An Approach to the Determination of the Phase Center of Vivaldi-Based UWB Antenna
The phase center of ultra-wide band (UWB) antenna acts a lot to the performance in the time domain . Usually, the width of transmitted impulse is about several hundreds of nanoseconds, so even fine phase center drift will influence the phase of far field much and lead to the waveform dispersion in the time domain [2-3]
if we recognize the far field which is radiated by the antenna as a sphere, then the phase center of antenna should be the center of the sphere. Unluckily, the antenna may have the phase center or not because it correlates to the beam widths and the different tangent planes. In other words, an antenna can’t only have one phase center, the phase center will distribute over the scope under the different beam widths and tangent planes. The shorter the radius of scope, the more stable the phase center is. But the concept above mentioned is only suitable for the conventional antennas, for most of conventional antennas are narrow band, we can deem the phase center constantly in the operating frequency band. For UWB antenna applications, the phase center is required to be stable as the beam width and frequency vary at the same time. Conventionally, the phase center can be deduced according to the directional diagram, but not all of antennas can be implemented because of complicated structures, therefore, numerical methods are effective ways. In this paper, the finite integration method (FIM) is used to calculate the phase center of typical Vivaldi antenna which is used for the ultra-wide band communication system.
KeywordsTangent Plane Beam Width Operating Frequency Band Cross Polarization Level Conventional Antenna
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