**Author details**

Y.F. Weng, S.W. Cheung, T.I. Yuk and L. Liu *Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong* 

#### **6. References**


[14] Y. J. Cho*, et al.*, "A miniature UWB planar monopole antenna with 5 GHz band-rejection filter," in *Microwave Conference, 2005 European*, 2005, p. 4 pp.

270 Ultra Wideband – Current Status and Future Trends

**Author details** 

**6. References** 

compared to 97% for the reference UWB antenna.

Y.F. Weng, S.W. Cheung, T.I. Yuk and L. Liu

[3] Available: http://www.wimaxforum.org/

*Letters,* vol. 42, pp. 315-316, 2006.

55, pp. 604-610, 2007.

good band-notched characteristics. The simulated and measured results have shown that substantial reductions in efficiency and peak gain can be achieved at the notch frequencies. In the time domain, the pulse responses of these notched antennas have been measured inside the quiet zone of the anechoic chamber in The University of Hong Kong. Fidelity has been used to evaluate the time-domain performance of these antennas. Results have shown that all these band-notched antennas designed have the fidelities of more than 85%,

*Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong* 

[1] [1] FCC, "First Report and Order: Revision of Part 15 of the Commission's Rules

[4] A. Kerkhoff and H. Ling, "Design of a planar monopole antenna for use with ultrawideband (UWB) having a band-notched characteristic," in *Antennas and Propagation* 

[5] H. G. Schantz*, et al.*, "Frequency notched UWB antennas," in *Ultra Wideband Systems and* 

[6] K. H. Kim*, et al.*, "Band-notched UWB planar monopole antenna with two parasitic

[7] T. G. Ma and S. J. Wu, "Ultrawideband Band-Notched Folded Strip Monopole Antenna," *Antennas and Propagation, IEEE Transactions on,* vol. 55, pp. 2473-2479, 2007. [8] J. Kim*, et al.*, "5.2 GHz notched ultra-wideband antenna using slot-type SRR," *Electronics* 

[9] A. J. Kerkhoff and L. Hao, "Design of a Band-Notched Planar Monopole Antenna Using Genetic Algorithm Optimization," *Antennas and Propagation, IEEE Transactions on,* vol.

[10] Y. F. Weng*, et al.*, "UWB antenna with single or dual band-notched characteristic for WLAN band using meandered ground stubs," in *Antennas & Propagation Conference,* 

[11] Y. F. Weng*, et al.*, "Triple band-notched UWB antenna using meandered ground stubs," in *Antennas and Propagation Conference (LAPC), 2010 Loughborough*, 2010, pp. 341-344. [12] S. W. Qu*, et al.*, "A Band-Notched Ultrawideband Printed Monopole Antenna," *Antennas* 

[13] W. J. Lui*, et al.*, "Compact frequency notched ultra-wideband fractal printed slot antenna," *Microwave and Wireless Components Letters, IEEE,* vol. 16, pp. 224-226, 2006.

Regarding Ultra-Wideband Transmission Systems," Apr. 2002. [2] Available: http://www.fcc.gov/pshs/techtopics/techtopics10.html

*Society International Symposium, 2003. IEEE*, 2003, pp. 830-833 vol.1.

*Technologies, 2003 IEEE Conference on*, 2003, pp. 214-218.

patches," *Electronics Letters,* vol. 41, pp. 783-785, 2005.

*2009. LAPC 2009. Loughborough*, 2009, pp. 757-760.

*and Wireless Propagation Letters, IEEE,* vol. 5, pp. 495-498, 2006.


[33] G. Marrocco, "Gain-optimized self-resonant meander line antennas for RFID applications," *Antennas and Wireless Propagation Letters, IEEE,* vol. 2, pp. 302-305, 2003.

**Chapter 12** 

© 2012 Liu et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 Liu et al., licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**Cable Effects on Measuring** 

L. Liu, S.W. Cheung, Y.F. Weng and T.I. Yuk

Additional information is available at the end of the chapter

and creates uncertainties to the design of the antenna.

http://dx.doi.org/10.5772/46080

**1. Introduction** 

**Small Planar UWB Monopole Antennas** 

Since the US-FCC assigned the ultrawide band (UWB) for unlicensed use in 2002, UWB technology has attracted much attention in both the commercial and academic domains. The characteristics of ultrawide bandwidth from 3.1 to 10.6 GHz and low power emission of - 41.3 dBm/MHz make it a promising candidate for different applications such as high speed communications and radar imaging systems. However, the requirements for impedance matching, constant gain, constant radiation patterns and high radiation efficiency over such a wide bandwidth for the UWB antenna become great challenges to antenna designers.

With the increasing demand for smaller wireless devices, planar antenna, with the advantages of compact size, low profile, low cost, ease of fabrication and ease of integration with RF circuits, appears to be more preferable for UWB applications. Among different planar antennas, monopole antenna has the simplest structure, compact size and omnidirectional radiation pattern and so is one of the best candidates. For a planar monopole antenna to work properly, the ground plane is required to be electrically large enough to approximate an infinite-ground plane and so occupies a large portion of the overall antenna size. Thus to design a compact UWB monopole antenna, the ground plane is usually the one to be minimized. Designing a planar monopole antenna with a small ground plane to cover the UWB is not a difficult task and can be achieved through different techniques [1-7]. The design is usually done using computer simulation. In carrying out the design in simulation, the antenna is fed directly with a signal source without using a feeding cable. However, when the final design is completed and prototyped for measurements, a feeding cable is normally used to connect the antenna to the measurement system. The small ground plane cannot approximate an infinite ground plane well and causes the currents to flow back to the outer surface of the feeding cable, resulting in secondary radiation. This leads to discrepancies between the simulated and measured performances of the antenna

