduction
Because of the rapid development of wireless
communications in recent years, laptop computers equipped
with a single antenna that can support the
LTE700/GSM850/900 bands at lower frequencies and the
GSM1800/1900/UMTS/LTE2300/2500 bands at higher
frequencies have been in great demand. This antenna was
conventionally mounted around the top edge of the display
ground plane [1]–[3], or, for the sake of saving space, inside
the hinge slot bounded by two ground planes and two hinges
[4]–[8]. In [6]–[8], it has been shown that when the
excitation antenna is placed inside the hinge slot, the metal
surroundings can be integrated as part of the radiation
structure, thus leading to greatly broadened operating bands.
In this paper, a compact printed inverted-F antenna (PIFA)
with two open-end arms is proposed to be placed in a
clearance area outside the hinge slot. The metal surroundings
are observed to provide part of the resonant current path for
the PIFA so that the greatly widened operating frequencies
can support the desired eight WWAN/LTE bands
2. Antenna Structure
Fig. 1 shows the geometry of a PIFA deployed in the
clearance area bounded by the right hinge, the display
ground plane, and the keyboard ground plane. These two
ground planes have the same area of 320 200 mm2, which
is approximately the size of a 14-inch laptop. The two hinges
of 15 5 mm2 are 200-mm apart, leaving a clearance area
of 45 5 mm2 on the right side of the right hinge and on the
left side of the left hinge. The PIFA pattern is printed on the
front side of a 45 5 mm2 FR4 substrate with dielectric
constant 4.4, loss tangent 0.02, and height 0.8 mm. In
simulation and experiment, the two ground planes and the
two hinges are all made of 0.2-mm-thick copper plates. The
back surface of the substrate, which is free of metal, is made
coplanar with the back surface of the hinges and the display
ground plane. The PIFA is fed by a 50- mini-coaxial cable
through connecting the center conductor and outer metal
braid of the cable, respectively, to the feeding point A and
the grounding point G that is on the keyboard ground plane
and that is nearest to point A. If regarded as starting from
point A, the PIFA pattern consists of three arms. The one
with a length of 25 mm is shorted to the ground through
point Gs; the one with a length of approximately 38.5 mm is
turned right and meandered to the open-end point B; and the
one with a length of approximately 52 mm is turned left and
meandered to the open-end point C.
Fig. 1. Configuration and structural parameters of the
proposed antenna implemented on a laptop.
3. Results and Discussion
Fig. 2 shows the simulated and measured return losses of
the proposed PIFA with metal surroundings in Fig. 1. For
convenience, the frequencies associated with the dips of the
inverted return-loss curves are called resonant frequencies. It
it found that there are five resonant frequencies pertinent to
the desired operating bands, two pertaining to the lower
frequency band of 698–960 MHz and three relevant to the
upper frequency band of 1710–2690 MHz. Although there
are some noticeable discrepancies between simulated and
[ThD1-5] 2018 International Symposium on Antennas and Propagation (ISAP 2018)October 23~26, 2018 / Paradise Hotel Busan, Busan, Korea
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measured return losses, the impedance bands with the return
loss greater than or equal to 6 dB are both wide enough to
support the desired lower and upper frequency regions.
Fig. 2. Simulated and measured return losses of the
proposed PIFA mounted on the laptop in Fig. 1.
Fig. 3. Current distributions on the PIFA..
Fig. 4. Simulated efficiency of the proposed antenna in
Fig. 1.
The current distributions for the five simulated resonant
frequencies are plotted in Fig. 3. The paths are denoted by
thick black lines for the currents on the PIFA and by dotted
lines for those coupled to the display ground plane and to the
right hinge. Obviously, mode 1 (5) is associated with λ/4
(3λ/4) resonance on the shorted arm and the right open-end
arm, whereas mode 2 (4) with λ/4 (3λ/4) resonance on the
shorted arm and the left open-end arm. In addition, the mode
3 current has a λ/4 path only on the right open-end arm.
Fig. 4 shows the simulated efficiencies. In the lower
frequency band, the efficiencies range from 45% to 89%. In
the upper frequency band, the efficiencies are in 54–87%. In
Fig. 5, we show at 745, 890, 1940, and 2500 MHz three-
dimensional radiation patterns. Note that the efficiencies of
the proposed antenna around the lower edge of the lower
frequency band are too low and need to be improved in the
future. In addition, parametric studies of the antenna design
and the measured radiation patterns as well as the
efficiencies will be presented in the conference.
Fig. 5. Simulated three-dimensional radiation patterns.
4. Conclusion
The research proposes an eight-band WWAN/LTE by-
hinge PIFA antenna for laptops. The right hinge and the two
ground planes of the laptop have been integrated as part of
the radiation structure. The resulting integrated antenna is a
very efficient radiating structure. Simulated efficiencies are
greater than 45% at most frequencies in the desired
frequency bands supporting the LET/WWNA operations,
making the proposed integrated antenna promising for
practical applications.
Acknowledgment
This work was supported by the Ministry of Science and
Technology, Taiwan (The Republic of China) under Grant
MOST 105-2221-E-606 -002.
References
[1] K.L. Wong and P.J. Ma, “Coupled-fed loop antenna with branch
radiators for internal LTE/WWAN laptop computer antenna,”
Microwave Opt. Technol. Lett., vol. 52, pp. 2662–2667, Dec. 2010.
[2] T.W. Kang, K.L. Wong, L.C. Chou, and M.R. Hsu, “Coupled-fed
shorted monopole with a radiating feed structure for eight-band
LTE/WWAN operation in the laptop computer,” IEEE Trans.
Antennas Propag., vol. 59, pp. 674–679, Feb. 2011.
[3] L.Y. Chen and K.L. Wong, “2.4/5.2/5.8 GHz WLAN Antenna for the
Ultrabook Computer with Metal Housing,” presented at Proceedings
of APMC 2012, Kaohsiung, Taiwan, Dec. 4–7, 2012.
[4] S.C. Chen and Y.C. Tsou, “Small-size LTE/WWAN two-strip
monopole exciter antenna integration with metal covers,” IEEE Trans.
Antennas Propagat., vol. 64, pp. 3707–3711, Aug. 2016.
[5] S.C. Chen and Y.C. Tsou, “Long-term evolution/wireless wide area
network monopole exciter antenna for slim laptop with full metal
cover,” Electronics Lett., vol. 52, pp. 794–796, May 2016.
[6] S.C. Chen and Y.C. Tsou, “Bandwidth Enhancement of a Monopole
Exciter by Using a Chip-Inductor-Loaded Shorted Strip,” Journal of
Electromagnetic Waves and Applications, vol. 30, pp. 1481–1492, Jul.
2016.
2018 International Symposium on Antennas and Propagation (ISAP 2018)October 23~26, 2018 / Paradise Hotel Busan, Busan, Korea
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