Research On Compact Printed Ultra Wideband Antenna

As the rapid development of the technology of mobile communication, microelectronics and integrated circuit, communication systems make a great progresstowards multi-band, compact, ultra-wideband and intelligent. As one key device,antenna is faced up with many new demands for multiply frequencies, miniaturizationand ultra-wide bands. Compared with traditional antenna, planar monopole microstripantenna has smaller structure, lower profile, lighter weight, lower cost and can beintegrated more easily, so it has became one important antenna pattern and researchhot gradually.This paper introduces the basic theories and analytical methods of the planarantennas and summarizes the implement methods of reducing antenna size, spreadingspectrum and obtaining notched bands. To meet the band requirements of majorwireless communication systems，two approaches of realizing ultra-wideband antennaare proposed in this paper: single (traditional) and multi-band (equivalent) ultra-wideband (UWB) antenna.Single-band UWB antenna has continuous operating band covering3.1~10.6GHz. There are two major matters to be solved in this antenna design. One problem isthat the bandwidth of traditional microstrip antenna is too narrow to meet the UWBneed. The other issue is that there are some spectrum overlaps between UWB andothers wireless systems, such as WiMAX (3.3~3.6GHz) and WLAN (5.15~5.35GHz，5.75~5.825GHz). In order to reduce and suppress interference from thosewireless communication systems, band-notched (stopband) characteristics at desiredfrequencies are necessary to the presented UWB antenna. In this paper, the operatingbandwidth is expended by modifying the shape of patch and ground plane, while dualband-notched characteristics at certain frequencies are achieved by etching twoC-shaped slots with total length of quarter-wave on the patch. Meanwhile, to makefull use of wide band as much as possible, just depending on the inclusion of twoelectronic switches, the antenna with dual reconfigurable band-notched characteristicsis emerged. The proposed antenna has available operating band of3.1~12.6GHzexcept the dual notched band of3.23~3.75GHz and5.03~5.96GHz. By controllingelectronic switches, the band-notched states can be selected.Multi-band UWB equivalent antenna has a variety of operating bands which can be applied in several wireless communication systems, so it can be equivalent to thetraditional UWB antenna in some sense. The proposed multi-band antenna has fiveoperating bands of1.94~2.22GHz,2.32~2.54GHz,3.08~3.78GHz,3.63~4.83GHz,4.82~6.85GHz, which can be reconfigurable by controlling the switches to loadcorresponding parasitic elements.