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.

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2018 International Symposium on Antennas and Propagation (ISAP 2018)October 23~26, 2018 / Paradise Hotel Busan, Busan, Korea

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