Novel Deployable Quasi-Yagi Monopole Antenna using Origami Magic Spiral Cube

Syed Imran Hussain Shah and Sungjoon Lim School of Electrical and Electronic Engineering

Chung-Ang University Seoul 156-756, Republic of Korea

engr.shahsyedimran@gmail.com, sungjoon@cau.ac.kr

Abstract- In this paper, a novel deployable quasi-Yagi monopole antenna is designed using origami magic spiral cube. The presented antenna consists of a driven monopole, a reflector and two directors, built on a low cost paper substrate. The driven element, the reflector and the directors are constructed in L-shape geometry to reduce the overall volume of the antenna. The monopole and the reflector are designed on the same magic cube, while the directors are realized on two different magic cubes. All the three magic cubes are stacked and joined with one another by using a double-sided thin adhesive film. The proposed origami antenna has the novelty in its design of easy folding and unfolding behavior. Under the unfolded state, the geometry is very compact (90% lesser in volume compared to the unfolded state), and can be easily transported and deployed in the unfolded state. The proposed antenna, operating at 1.8 GHz with peak gain of 7.3 dBi, has been numerically and experimentally analyzed in terms of its scattering parameters and radiation pattern. Keywords—Deployable antenna, origami antenna, reconfigurable antenna, Yagi-Uda antenna.

1. Introduction

Since the last few decades, Yagi antenna is getting considerable attention for numerous modern communication technologies, due to their interesting features like low cost, high radiation efficiency, high gain and low cross-polarization level. Various Yagi antennas have been reported in literature exploring all the above mentioned features. However, the Yagi arrays designed at frequencies lower than 5 GHz are bulky and deprived of convenient portability. Origami antennas can be a favorable solution to easily transport and deploy the Yagi antennas aimed for practical applications.

Origami technology, a paper folding technique, has gained increasing research attention owing to its light weight, simple design method, and flexible behavior. Numerous applications have been proposed in diverse fields, such as –complex origami models are designed in architecture, Origami telescope is presented for space exploration and origami stent is proposed for medical applications. This feature can also be exploited in antenna design due to their low cost and easy manufacturing procedures. Besides, various complicated geometries can be easily adopted using origami technology unable to model using conventional design procedures[1-3]. Recently, a few Yagi antennas have been reported using origami techniques. In [1], a

high gain Yagi antenna is presented using origami tetrahedron geometry, however the overall size of the antenna is quite large. A low cost frequency reconfigurable origami antenna is described in [2], but the geometry is unstable and inconvenient for repetitive folding and unfolding characteristic.

In this paper, a novel deployable quasi-Yagi monopole is presented using origami technique. The proposed geometry comprises L-shaped metallic patterns printed on low cost paper substrates, which are arranged in the shape of magic spiral cubes. The design is mechanically stable, easy to deploy, and can be used for repeated folding-unfolding operation, unlike the earlier reported origami antennas. The performances of the proposed antenna is numerically studied as well as experimentally verified.

2. Antenna Design and Performance

The geometry of the proposed spiral magic cube antenna in the deployed (unfolded) state is illustrated in Fig. 1. Firstly, three different origami magic cubes are constructed, where each of the cube is fabricated from two square paper sheets having the dimensions of 140 mm × 140 mm and thickness of 0.2 mm. The antenna consists of a driven element monopole, a reflector, and two directors, which are realized on these magic cubes. The monopole and the reflector are built on the same magic cube, whereas the directors are realized on different cubes.

Fig. 1. Geometry of deployable origami magic spiral cube Yagi antenna: L = 44, Lr = 20, Lg = 22, L1 = 20, Ld = 26, Wd = 3, (units: millimeters).

This research was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government (MSIT) (2018R1A4A1023826).

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

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Each of these elements have been constructed in L-shape geometry to reduce the overall antenna volume in the unfolded state. Copper film, having conductivity and thickness of 4.4 × 105 S/m and 0.1 mm, respectively, is used for the realization of antenna elements, due to its flexibility and durability. The proposed antenna was fabricated using paper and copper tape as the constituent elements for the substrate and the antenna elements, respectively. The final antenna prototype in the unfolded and folded states are illustrated in Fig. 2. The detailed step by step fabrication procedure of the origami spiral magic cube geometry will be presented in the conference presentation.

The proposed Yagi antenna is numerically analyzed in the commercial software Ansys high frequency structure simulator (HFSS). Paper substrate is initially characterized for the desired operational frequency, and its dielectric constant and loss tangent are found to be 1.8 and 0.04, respectively.

(a) (b)

Fig. 2. Fabricated prototype of the proposed origami magic spiral cube Yagi antenna in (a) unfolded state, and (b) folded state.

Fig. 3. Simulated and measured reflection coefficient of the proposed antenna in the deployed state

The length of the monopole is optimized to obtain the operational frequency at 1.8 GHz. Without any reflector or director, the monopole exhibits a peak gain of 3 dBi. To increase the gain, an L-shaped reflector is added on the back side of the bottom magic cube. This gives rise to an increased gain of 5.3 dBi. In order to further increase the gain of the proposed ntenna, two L-shaped directors are incorporated in the top magic cubes.

The geometries of the antenna elements have been made in L-shape to reduce the overall volume of the antenna in the unfolded state. All the geometric dimensions of the design are

optimized to increase the gain, while adding the directors. With single director addition, the antenna gain is increased to 6.5 dBi, while the second director increases the gain further upto 7.3 dBi. With subsequent addition of more number of directors, the gain becomes saturated, and thus not added in the antenna structure.

The proposed antenna, after optimization, was fabricated and experimentally validated. The simulated and measured reflection coefficient of the antenna is presented in Fig.3 and its measured radiation pattern is demonstrated in Fig. 4.

Fig.4. Measured 3-D radiation pattern at 1.8 GHz

3. Conclusion

In this paper, a novel low cost deployable quasi-Yagi monopole is presented by exploiting origami magic spiral cube. The proposed antenna is realized by joining three magic cubes together. On the first magic cube, the driven element and the reflector are realized, whereas two other magic cubes are used to add the directors for realizing higher gain. Owing to origami technique, the proposed antenna can be folded and unfolded comfortably. This gives rise to a compact design (occupies 90% smaller volume compared to the unfolded state), which can be conveniently transported and easily deployed in the unfolded state. Being designed on the paper substrate, the proposed antenna is also low cost. In future, various substrates will be explored to realize a robust and flexible origami antenna.

Acknowledgment

This research was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (018R1A4A1023826).

References [1] S. I. H. Shah, M. M. Tentzeris, and S. Lim, “Low-Cost Circularly

Polarized Origami Antenna,” IEEE Antennas and Wireless Propagation Letters, vol. 16, pp. 2026–2029, 2017.

[2] X. Liu, S. Yao, P. Gonzalez, and S. V. Georgakopoulos, “A novel ultra-wideband origami reconfigurable quasi-taper helical antenna,”IEEE Antennas and Propagation Society International Symposium, APSURSI 2016 - Proceedings, pp. 839–840.

[3] X. Liu, S. Yao, B. S. Cook, M. M. Tentzeris, and S. V. Georgakopoulos, “An Origami Reconfigurable Axial-Mode Bifilar Helical Antenna,” IEEE Transactions on Antennas and Propagation, vol. 63, no. 12, pp. 5897–5903, 2015.

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

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