Design Of Ultra Wide Band Patch Antenna

The rise of time-domain communication and the UWB technology applied to object-detection and high-data-rate transmission lead to the development of ultra-wide band antenna technique. Unlike the traditional frequency-domain communication systems, UWB employs short pulse to transmit signal. UWB antennas, which are employed to transmit and receive very short pulses, play a significant part in the time-domain communication systems. In this work, basic theory and knowledge are given first, in which the Vivaldi antenna is discussed in detail. To better understand the wide band radiation mechanism of Vivaldi antenna, the corresponding transmission-line model is given and discussed briefly. Secondly, based on such theories and methods, three different ultra-wideband antennas are proposed in this work.To solve the problem that the time-domain and frequency-domain transmission can’t co-exist harmoniously, an antenna, which can work in Bluetooth band and UWB band, is designed. This antenna is created by a modified electric-LC resonator. A tapered strip is used between the feed line and ELC structure to achieve ultra-wideband and good impedance match. At the same time, the equivalent circuit model of the electric-LC resonator is analyzed, which is useful to tune the resonance and control the bandwidth.Later, a band-notched UWB antenna is proposed with the same ELC structure. First, the radiating patch is bolded and the patch edge is chamfered to gain large bandwidth. To achieve better impedance match, a slot is etched on the ground plane. Second, by etching an ELC structure on the radiating patch, a UWB antenna with one stop band is proposed. The result shows the added structure don’t deteriorate the wide-band impedance match obviously. Finally, some critical parameters are studied, followed by the illustration of surface current and electric field to gain an insight into the influence of the etched structure.In order to make the microwave component smaller and compact, dual-band stop filter and UWB antenna are intergraded. In this work, a step impedance resonator and a one fourth wavelength resonator are placed near the feed line. The parameter study shows that by changing the ratio of impedances of SIR, the notched band can be easily tuned. A shorting via is employed to guarantee that the two notched bands can be tuned independently. The resonance of one fourth wavelength structure is corresponding to maritime satellite communication frequency band and the stop band located at WLAN band is produced by the SIR.