Low-Scattering X-Band Planar Phased Vivaldi Array Antenna

A low-scattering X-band planar phased Vivaldi array antenna is proposed in this communication. To reduce the scattering cross section (SCS) of the antenna, two types of Vivaldi elements with the defected ground structures (DGSs) are designed, as well as an embedded absorbing array. Under the normal co-polarized (co-pol) incident waves, the reflections of the two Vivaldi elements are close in magnitude but out of phase. Hence, the scattering of the two elements cancels out in the normal direction. Besides, the problem of obvious bistatic SCS peaks, which always arise when utilizing the phase cancellation method to achieve SCS reduction (SCSR), is solved by the interlacing arrangement of the two elements. Under the cross-polarized (cr-pol) incident waves, the incident power is mostly received and absorbed by the absorbing array, which is composed of the dipole elements in the array center and the slot elements on two edges. According to the measured results, the proposed phased Vivaldi array antenna achieves notable cr-pol SCSR over 6-18 GHz, and the average in-band co-pol SCSR reaches 20 dB simultaneously, without any deterioration on the radiation and scanning performances compared to a referenced one.