UWB Bow-Tie Antenna with WLAN/WiMAX Band Application

Minbeom Ko and Jaehoon Choi

Department of Electronics and Computer Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea

*choijh@hanyang.ac.kr (corresponding author)

Abstract – In this paper, a UWB bow-tie antenna with WLAN /WiMAX band application is proposed. The simulated 10 dB return loss bandwidth of the proposed antenna is ranging from 2.32 GHz to 10.6 GHz. In order to obtain the improved bandwidth and impedance matching, round slots are embedded on each round dipole arm and fan-shaped sectors are added on the feedline. The proposed antenna has omnidirectional radiation patterns at 2.5 GHz, 3.5 GHz, and 5.5 GHz and a quasi-omnidirectional pattern at 10 GHz, respectively. The peak gains are 1.79 dBi, 2.51 dBi, 3.66 dBi, and 4.39 dBi at 2.5 GHz, 3.5 GHz, 5.5 GHz, and 10 GHz, respectively.

Index Terms — Bow-tie antenna, ultra-wideband(UWB) antennas, slot.

1. Introduction

Since the Federal Communication Commission (FCC) allocated the 3.1 GHZ-10.6 GHz band to ultra-wideband (UWB) communication systems, there has been increasing interest in UWB communication systems. UWB communication systems are well known for their attractive features such as low cost, low power consumption, and high data transmission rate. Many researches have been conducted to design a UWB antenna with small size, wide bandwidth and ease of manufacture [1-6]. Various approaches have been investigated to improve the bandwidth of bow-tie antenna, such as using slot [1-3], rounded corners on radial surface [4], and self-complementary principle [5]. Recently, research on UWB antenna simultaneously covering other frequency bands is received great interest. However, a few studies have been conducted on the bow-tie antenna for covering UWB band and other wireless bands.

In this paper, we proposed a bow-tie antenna operating at WiMAX (2.4 GHz-10.6 GHz), WLAN (2.5 GHz-2.69 GHz), and UWB (3.1 GHz-10.6 GHz) bands. The proposed antenna has improved impedance matching characteristic and wide bandwidth by embedding a round slot on each rounded dipole arm [7] and employing fan-shaped sectors on the feedline.

2. Antenna Design and Its Performance

(1) Antenna Geometry Fig. 1 illustrates the geometry of the proposed antenna. The

antenna is designed on FR4 substrate with a thickness of 1.6

mm, dielectric constant of 4.4, and loss tangent of 0.02. The

overall size of the antenna is 20 mm 40 mm. Each rounded

dipole arm has a round slot. Extra fan-shaped sector with a

Fig.1. Geometry of the proposed bow-tie antenna. (l2 = 18 mm, l3 = 11 mm, w2 = 16 mm, w3 = 8 mm, g1 = 1.6 mm, t1 = 3 mm, r1 = 1.8 mm)

Reference 1 Reference 2

Fig. 2. Simulated return loss characteristics of reference 1, reference 2, and the proposed antenna.

radius of 1.8 mm is added at the edge of the feedline. All parameters shown in Fig. 1 are optimized by HFSS [8].

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

[ThP-16]

697

Fig. 3. Simulated radiation patterns at (a) 2.5 GHz, (b) 3.5

GHz, (c) 5.5 GHz, and (d) 10 GHz.

Fig. 4. Simulated surface current distributions at (a) 2.5 GHz,

(b) 3.5 GHz, (c) 5.5 GHz, and (d) 10 GHz.

(2) Results of Numerical Results

Fig. 2 shows the simulated return loss characteristics of the reference antenna 1, reference antenna 2, and the proposed antenna. Reference 1 is a rounded bow-tie antenna and reference 2 has a round slot on each bow-tie arm of a reference antenna 1. As is shown in Fig. 2, the reference 2 shows better impedance matching characteristic at high frequency (6 GHz-8 GHz) than reference 1. By embedding a fan-shaped sector on the feedline to reference 2, the proposed antenna obtains significantly improved bandwidth from 7.32 GHz to 10 GHz and enhanced impedance matching characteristic at high

frequency (6 GHz-8 GHz) band. Radiation patterns of the proposed antenna in E-plane and H-plane are illustrated in Fig. 3. Simulation results at 2.5 GHz, 3.5 GHz, 5.5 GHz, and 10 GHz are presented to verify the stable radiation performance. From Fig. 3, it is shown that the proposed antenna has near omnidirectional patterns at 2.5 GHz, 3.5 GHz, and 5.5 GHz. At 10 GHz, the antenna has a quasi-omnidirectional pattern. The peak gains are 1.79 dBi, 2.51 dBi, 3.66 dBi, and 4.39 dBi at 2.5 GHz, 3.5 GHz, 5.5 GHz, and 10 GHz, respectively. To understand the operational principle of the proposed antenna, simulated surface current distributions are illustrated in Fig. 4. In Fig. 4 (a)-(c), the entire part of dipole arms are activated at 2.5 GHz and bottom and top parts of the dipole arm are activated at 3.5 GHz and 5.5 GHz, respectively. Since the surface current distributions are similar to the dipole, the radiation patterns in Fig. 3 (a)-(c) are near omnidirectional. As shown in Fig. 4, the surface current distributions at operating frequencies are strong around the added fan-shaped sectors. Therefore, the fan-shaped sectors play an important role in the proposed antenna.

3. Conclusion

A UWB bow-tie antenna with WLAN/WiMAX band application is proposed in this paper. The improved 10 dB return loss bandwidth and impedance matching characteristics are achieved by employing round slots on each rounded dipole arm and embedding fan-shaped sector to the feedline. The proposed antenna has a stable radiation pattern and peak gain.

Acknowledgment

This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIP) (No. 2017R1A2B4002811).

References

[1] Angelopoulos, Evangelos s., Argyris Z. Anastopoulos, and Dimitra l. Kaklamani, “Ultra wide-band bow-tie slot antenna fed by a CPW-to_CPW transition loaded with inductively coupled slots,” Microwave Opt. Technol. Lett., vol. 48, pp. 1816-1820, 2006.

[2] Mehdipour, Aidin, et al., “Modified slot bow-tie antenna for UWB applications,” Microwave Opt. Technol. Lett., vol. 50, pp. 429-432, 2008.

[3] Liu, Jing, Deshuang Zhao, and Bing-Zhong Wang, “A beveled and slot-loaded planar bow-tie antenna for UWB application,” Progress in Electromagnetics Research M, vol. 2, pp. 37-46, 2008.

[4] Sayidmarie, Khalil Hassan, and Yasser A. Fadhel, “A planar self-complementary bow-tie antenna for UWB applications,” Progress In Electromagnetics Research C, vol. 35, pp. 253-267, 2013.

[5] Karacolak, Tutku, and Erdem Topsakal, “A double-sided rounded bow-tie antenna (DSRBA) for UWB communication,” IEEE Antennas and Wireless Propagat. Lett., vol. 5, pp. 446-449, 2006.

[6] Gao, Fei, et al., “Low-profile dipole antenna with enhanced impedance and gain performance for wideband wireless applications,” IEEE Antennas and Wireless Propagat. Lett., vol. 12, pp. 372-375, 2013.

[7] Qu, Shi-Wei, and Cheng-Li Ruan, “Effect of round corners on bowtie antennas,” Progress In Electromagnetics Research, vol. 57, pp. 179-195, 2006.

[8] Ansys HFSS. ver. 2015.2, Ansys Corporation, Pittsburgh, PA, 2017.

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

698