A Design of an Ultra-Wideband Coplanar Waveguide Antenna

A Design of an Ultra-Wideband Coplanar Waveguide Antenna

Dong- min Deng

Institute of Antenna and Microwave Techniques Tianjin University of Technology and Education Tianjin, China

Hong- xing Zheng*

Institute of Antenna and Microwave Techniques Tianjin University of Technology and Education Tianjin, China

AbstractA kind of the small Ultra-wideband antenna is proposed in this paper. Its size is 34 mm x 30 mm x 1.6 mm, which is smaller than the other normal ultra-wideband antennas. And this design uses a shape of the annular umbrella to substantially increase the bandwidth. Its impedance bandwidth is from 1.1 GHz to 9.6 GHz. The antenna feed through coplanar waveguide. And its structure is simple and integration is easy. In addition, the HFSS simulation results show that this kind of antenna has the very good impedance and radiation characteristics within the whole working frequency band, which is used in the broadband wireless communication system.

KeywordsUltra-wideband antenna; Annular umbrella; Coplanar waveguide feed; Wireless communication

1. INTRODUCTION

   Ultra-wideband signal refers that relative bandwidth in – 10dB is greater than 20% or absolute bandwidth is more than 500M [1]-[4]. With the rapid development of wireless communication technology, people have further requirements for the size, structure, shape and performance parameters of the ultra-wideband antenna [5]-[6]. Ultra-wideband technology is widely used in medical and health, disaster rescue, geological exploration and other fields, and it becomes a research hotspot in recent years.

   This antenna uses the coplanar waveguide (CPW) structure [7]-[13]. There are many kinds of antennas with coplanar waveguide feed, such as coplanar waveguide feed broadband antenna [14]-[17], coplanar waveguide feed circular polarization antenna [18]-[23], coplanar waveguide feed multi-mode antenna [24]-[25]. CPW has the following advantages: first, the ground layer of CPW is in the same layer of medium plate with the signal lines, easy to connect other microwave devices in series or in parallel rather than drill hole on the substrate, which can realize the miniaturization of circuit and signal integrity; At the same time, the parasitic parameters is so small that can be neglected; It is easy to improve the density of integrated circuit. Second, CPW of dispersion characteristics of a transmission line is better than that of the microstrip line, and the circuit is suitable for the application of broadband antennas; Moreover, the radiation loss is relatively small, and CPW can significantly improve the polarization purity and work efficiency of the antenna. Finally, CPW can transfer the odd pattern and even pattern signal, which can increase the flexibility of the antenna design.

   CPW antenna consists of two parts, one is feed part and the other is radiating part. Feed part adopts coplanar waveguide, whose benefit is that feed layer and antenna radiating surface can be on the same plane. Thus, the antenna can easily connect with the radio frequency circuit of back end, which can also easily integrate with PCB circuit. And it can improve the antenna impedance matching characteristics to some extent.

   This paper is from the simple rectangular patch antenna [26], through the reasonable design of antenna patch [27], with coplanar waveguide feed way, to guarantee the realization of the ultra-wideband antenna.

2. STRUCTURE DESIGN

   1. Design principle of CPW planar monopole antenna

      r

      L

      Fig. 1. The cylinder model

      Fig. 2. The rectangle radiation patch monopole antenna

      The size of the planar monopole antenna is mainly determined by the low frequency band. For regular shape radiation patch of the planar monopole antenna, the low frequency point whose standing wave ratio reaches a certain specified value can be calculated by the cylinder approximation method. The figure 1 and figure 2 show the basic model of the cylinder. The cylinder can get a rectangle through cutting along the bus, which is the rectangular patch to estimate, as shown the rectangle radiation patch monopole antenna.

      Low frequency point of the antenna can be estimated by formula 1, where fL is the low frequency point frequency, and the units of L, r and g is mm, which can get a better approximation, through it an antenna prototype can be preliminarily designed.

      Fig. 4. Rectangular reference radiation patch antenna

      f 72

      L L r g

   2. The structure design of coplanar waveguide feed annular umbrella antenna

   The antenna is printed on the dielectric substrate whose size is 34 x 30 mm2. In this paper, the dielectric substrate use the FR4 material which relative dielectric constant was 4.4, and its thickness h is 1.6 mm. The antenna feeds by coplanar waveguide, and its ground is the same layer with the radiation patch. Feed structure is equivalent to the complanation of coaxial. At the same time, ground layer can also be seen as part of the radiation patch. The ultra-wideband antenna which uses the coplanar waveguide feed has the advantages of small size and easy integration.

   The radiation patch of Ultra-wideband antenna can be designed to a variety of different shapes, and this design uses annular umbrella shape of patch to substantially increase the work bandwidth to ensure the realization of ultra broadband. The shape of radiation patch as shown in figure 3.

   Fig. 3. The structure annular umbrella antenna

3. PARAMETERS DESIGN

   This paper uses commercial electromagnetic simulation software AnsoftHFSS15.0 to simulate and optimize the parameters, and is respectively compared with rectangular reference radiation patch antenna and Y shape coplanar waveguide antenna, as shown in figure 4 and figure 5.

   Fig. 5. Y shape coplanar waveguide antenna

   Rectangular reference radiation patch antenna is the rectangular radiation patch antenna. It is made up of the simple rectangular patch, whose feeder with a barron line in order to achieve impedance matching. And its length and width is respectively 30.21mm and 37.26mm. Its return lost is as shown in figure 6, which shows that the bandwidth is only 0.15GHz. (S11<-10dB). By adjusting the length and width of the rectangular patch, it can change the working frequency of antenna. And VSWR of rectangular patch antenna is as shown in figure 7.

   Fig. 6. Return lost of rectangular patch antenna

   Fig. 7. VWSR of rectangular patch antenna

   Antenna 2 uses Y type coplanar waveguide antenna. The length and width of patch is respectively 4.5mm and 18mm. The simulation result in figure 8 shows that the bandwidth can be improved to 7.5 GHz. It can meet the job requirements of ultra-wideband, but the frequency band is not rational in low frequency. The VSWR of antenna 2 is as shown in figure 9.

   Fig. 8. Return lost of Y shape antenna

   Fig. 9. VWSR of Y shape antenna

   The band of umbrella radiation patch antenna will be further widen on the basis of Y shape antenna. When the parameters of antenna are as shown in table 1, the simulation results show that the bandwidth will further widen to 8.5GHz. And it also has the good radiation in low frequency band, as

   shown in fiure 10. And the VSWR of umbrella radiation patch antenna is as shown in figure 11.

   TABLE I. THE PARAMETERS OF THE ANTENNA

   parameter	L	L1	L2	L3	L4	S
   Size/mm	13	21	30	18	4.5	1
   parameter	W1	W2	W3	Wf	g	h
   Size/mm	2	5	1.7	3.6	0.4	1.6

   Fig. 10. Return lost of annular umbrella antenna

   Fig. 11. VWSR of annular umbrella antenna

   Fig. 12. The antenna structure

   As shown in figure 12, these are return lost of three antennas. From it we can clearly see the rectangular patch antenna only have a radiant point on the 6 GHz, and the bandwidth is very narrow. When using coplanar waveguide feed, at the same time to change shape to Y type, the working band of antenna will substantially increases from 2.4 GHz to 10 GHz. Under the premise of without changing the coplanar waveguide feed to change the radiation patch shape into a annular umbrella, it can further increase the bandwidth and

   300

   270

   330

   0 xoy

   30 xoz

   60

   90

   work effectively from 1.1 GHz to 9.6 GHz, and it has good performance in low frequency band.

   At the same time, figure 13 presents direction figure of xoy plane and xoz plane of annular umbrella coplanar waveguide antenna in the frequency point of 1.5GHz, 3GHz, 5GHz, 7GHz and 9GHz. By figure can be seen, annular umbrella radiation patch antenna has good omnidirectional radiation in the whole work frequency from 1.1GHz to 9.6GHz. Although in high frequency part the directional of the work frequency deteriorates, but it still meets the requirements of design and production.

   240

   300

   210

   330

   180

   7GHz

   0

   150

   30

   120

   60

   xoy xoz

   300

   270

   330

   0 xoy

   30 xoz

   60

   90

   270

   240

   210

   180

   9GHz

   150

   90

   120

   240

   120

   Fig. 13. Direction figure of the antenna

   210

   180

   1.5GHz

   150

   The measurement of annular umbrella radiation patch antenna uses AV3629 vector network analyzer. Figure 14 shows the simulation and measurement results, which shows

   0 xoy

   the measurement results and the simulation result are

   300

   270

   240

   330

   210

   180

   3GHz

   30

   150

   xoz

   60

   90

   120

   approximately the same. The deviation is mainly that the dielectric constant of medium plate is not uniform, or due to the size deviation in the antenna processing and the SMB connectors welding, or because of the measurement environment factors. But these deviations are in the acceptable range. And the real antenna is as shown in figure 15.

   300

   270

   240

   330

   xoy

   0 xoz

   30

   60

   90

   120

   210

   180

   5GHz

   150

   Fig. 14. Simulation and measurement results of antenna

   Fig. 15. Real figure of the annular umbrella Antenna

4. THE CONCLUSION

This article presents a new kind of ultra-wideband coplanar waveguide antenna and uses software AnsoftHFSS15.0 to simulate. With rectangular patch antenna radiation and Y type radiation patch antenna compared, the results show that the antenna working bandwidth is bigger than others, which can meet the requirements of a variety of market frequency, and the radiation pattern also approximately meets the demand of omnidirectional nature. At the same time, the antenna has the characteristics of small size, easy processing, simple structure, and easy integrating with microwave circuit. And it can be effectively used in the wireless communication system.

ACKNOWLEDGMENT

I would like to show my deepest gratitude to my supervisor, professor Hong-xing Zheng, a responsible and resourceful scholar, who has provided me with valuable guidance in every stage of the writing of this thesis. Without his enlightening instruction, impressive kindness and patience, I could not have completed my thesis. His keen and vigorous academic observation enlightens me not only in this thesis but also in my future study. I shall extend my thanks to teachers and students from Tianjin University of Technology and Education, for their encouragement and support.

REFERENCES

1. Wang Yiqiang, Sun Gang and Hou Xiangbo, Uwb technology research and application, Communications technology, 42(3), pp.70- 75, 2009.

2. Li Fuchang, Uwb technology development situation and prospects, Communication & Information Technology, 167(3), pp.70-73. 2007.

3. Zhang xinyue, Shen Shuqun, Uwb wireless communication technology and its development prospect, Data Communications, 2004.

4. BENDEDETTO Maria-Gabriella Di and GIANCOLA Guerino, Understanding ultra wide band radio fundamentals, Beijing: Publishing House of electronics industry, 2005.

5. A. Kerkhoof and H. Ling, A parametric study of band-notched UWB planar monopole antennas, IEEE Antenna Propag Soc Int Symp, 2004, 2 (6): 1768-1771.

6. Zhao Han, The development situation and trend of modern wireless communication technology in the future, Technological Development

   of Enterprise, 30(16), pp.88-90, 2011.

7. L. J. Rogla, J. Carbonell and V. E. Boria. Equivalent circuit representation of Left-handed media in coplanar waveguide technology, Microwave Conference, European 2005, 1: 4-6.

8. S. Seo, S. Park and J. Joung, Micro pattering of Nano Metal Ink for printed circuit board using Inkjet Printing Technology, J. of the Korean Soc.Prec.Eng, 2007, 24: 89-96.

9. Kiasat Yasamman, Alphones A.A CRLH CPW leaky-wave antenna with reduced beam squinting, APMC2008, 2008.

10. S. Simion, G. Sajin and R. Marcelli, Silicon resonating based on CWP composite Right/Left-handed transmission line, Proceedings of the 37th European Microwave Conference, Munich Germany, Oct 2007: 478-481.

11. A, Rida, L. Yang and R. Vyas, Novel manufacturing processes for ultra-low-cost paper-based RFID Tags with enhanced wireless intelligence, Procs.57th IEEE-ECTC Symp, Sparks, NV, 2007: 733.

12. L. Yang and M. Tentzeris, Design and characterization of novel paper- based Inkjet-Printed RFID and Microwave Structures for Telecommunication and sensing applications, Digest IEEE Intl. Micro. Symp.Honolulu, HI, 2007: 1633.

13. Lee Hee Jo, Seo Shanghoon and Yun Kwansoo, RF performance of CPW transmission line fabricated with Inkjet printing technology, APMC2008, 2008.

14. Ling Yinsong, Yang Xiaodong and Liu Chengyuan, The study of coplanar waveguide feed of ultra-wideband antenna, In: Journal of Electronic Measurement and Instrument, 2014, 242: 222-226.

15. R. Chair, A. A. Kishk and K. F. Lee, Ultrawide-band coplanar waveguide-fed rectangular slot antenna, IEEE Antenna Wirel. Propag Lett, 2004, 3: 227-229.

16. Y. Kim and D. H. Kwon, CPW-fed planar ultra wideband antenna having a frequency band notch function, Electron. Letters, 2005, 41(7): 403-405.

17. Ruan Chengli, The theory and technology of ultra-wideband antenna, Harbin: Harbin institute of technology press, 2006.

18. S. Y. Suh, W. Stuzman and W. Davis, A novel cpw-fed disc antenna, IEEE AP-S Int. Symp. Dig, 2004: 2919-2922.

19. T. N. Chang and G. A. Tsai, A wideband coplanar waveguide-fed circularly polarized antenna, IET Microwaves, Antennas & Propagation, 2008, 2(4): 343347.

20. Sze Jia Yi and Chang Chi Chaan, Circularly polarized square slot antenna with a pair of inverted-L grounded strips, IEEE Antennasand Wireless propagation Letters, 2008, 7: 149-151.

21. Chien Jen Wang, Chia Hsien Lin, Yen Chih Lin, A circularly polarized antenna for application of GPS and DCS, Proceedings of iWAT2008, Chiba Japan, 2008: 159-162.

22. I. C. Deng, J. B. Chen and Q. X. Ke, A circular CPW-fed slot antenna for broadband circularly polarized radiation, Microw. Opt. Technol. Lett, 2007, 49(11): 2723-2728.

23. Hakim Aissat, Laurent Cirio and Marjorie Grzeskowiak, Reconfigurable polarized antenna for short-range communication systems, IEEE Trans. MTT, 2006, 54(6): 2856-2863.

24. J. M. Laheurte, Unilanar monopulse antenna based on add/even mode excitation of coplanar line, Electronics Letters, 2001, 37(6): 338-340.

25. E. Gschwendtner, Ultra-Broadband Car Antenna for Communications and Navigation Applications, IEEE Trans on AP, 2003, 51(8): 2020- 2027.

26. Gao Xingjun, Wang Guangmin, Zhu li and Liang jiangang, A new type of broadband microstrip slot antenna design, In: Journal of university of electronic science and technology of China, 2007, 36, (5): 883-886.

27. Li Mingyang, Liu min and Yang fang, HFSS antenna design, Beijing: Publishing House of electronics industry, 2011.