Bandwidth- and Gain-Enhanced Vivaldi Antenna Array Fed by Non-uniform T-junction Power Divider for Radio Astronomy Application

A broadband Vivaldi antenna array with good radiation characteristics for radio astronomy applications is presented in this letter. To achieve a good broadband matching, a non-uniform T-junction power divider (NTPD) is adopted to design the multi-port feeding network of antenna array. Thus, the S11 of the proposed NTPD is improved from -5 to -20 dB and its impedance bandwidth is extended from 5.5 GHz to 6 GHz. Meanwhile, the proposed array presents a gain enhancement with 1dB in the low frequency band (1-3 GHz) and 2 dB in the high frequency band (3-6 GHz) with regard to the original array. To verify the design, the proposed Vivaldi antenna array has been fabricated and measured. Its input impedance, return loss, antenna gain and radiation pattern are studied. The realized gain of the Vivaldi antenna array is 5.7-11.3 dB from 1 to 6 GHz. Finally, a reasonable agreement between the measured and simulated results is observed.