Compact Multiband Omni-Directional Printed Antennas A. A. Saeed*
Shoukry I. Shams(1), A. M. M. A. Allam(2)
Student, Information Engineering and Technology (IET) German University in Cairo Cairo, Egypt
[email protected]
(1) T.A., M.sc., IET, (2) Professor, PhD, IET
German University in Cairo Cairo, Egypt
Abstract------This article presents a design of a printed antenna with simply shaped radiator element for multi-operating bands of the wireless communication systems. With a simple design configuration including different U shapes on a printed FR4 substrate, the proposed antennas covering the GPS (1575 MHz), Mobile-WiMAX (3400–3600 MHz) and 5 GHz WLAN (5150– 5350/ 5725–5825 MHz) bands. Several properties of the proposed antennas in multiband operation, such as radiation pattern and measured return loss are numerically and experimentally investigated. Index Terms------Multiband, communication.
I.
printed
antennas,
wireless
INTRODUCTION
M
ULTIBAND operations of wireless communications systems have developed rapidly, increasing the need for low-profile, low-cost, multiband antennas for mobile terminals. Many antennas with broadband and multiband functionality, including inverted-F antennas, monopole antennas, planar antennas and slot antennas, have been described in recent years [1]–[7]. Printed antennas with moderate radiating characteristics can be operated at multiple frequency bands. They support dual-band operation in the wireless local area network (WLAN) communication systems [1]–[3]. The printed antennas presented in this work have a simple configuration and slot form. It is applied for use in GPS (1575 MHz), Mobile-WiMAX (3400–3600 MHz) and 5-GHz WLAN (5150–5350/5725–5825 MHz) applications. II.
ANTENNA DESIGN
Fig. 1 shows the geometry of the proposed printed antenna with a double-layered metallic structure for multiband applications. It is printed on a 1.5-mm-thick FR4 substrate with a relative permittivity of 4.4 and dimensions 45 × 15 mm² . The design includes a U-shaped ground plane. A feed microstrip line is matched in both sides using λ/4 transformers. The optimal dimensions of proposed antennas are Wf = 2.8 mm, Wm = 1.7 mm, Wp1 = 2 mm, Wp2 = 15 mm, Ws = 1 mm, Ws1 = 4 mm, Ws2 = 2 mm, Lf = 5 mm, Lm = 22 mm, Lp1 = 7.2 mm, Lp2 = 6.6 mm, Ls = 0.5 mm, Ls1 = 2.2 mm, Ls2 = 4.7 mm, Lstrip = 6 mm, Lstrip1 = 1.5 mm, Lstrip2 = 4 mm, Wstrip = 1 mm, Wstrip1 = 4 mm, Wstrip2 = 2 mm, For the ground Wg = 15 mm, Wg1 = 3 mm, Wg2 = 4.5 mm, Lg = 13.1 mm, Lg1 = 11.9 mm, Lg2 = 0.5 mm, For the U-shape Wu = 2.3 mm,
Figure 1. Antenna Design.
Figure 2. Modified Desig with the U-shape inserted.
Wu1 = 1.7 mm, Lu = 6 mm, Lu1 = 8 mm and T = 5 mm. The dimensions of the antennas are determined using Ansoft HFSS simulation electromagnetic software, and then verified experimentally. The designs with and without the U-shaped are investigated and the effect of the U-shape dimensions are discussed. III.
RESULTS AND DISCUSSIONS
For antenna 1, when changing Lstrip the cutoff at the upper frequency is shifted from the required band as shown in figure 5, similar effect when changing Wstrip as shown in figure 6. Figure 7 shows the simulated and measured return loss of the proposed printed antenna with simple and low profile structure for GPS, WLAN at around 1575 MHz and 5-GHz WLAN (5150–5350/5725–5825 MHz) after optimizing the previous dimensions for achieving the required bands.
Figure 3. Top layer of the fabricated antenna.
Figure 4. Bottom layer of the fabricated antenna. Figure 7. Simulated and measured reurn loss for antenna design.
After inserting the U-shape shown in figure 2, MobileWiMAX (3400–3600 MHz) is added to the GPS application. When minimizing Wu to 0.3 mm, the required band for WiMAX was lost. At Wu = 1.3 mm the antenna has selective return loss for DCS1800 (1710-1880) MHz, PCS1900 (18801900) and UMTS (1920-2170) as shown in figure 8. Similarly changing Wu1 and T dimensions, the same results are achieved as shown in figure 9 and 10. Figure 11 shows the simulated and measured return loss of the modified printed antenna.
Figure 5. Optimization for the Lstrip.
Figure 8. Optmization for Wu.
Figure 6. Optmization for the Wstrip.
The antenna designs are symmetrical for the sake of achieving far field omni-directional patterns in the required bands as shown in figures 12. The solid line presents the coradiation and the dashed line presents cross-radiation.
a
b
c
d
Figure 9. Optimization for Wu1.
Figure 12. Radiation patterns for the proposed antennas.(a)3D polar plot, (b)Radiation pattern at 1.5 GHz, (c)Radiation pattern at 3.5 GHz and (d)Radiation pattern at 5.5 GHz.
IV. Figure 10. Optimzation for T.
CONCLUSION
Printed antennas were developed for multiband operation. Experimental results demonstrate that the simple design with the U-shaped ground plane are in a good agreement with the simulated results and with the appropriate tuning of dimensions, the appropriate operating bandwidth, measured return loss and radiation patterns for GPS (1575 MHz), Mobile-WiMAX (3400–3600 MHz) and 5-GHz WLAN (5150–5350/5725–5825 MHz) applications are presented. ACKNOWLEDGMENT The authors are greatly thankful for using the equipments provided by the German university in Cairo. REFERENCES [1]
[2] [3] Figure 11. Simulated and measered reurn loss for the modified design.
[4]
S.-H. Hwang, J.-I. Moon, W.-I. Kwak, and S.-O. Park, “Printed compact dual band antenna for 2.4 and 5 GHz ISM band applications,” Electron. Lett., vol. 40, no. 25, pp. 1568–1569, 2004. K. L. Wong, Compact and broadband microstrip antennas, John Wiley & Sons, New York, USA, 2002 J. Janapsatya, K. P. Esselle, and T. S. Bird, “A dual-band and wideband planar inverted-F antenna for WLAN applications,” Microw. Opt. Techn. Lett., vol. 50, no. 1, pp. 138–141, 2008. M. Martinez-Vazquez, M.Geissler, and D. Heberling, "Volume consideration in the design of dual-band handset antennas," in 2001 IEEE Antennas Propagat. Soc. Int. Symp. Dig., pp. 112-115.
[5]
[6]
[7]
[8]
P.-L. Teng, H.-T. Chen, and K.-L. Wong, “Multi-frequency planar monopole antenna for GSM/DCS/PCS/WLAN operation,” Microw. Opt. Techn. Lett., vol. 36, no. 5, pp. 350–352, 2003. R. Li, B. Pan, J. Laskar, and M. M. Tentzeris, “A compact broadband planar antenna for GPS, DCS-1800, IMT-2000, and WLAN applications,” IEEE Antennas Wireless Propag. Lett., vol. 6, pp. 25–27, 2007. D. Viratelle and R. J. Langley, "Dual-band printed antenna for mobile telephone applications," IEE Proc.-Microwave Antennas Propagat., vol. 147, pp. 381-384, Oct. 2000. Yi-Chieh Lee, Student Member, IEEE, and Jwo-Shiun Sun, "A New Printed Antenna for Multiband Wireless Applications", IEEE Antennas and Wireless Propagation Letters, vol. 8, 2009.
