An Ultrawideband and Dual-Beam Scanning Array Antenna Charactered by Coding Method

We report an ultrawideband array antenna charactered by coding method. The Vivaldi antenna is chosen as radiating element and the array antenna is fed by a 1 to 8 ultrawideband power divider network. The desired coding states are realized by position reverse of the feeding ports and the power divider network is matched by loading three optimized stepped circuited stubs. A prototype was fabricated and measured and the results show the working bandwidth is approximately 85.7% (from 4 to 10 GHz). More importantly, accurate dual-beam frequency scanning feature is demonstrated and the scanning angle ranges from 21 degrees to 54 degrees (-21 degrees to -54 degrees) when the frequency changes from 4 to 9 GHz. Also, the 3 dB gain bandwidth is ultrawide, from 4 to 10 GHz. The measured results agree well with the simulated ones. Such an ultrawideband array antenna is expected to have potential applications in near future.