Design And Research Of Uwb Antenna For Ban Applications

Ultra-wide Band(UWB) communication technology has some remarkable advantages such as low cost, ultra-low power, high speed and so on. And UWB antennas are correspondingly designed with characteristics of compact structure, low profile, ultra-wide band, constant gain, stable radiation pattern and high fidelity in time domain. Body area network(BAN) is a popular wireless network which requires high quality of communication and security of body radiation absorption. So it is very promising to ultilize UWB technology with ultra-low power and design UWB antennas for BAN applications.Firstly this paper gives an overview of UWB technology, UWB antenna and BAN researches. Then a UWB omnidirectional antenna and a UWB directional antenna are proposed for BAN applications. Also, this paper discusses the interaction between antennas and human body when antennas are placed in the vicinity of human body.The radiating effect of metal ground is seldom considered in most antenna designs. This paper shows that a properly designed metal ground can serve as a cooperative lower-frequency radiator for reducing the antenna dimensions, broadening the bandwidth of the antenna, and achieving stable beam patterns over a wide frequency band. By introducing a ground-cooperative radiating structure(GCRS) into a defected hexagonal monopole antenna, a novel CPW-fed planar ultra-wideband antenna with smaller size and lower edge frequency is developed. The novel antenna has overall dimensions of 27*31*1.6 mm3, constant group delay of less than 0.8 ns, and uniform omnidirectional patterns over 2.38-11.8 GHz, which make it capable of stably and flexibly transmitting low-power UWB electromagnetic waves to reduce radiation absorption of human tissues in BAN applications.Due to high-data-rate transmission capabilities with low-power spectral densities, ultra-wideband(UWB) radio technology has been studied for decades and extended into the body area network(BAN) communications, which arouses extensive interest in designing UWB-BAN antennas. However, most of these antennas have omnidirectional radiation patterns, which just suits the standard of UWB communications and may result in near-body degradation of antenna performance and power absorption of human tissues in narrowband communications. On the contrary, UWB directional antenna with shielding structures is a feasible solution to near-body problems in both UWB and narrowband BAN applications.In this paper, a novel stacked UWB antenna with unidirectional wide-angle patterns is proposed. By properly introducing an open reflection cavity(ORC) and a parasitic E-shaped patch(PEP), the proposed antenna achieves good impedance bandwidth of 3.52GHz-10.64 GHz, considerable gains and high front-to-rear ratio, which make it avoid near-body performance degradation and reduce specific absorption rate(SAR) of human body both in UWB and narrowband applications. As a compact antenna with dimensions of 50*50*10 mm3, it is very promising for BAN applications especially in the wireless off-body green communications.