| With the social development, wireless communication becomes more and more important in people's lives. Antenna as an essential part in wireless communication, which has also been a rapid development. Now, development of common communications antennas are miniaturization, multi-band, broad band and new time-domain antenna.etc. All antennas have the same radiation principle, such as Wireless LAN (WLAN) antennas, WiMAX antennas, ultra-wide band (UWB) antennas and time domain antenna. Although studies of the antenna can not change the radiation theory, it can bring new technologies and new methods to better meet applications of specific frequency band and specific occasion.Four key of design were respectively given in second, third, fourth and fifth chapter of this paper.In the second chapter, an ultra-compact dual-band printed antenna is proposed. The dimension of this antenna is only 12×28×1mm3, and only 33% than those reported antennas in the author's vision. Connective and concentric double split rings (CCDSR) are used to generate two resonant frequencies in wireless local area network (WLAN) frequency bands. Tuning arms are added to the microstrip fed line, which can be used to tune the upper frequency band. The measured 10 dB bandwidth in the 2.44 GHz band is 140 MHz (2.37-2.51 GHz) and in 5.34 GHz is 1.23 GHz (4.86-6.09 GHz), covering the 2.4/5.2/5.8 GHz WLAN operating bands. Good radiations at these bands are also observed.In the third chapter, a new design of multi-frequency antenna is presented. The antenna comprises a direct-radiating patch and a parasitic C-shaped strip, which generate resonant modes to cover 2.4/3.6/5.2/5.8 GHz bands. The design was experimentally verified by constructing the antenna on a PTFE dielectric substrate and the size is 30×36×1mm3. The measured│S11│<10 dB (VSWR<2:1) bandwidth in the 2.4 GHz band is 550 MHz((2.3-2.536 GHz), and it covers the bandwidth required for 2.4 GHz WLAN. The 5.2/5.8 GHz resonant mode has a bandwidth of 1.44 GHz (4.67-6.11 GHz) covering 5.2/5.8 GHz WLAN bands. The obtained impedance bandwidth reaches 790 MHz (spans from 3.15 GHz to 3.94 GHz). A rigorous experimental evaluation confirms that the proposed antenna maintains good radiation.In the fourth chapter, a small-sized and planar antenna for integrated Bluetooth and ultra wideband (UWB) applications is presented with WLAN band-notched. A semicircular and a split ring slot resonators are embedded in the radiating patch for dual band-notched to reject the WLAN interference band. The antenna is fed by a special microstrip line, and it is built on PTFE (εr=2.4) substrate with the whole size of 20×46×1mm3. The antenna can operate in the 2.25-2.5 GHz and 3.0-10.75 GHz frequency range that covers the Bluetooth (2.4-2.484 GHz) and UWB (3.1-10.6 GHz) with band-notched of 4.96-5.29 GHz and 5.54-6.01 GHz. The time domain consideration is also applied which exhibits good performance with short pulses.In the fifths chapter, one kind of picosecond level single pulse generators is designed by new technology, which has lower requirement to low frequency of time domain antenna. Short-circuit coaxial line is added in the output section of zero-order Gaussian pulse source, that can genera single pulse without complex circuit components. Radius of circular pulse generators has only 20mm. The peak value of pulse is 37.4V, and the width of pulse is 600ps. |
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